https://spudfiles.com/spud_wiki/api.php?action=feedcontributions&feedformat=atom&user=MrCrowleySpudFiles Wiki - User contributions [en]2026-04-18T01:18:17ZUser contributionsMediaWiki 1.44.3https://spudfiles.com/spud_wiki/index.php?title=Piston_valve&diff=4186Piston valve2009-08-20T06:38:56Z<p>MrCrowley: </p>
<hr />
<div>A '''piston valve''' is a [[pilot]] operated [[valve]]. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; [[barrel]] sealing and [[chamber]] sealing.<br />
<br />
<br />
== Barrel sealing valve ==<br />
<br />
In a barrel sealing valve, the piston seals against the breech of the barrel. This is the most common piston valve design.<br />
<br />
=== construction ===<br />
<br />
The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. In the simplest case, equalization is accomplished by allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.<br />
<br />
These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.<br />
<br />
=== Use ===<br />
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.<br />
#The air flows around from the chamber, and into the barrel, propelling the projectile.<br />
<br />
=== Pilot Valves ===<br />
There is a common misconception that a simple blowgun is enough to pilot large piston valves, 1.5" and above. This is not recommended as your cannon will have very bad performance or may not even function at all. For valves 1"-1.25" in diameter, a 1/4" ball valve is recommended. For valves between 1.5" and 2.5" a 1/2" or 3/4" ball valve is probably enough. Anything above that will benefit from a sprinkler valve or a 1" ball valve for a pilot valve. When it comes to pilot valves, bigger is always better.<br />
<br />
== Chamber sealing piston valve ==<br />
<br />
=== construction ===<br />
<br />
The piston of a chamber-sealing piston valve has to seal on both the chamber port and to the pilot volume. This requires that the piston be machined with [[O-ring]]s. A small equalization hole is required; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
The piston is almost always housed in a "t" fitting.<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, chamber sealing sealing" diagram.<br />
<br />
These valves are often used on [[over/under]]s, as the flow is already turned around 90<sup>o</sup>.<br />
<br />
=== Use ===<br />
[[Image:Wcspiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks through the equalization hole in the piston and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the chamber.<br />
#The air flows out of the chamber, and into the barrel, propelling the projectile.<br />
<br />
== Common traits ==<br />
<br />
#The performance of these valves can be calculated with the [[GGDT]].<br />
#If your valve [[honking|honks]], it is probably a good idea to invest in a better pilot valve, though this is more of a problem with barrel-sealing valves.<br />
#In both cases, provided there is a good deal of space around the barrel, the full flow potential of the valve is realized when the piston has moved back 1/4th of the barrel's inside diameter (I.D./4). The derivation of this formula is as follows:<br />
<br />
Given: A = Pi(R)^2<br />
C = 2PiR<br />
T = Piston travel<br />
R = I.D. of barrel / 2<br />
<br />
When the piston moves back, the smallest amount of area exposed is either the area of the circular cross section of the barrel or the area exposed by the piston, which is the side of a cylinder, the bases being the barrel and piston face. The optimal ratio of area exposed between the 2 spots is 1:1, which means the exposed areas should be the same. So one sets the equations A and CT equal, that is A = CT.<br />
<br />
Pi(R)^2 = 2PiR(T)<br />
<br />
Solving for "T" results in:<br />
<br />
R/2 = T which, if one substitutes I.D./2 for R, results in:<br />
<br />
I.D./4 = T<br />
<br />
Many people choose to open larger to provide only one restriction to flow instead of 2 the same size in a row. This is done by allowing the valve to open fully unrestricted and then compress the bumper while opening further. This provides the fastest possible opening time by preventing the piston deceleration while still opening.<br />
<br />
<br />
<br />
#Pneumatic actuation is not mandatory; mechanical means can be used to hold the valve shut, or open it, rather than using the force of the air.<br />
<br />
***The following section submitted by Technician1002***<br />
<br />
The operation of barrel sealing valves falls into 3 categories which is related to the dimensions of the barrel seal or seat to the piston outside diameter.<br />
<br />
=== Large Ratio Piston Valve ===<br />
When the ratio is large in a barrel sealer with either a large piston or small barrel, most of the force to open the valve is controlled by the differential of the chamber pressure and pilot area. As the valve opens, the small area that becomes exposed to the chamber as it opens contributes little to the opening speed. This large area ratio valve are noted for reliable operation as they have the ability to open pistons that don't slide well. Due to the pressure still in the pilot area as they open, as the chamber vents out the barrel, it is often faster than the pilot, so the force used to open the valve vanishes and the pilot pressure unable to keep up with the drop, forces the valve to close. If this repeats as the pilot vents, it is noticeable as honking. This class of valves include pistons with a 2:1 diameter ratio or more. A 2:1 diameter ratio is a 4:1 area ratio. These are not QEV valves because the area sealed by the piston is only 25% of the pilot area so when the valve opens the force change is small. It opens with the pilot at 3/4 the pressure of the chamber. When it opens and the pilot volume is reduced by the piston moving into the pilot space, the rise in pressure in the pilot prevents the piston from opening all the way, so opening speed is directly related to how much faster the pilot can vent over the rate the chamber vents out the barrel. A slow pilot equals a slow valve and may cause honking.<br />
<br />
In a chamber sealer version where the valve seat seals against the chamber, they are fast as the pressure is released and more pressure presses on the larger exposed face of the piston. This style tends to have a fairly large dead space between the valve and projectile. In addition a large piston has a greater mass and as the piston moves, it requires a larger displacement using much of the chamber air energy. If the valve seat is small to use a smaller piston, the small orifice chokes the flow.<br />
<br />
=== Small Ratio or QEV ===<br />
As the ratio of the seat diameter to piston diameter is reduced, the area that the chamber is exposed to is reduced, to the point that the large area of the pilot is able to hold the piston closed until most of the pilot pressure is vented. Even when the pilot area is vented to a low pressure, the initial opening force is low because the area of the piston exposed to the chamber pressure is small as most of the face of the piston is exposed to no pressure in the barrel. This low opening force can cause many headaches with stuck pistons that sometimes fail to fire, and the equalization port may vent enough volume to prevent the pilot area from reaching a low enough pressure to open the valve. The lower the seat to diameter ratio; the lower the initial force the chamber can apply to open the valve, and the faster they snap open when they do get over the initial opening. This faster speed is due to the larger piston face exposed to the chamber pressure when the valve opens and the lower pressure in the pilot area. The lower pressure compresses less and provides less force on the back of the piston when it opens. The closer the ratio is to 1:1 the faster the avalanche, but the initial cracking open of the valve becomes slower as the initial opening force is lower and lower as you approach a 1:1 ratio.<br />
<br />
One attractive feature of this valve is once it unseats and starts to open, the chamber pressure now acting on the face of the piston causes a large spike in opening force as the large barrel facing area is now exposed to the chamber pressure. This type of valve snaps open and is known as a Quick Exhaust Valve or QEV. This style valve is not prone to closing early and honking.<br />
<br />
[[Image:MusketSeat.JPG ]]<br />
<br />
<br />
The barrel sealer QEV piston valve has a large diameter seat in relation to the overall diameter of the piston.<br />
A chamber sealer has a small seat in relation the the overall diameter so the force on the piston grows rapidly as the valve opens.<br />
<br />
Chamber sealer valves have a disadvantage of needing a larger diameter piston for the same size valve seat as a barrel sealer. This adds mass and dead space between the valve piston and projectile. On the positive side, they are more reliable in opening and tend to have most of the opening acceleration early in the opening where it is needed. The drop in acceleration as the valve opens can increase the life expectancy of the valve as they compress the pilot area they slow before impact with the back of the breech.<br />
<br />
=== 1:1 Ratio or QDV ===<br />
A new page dedicated to the QDV is here;<br />
[http://www.spudfiles.com/spud_wiki/index.php/Quick_Dump_Valve Quick Dump Valve Piston]<br />
<br />
If the ratio of the piston diameter is reduced to the diameter of the valve seat in a spool valve, then the valve won't open even when the pilot area is not under pressure. If the chamber is pressurized and no pressure is in the pilot area, the valve has the least back pressure of any of the piston valves and therefore the fastest opening when the valve is unseated by force. Even though the pilot area may half in volume as the piston moves into this space, the pressure rise from 1 atm to 2 atm is still less than the chamber force on the newly exposed face of the piston, so this piston will open fast regardless of the vent size or speed. This last category of piston valve is known as a Quick Dump Valve. To operate this valve in an air cannon, consideration must be made to mechanically move the piston and when the piston moves, the force will avalanche quickly as the piston face becomes exposed to the chamber pressure. For mechanical trigger the use a rope pull or a rod with a "sliding" piston are options to a spring or air start. The loose piston on a rope or rod provides speed as the core can accelerate freely when triggered. Decoupling the triggering mechanism from the piston prevents the trigger from adding to the moving mass of the piston. These valves are not subject to honking, but may "bounce" back closed after the shot by the pressure built up in the pilot area and bumper recoil after the chamber pressure is gone.<br />
<br />
[[Image:QDV_parts.JPG]]<br />
<br />
Assembled 1 inch QDV cannon and damaged can. Projectile was a 1 inch jawbreaker.<br />
[[Image:Marshmallow_cannon.jpg]]<br />
<br />
The quick dump valve has the piston OD the same size as the seat. It requires an external force to start it opening. It has no pilot pressure to hold it against a seat so it is often built with o rings on a piston. The valve cylinder can be built out of a pipe with ports cut in the side.<br />
<br />
A video on the theory of the QDV cannon is here.<br />
[http://www.youtube.com/watch?v=No3nI07mlQo The Quick Dump Valve]<br />
<br />
=== O-Ring Considerations on a Piston Valve ===<br />
To prevent stuck piston valves, consideration must be given to permit a good seal while not stopping movement. <br />
<br />
To prevent stuck or hard to move pistons the o ring should not be compressed flat against the cylinder wall. Since movement is desirable, as well as a seal, we can design the piston to seal without needing to squeeze the o ring. The following video shows the theory fairly well.<br />
<br />
[http://www.youtube.com/watch?v=BbDiZiRVrnk Youtube video on using o rings in air cannons]<br />
<br />
At 4:20 in the video the force needed to move this piston is shown.<br />
<br />
Instead of having O rings in a groove that sit tight against the bottom of the groove and then are compressed by the cylinder, floating rings do not bottom out in the o ring groove. To seal, the pressure trying to blow past the ring seats it against the side of the o ring groove. Air that is able to get under the ring presses outward to apply pressure to the cylinder wall. As the pressure is increased, this force is increased so higher operating pressures make a tighter seal and a little higher friction to movement.<br />
<br />
Floating piston rings fit loose in the grooves. The o ring is sized to be slightly larger than the cylinder diameter it slides inside.<br />
This photo is of a 1 inch quick dump valve piston.<br />
[[Image:Piston_rings.jpg]]<br />
<br />
Here is a drawing showing the force of the pressure on the o ring to provide a tight seal.<br />
[[Image:123_floatingpneumatic1.jpg]]<br />
Source: RL Hudson O-Ring Design & Materials Guide. Used with permission.<br />
<br />
[[category:valves]]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Piston_valve&diff=4185Piston valve2009-08-20T06:36:48Z<p>MrCrowley: </p>
<hr />
<div>A '''piston valve''' is a [[pilot]] operated [[valve]]. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; [[barrel]] sealing and [[chamber]] sealing.<br />
<br />
<br />
== Barrel sealing valve ==<br />
<br />
In a barrel sealing valve, the piston seals against the breech of the barrel. This is the most common piston valve design.<br />
<br />
=== construction ===<br />
<br />
The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. In the simplest case, equalization is accomplished by allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.<br />
<br />
These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.<br />
<br />
=== Use ===<br />
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.<br />
#The air flows around from the chamber, and into the barrel, propelling the projectile.<br />
<br />
=== Pilot Valves ===<br />
There is a common misconception that a simple blowgun is enough to pilot large piston valves, 1.5" and above. This is not recommended as your cannon will have very bad performance or may not even function at all. For valves 1"-1.25" in diameter, a 1/4" ball valve is recommended. For valves between 1.5" and 2.5" a 1/2" or 3/4" ball valve is probably enough. Anything above that will benefit from a sprinkler valve or a 1" ball valve for a pilot valve. When it comes to pilot valves, bigger is always better.<br />
<br />
== Chamber sealing piston valve ==<br />
<br />
=== construction ===<br />
<br />
The piston of a chamber-sealing piston valve has to seal on both the chamber port and to the pilot volume. This requires that the piston be machined with [[O-ring]]s. A small equalization hole is required; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
The piston is almost always housed in a "t" fitting.<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, chamber sealing sealing" diagram.<br />
<br />
These valves are often used on [[over/under]]s, as the flow is already turned around 90<sup>o</sup>.<br />
<br />
=== Use ===<br />
[[Image:Wcspiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks through the equalization hole in the piston and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the chamber.<br />
#The air flows out of the chamber, and into the barrel, propelling the projectile.<br />
<br />
== Common traits ==<br />
<br />
#The performance of these valves can be calculated with the [[GGDT]].<br />
#If your valve [[honking|honks]], it is probably a good idea to invest in a better pilot valve, though this is more of a problem with barrel-sealing valves.<br />
#In both cases, provided there is a good deal of space around the barrel, the full flow potential of the valve is realized when the piston has moved back 1/4th of the barrel's inside diameter (I.D./4). The derivation of this formula is as follows:<br />
<br />
Given: A = Pi(R)^2<br />
C = 2PiR<br />
T = Piston travel<br />
R = I.D. of barrel / 2<br />
<br />
When the piston moves back, the smallest amount of area exposed is either the area of the circular cross section of the barrel or the area exposed by the piston, which is the side of a cylinder, the bases being the barrel and piston face. The optimal ratio of area exposed between the 2 spots is 1:1, which means the exposed areas should be the same. So one sets the equations A and CT equal, that is A = CT.<br />
<br />
Pi(R)^2 = 2PiR(T)<br />
<br />
Solving for "T" results in:<br />
<br />
R/2 = T which, if one substitutes I.D./2 for R, results in:<br />
<br />
I.D./4 = T<br />
<br />
Many people choose to open larger to provide only one restriction to flow instead of 2 the same size in a row. This is done by allowing the valve to open fully unrestricted and then compress the bumper while opening further. This provides the fastest possible opening time by preventing the piston deceleration while still opening.<br />
<br />
<br />
<br />
#Pneumatic actuation is not mandatory; mechanical means can be used to hold the valve shut, or open it, rather than using the force of the air.<br />
<br />
***The following section submitted by Technician1002***<br />
<br />
The operation of barrel sealing valves falls into 3 categories which is related to the dimensions of the barrel seal or seat to the piston outside diameter.<br />
<br />
=== Large Ratio Piston Valve ===<br />
When the ratio is large in a barrel sealer with either a large piston or small barrel, most of the force to open the valve is controlled by the differential of the chamber pressure and pilot area. As the valve opens, the small area that becomes exposed to the chamber as it opens contributes little to the opening speed. This large area ratio valve are noted for reliable operation as they have the ability to open pistons that don't slide well. Due to the pressure still in the pilot area as they open, as the chamber vents out the barrel, it is often faster than the pilot, so the force used to open the valve vanishes and the pilot pressure unable to keep up with the drop, forces the valve to close. If this repeats as the pilot vents, it is noticeable as honking. This class of valves include pistons with a 2:1 diameter ratio or more. A 2:1 diameter ratio is a 4:1 area ratio. These are not QEV valves because the area sealed by the piston is only 25% of the pilot area so when the valve opens the force change is small. It opens with the pilot at 3/4 the pressure of the chamber. When it opens and the pilot volume is reduced by the piston moving into the pilot space, the rise in pressure in the pilot prevents the piston from opening all the way, so opening speed is directly related to how much faster the pilot can vent over the rate the chamber vents out the barrel. A slow pilot equals a slow valve and may cause honking.<br />
<br />
In a chamber sealer version where the valve seat seals against the chamber, they are fast as the pressure is released and more pressure presses on the larger exposed face of the piston. This style tends to have a fairly large dead space between the valve and projectile. In addition a large piston has a greater mass and as the piston moves, it requires a larger displacement using much of the chamber air energy. If the valve seat is small to use a smaller piston, the small orifice chokes the flow.<br />
<br />
=== Small Ratio or QEV ===<br />
As the ratio of the seat diameter to piston diameter is reduced, the area that the chamber is exposed to is reduced, to the point that the large area of the pilot is able to hold the piston closed until most of the pilot pressure is vented. Even when the pilot area is vented to a low pressure, the initial opening force is low because the area of the piston exposed to the chamber pressure is small as most of the face of the piston is exposed to no pressure in the barrel. This low opening force can cause many headaches with stuck pistons that sometimes fail to fire, and the equalization port may vent enough volume to prevent the pilot area from reaching a low enough pressure to open the valve. The lower the seat to diameter ratio; the lower the initial force the chamber can apply to open the valve, and the faster they snap open when they do get over the initial opening. This faster speed is due to the larger piston face exposed to the chamber pressure when the valve opens and the lower pressure in the pilot area. The lower pressure compresses less and provides less force on the back of the piston when it opens. The closer the ratio is to 1:1 the faster the avalanche, but the initial cracking open of the valve becomes slower as the initial opening force is lower and lower as you approach a 1:1 ratio.<br />
<br />
One attractive feature of this valve is once it unseats and starts to open, the chamber pressure now acting on the face of the piston causes a large spike in opening force as the large barrel facing area is now exposed to the chamber pressure. This type of valve snaps open and is known as a Quick Exhaust Valve or QEV. This style valve is not prone to closing early and honking.<br />
<br />
[[Image:MusketSeat.JPG ]]<br />
<br />
<br />
The barrel sealer QEV piston valve has a large diameter seat in relation to the overall diameter of the piston.<br />
A chamber sealer has a small seat in relation the the overall diameter so the force on the piston grows rapidly as the valve opens.<br />
<br />
Chamber sealer valves have a disadvantage of needing a larger diameter piston for the same size valve seat as a barrel sealer. This adds mass and dead space between the valve piston and projectile. On the positive side, they are more reliable in opening and tend to have most of the opening acceleration early in the opening where it is needed. The drop in acceleration as the valve opens can increase the life expectancy of the valve as they compress the pilot area they slow before impact with the back of the breech.<br />
<br />
=== 1:1 Ratio or QDV ===<br />
A new page dedicated to the QDV is here;<br />
[http://www.spudfiles.com/spud_wiki/index.php/Quick_Dump_Valve Quick Dump Valve Piston]<br />
<br />
If the ratio of the piston diameter is reduced to the diameter of the valve seat in a spool valve, then the valve won't open even when the pilot area is not under pressure. If the chamber is pressurized and no pressure is in the pilot area, the valve has the least back pressure of any of the piston valves and therefore the fastest opening when the valve is unseated by force. Even though the pilot area may half in volume as the piston moves into this space, the pressure rise from 1 atm to 2 atm is still less than the chamber force on the newly exposed face of the piston, so this piston will open fast regardless of the vent size or speed. This last category of piston valve is known as a Quick Dump Valve. To operate this valve in an air cannon, consideration must be made to mechanically move the piston and when the piston moves, the force will avalanche quickly as the piston face becomes exposed to the chamber pressure. For mechanical trigger the use a rope pull or a rod with a "sliding" piston are options to a spring or air start. The loose piston on a rope or rod provides speed as the core can accelerate freely when triggered. Decoupling the triggering mechanism from the piston prevents the trigger from adding to the moving mass of the piston. These valves are not subject to honking, but may "bounce" back closed after the shot by the pressure built up in the pilot area and bumper recoil after the chamber pressure is gone.<br />
<br />
[[Image:QDV_parts.JPG]]<br />
<br />
Assembled 1 inch QDV cannon and damaged can. Projectile was a 1 inch jawbreaker.<br />
[[Image:Marshmallow_cannon.jpg]]<br />
<br />
The quick dump valve has the piston OD the same size as the seat. It requires an external force to start it opening. It has no pilot pressure to hold it against a seat so it is often built with o rings on a piston. The valve cylinder can be built out of a pipe with ports cut in the side.<br />
<br />
A video on the theory of the QDV cannon is here.<br />
[http://www.youtube.com/watch?v=No3nI07mlQo The Quick Dump Valve]<br />
<br />
=== O-Ring Considerations on a Piston Valve ===<br />
To prevent stuck piston valves, consideration must be given to permit a good seal while not stopping movement. <br />
<br />
To prevent stuck or hard to move pistons the o ring should not be compressed flat against the cylinder wall. Since movement is desirable, as well as a seal, we can design the piston to seal without needing to squeeze the o ring. The following video shows the theory fairly well.<br />
<br />
[http://www.youtube.com/watch?v=BbDiZiRVrnk Youtube video on using o rings in air cannons]<br />
<br />
At 4:20 in the video the force needed to move this piston is shown.<br />
<br />
Instead of having O rings in a groove that sit tight against the bottom of the groove and then are compressed by the cylinder, floating rings do not bottom out in the o ring groove. To seal, the pressure trying to blow past the ring seats it against the side of the o ring groove. Air that is able to get under the ring presses outward to apply pressure to the cylinder wall. As the pressure is increased, this force is increased so higher operating pressures make a tighter seal and a little higher friction to movement.<br />
<br />
Floating piston rings fit loose in the grooves. The o ring is sized to be slightly larger than the cylinder diameter it slides inside.<br />
<br />
[[Image:Piston_rings.jpg|frame|This photo is of a 1 inch quick dump valve piston.]]<br />
Here is a drawing showing the force of the pressure on the o ring to provide a tight seal.<br />
<br />
[[Image:123_floatingpneumatic1.jpg|frame|Here is a drawing showing the force of the pressure on the o ring to provide a tight seal]]<br />
Source: RL Hudson O-Ring Design & Materials Guide. Used with permission.<br />
<br />
[[category:valves]]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Piston_valve&diff=4184Piston valve2009-08-20T06:36:12Z<p>MrCrowley: </p>
<hr />
<div>A '''piston valve''' is a [[pilot]] operated [[valve]]. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; [[barrel]] sealing and [[chamber]] sealing.<br />
<br />
<br />
== Barrel sealing valve ==<br />
<br />
In a barrel sealing valve, the piston seals against the breech of the barrel. This is the most common piston valve design.<br />
<br />
=== construction ===<br />
<br />
The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. In the simplest case, equalization is accomplished by allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.<br />
<br />
These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.<br />
<br />
=== Use ===<br />
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.<br />
#The air flows around from the chamber, and into the barrel, propelling the projectile.<br />
<br />
=== Pilot Valves ===<br />
There is a common misconception that a simple blowgun is enough to pilot large piston valves, 1.5" and above. This is not recommended as your cannon will have very bad performance or may not even function at all. For valves 1"-1.25" in diameter, a 1/4" ball valve is recommended. For valves between 1.5" and 2.5" a 1/2" or 3/4" ball valve is probably enough. Anything above that will benefit from a sprinkler valve or a 1" ball valve for a pilot valve. When it comes to pilot valves, bigger is always better.<br />
<br />
== Chamber sealing piston valve ==<br />
<br />
=== construction ===<br />
<br />
The piston of a chamber-sealing piston valve has to seal on both the chamber port and to the pilot volume. This requires that the piston be machined with [[O-ring]]s. A small equalization hole is required; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
The piston is almost always housed in a "t" fitting.<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, chamber sealing sealing" diagram.<br />
<br />
These valves are often used on [[over/under]]s, as the flow is already turned around 90<sup>o</sup>.<br />
<br />
=== Use ===<br />
[[Image:Wcspiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks through the equalization hole in the piston and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the chamber.<br />
#The air flows out of the chamber, and into the barrel, propelling the projectile.<br />
<br />
== Common traits ==<br />
<br />
#The performance of these valves can be calculated with the [[GGDT]].<br />
#If your valve [[honking|honks]], it is probably a good idea to invest in a better pilot valve, though this is more of a problem with barrel-sealing valves.<br />
#In both cases, provided there is a good deal of space around the barrel, the full flow potential of the valve is realized when the piston has moved back 1/4th of the barrel's inside diameter (I.D./4). The derivation of this formula is as follows:<br />
<br />
Given: A = Pi(R)^2<br />
C = 2PiR<br />
T = Piston travel<br />
R = I.D. of barrel / 2<br />
<br />
When the piston moves back, the smallest amount of area exposed is either the area of the circular cross section of the barrel or the area exposed by the piston, which is the side of a cylinder, the bases being the barrel and piston face. The optimal ratio of area exposed between the 2 spots is 1:1, which means the exposed areas should be the same. So one sets the equations A and CT equal, that is A = CT.<br />
<br />
Pi(R)^2 = 2PiR(T)<br />
<br />
Solving for "T" results in:<br />
<br />
R/2 = T which, if one substitutes I.D./2 for R, results in:<br />
<br />
I.D./4 = T<br />
<br />
Many people choose to open larger to provide only one restriction to flow instead of 2 the same size in a row. This is done by allowing the valve to open fully unrestricted and then compress the bumper while opening further. This provides the fastest possible opening time by preventing the piston deceleration while still opening.<br />
<br />
<br />
<br />
#Pneumatic actuation is not mandatory; mechanical means can be used to hold the valve shut, or open it, rather than using the force of the air.<br />
<br />
***The following section submitted by Technician1002***<br />
<br />
The operation of barrel sealing valves falls into 3 categories which is related to the dimensions of the barrel seal or seat to the piston outside diameter.<br />
<br />
=== Large Ratio Piston Valve ===<br />
When the ratio is large in a barrel sealer with either a large piston or small barrel, most of the force to open the valve is controlled by the differential of the chamber pressure and pilot area. As the valve opens, the small area that becomes exposed to the chamber as it opens contributes little to the opening speed. This large area ratio valve are noted for reliable operation as they have the ability to open pistons that don't slide well. Due to the pressure still in the pilot area as they open, as the chamber vents out the barrel, it is often faster than the pilot, so the force used to open the valve vanishes and the pilot pressure unable to keep up with the drop, forces the valve to close. If this repeats as the pilot vents, it is noticeable as honking. This class of valves include pistons with a 2:1 diameter ratio or more. A 2:1 diameter ratio is a 4:1 area ratio. These are not QEV valves because the area sealed by the piston is only 25% of the pilot area so when the valve opens the force change is small. It opens with the pilot at 3/4 the pressure of the chamber. When it opens and the pilot volume is reduced by the piston moving into the pilot space, the rise in pressure in the pilot prevents the piston from opening all the way, so opening speed is directly related to how much faster the pilot can vent over the rate the chamber vents out the barrel. A slow pilot equals a slow valve and may cause honking.<br />
<br />
In a chamber sealer version where the valve seat seals against the chamber, they are fast as the pressure is released and more pressure presses on the larger exposed face of the piston. This style tends to have a fairly large dead space between the valve and projectile. In addition a large piston has a greater mass and as the piston moves, it requires a larger displacement using much of the chamber air energy. If the valve seat is small to use a smaller piston, the small orifice chokes the flow.<br />
<br />
=== Small Ratio or QEV ===<br />
As the ratio of the seat diameter to piston diameter is reduced, the area that the chamber is exposed to is reduced, to the point that the large area of the pilot is able to hold the piston closed until most of the pilot pressure is vented. Even when the pilot area is vented to a low pressure, the initial opening force is low because the area of the piston exposed to the chamber pressure is small as most of the face of the piston is exposed to no pressure in the barrel. This low opening force can cause many headaches with stuck pistons that sometimes fail to fire, and the equalization port may vent enough volume to prevent the pilot area from reaching a low enough pressure to open the valve. The lower the seat to diameter ratio; the lower the initial force the chamber can apply to open the valve, and the faster they snap open when they do get over the initial opening. This faster speed is due to the larger piston face exposed to the chamber pressure when the valve opens and the lower pressure in the pilot area. The lower pressure compresses less and provides less force on the back of the piston when it opens. The closer the ratio is to 1:1 the faster the avalanche, but the initial cracking open of the valve becomes slower as the initial opening force is lower and lower as you approach a 1:1 ratio.<br />
<br />
One attractive feature of this valve is once it unseats and starts to open, the chamber pressure now acting on the face of the piston causes a large spike in opening force as the large barrel facing area is now exposed to the chamber pressure. This type of valve snaps open and is known as a Quick Exhaust Valve or QEV. This style valve is not prone to closing early and honking.<br />
<br />
[[Image:MusketSeat.JPG ]]<br />
<br />
<br />
The barrel sealer QEV piston valve has a large diameter seat in relation to the overall diameter of the piston.<br />
A chamber sealer has a small seat in relation the the overall diameter so the force on the piston grows rapidly as the valve opens.<br />
<br />
Chamber sealer valves have a disadvantage of needing a larger diameter piston for the same size valve seat as a barrel sealer. This adds mass and dead space between the valve piston and projectile. On the positive side, they are more reliable in opening and tend to have most of the opening acceleration early in the opening where it is needed. The drop in acceleration as the valve opens can increase the life expectancy of the valve as they compress the pilot area they slow before impact with the back of the breech.<br />
<br />
=== 1:1 Ratio or QDV ===<br />
A new page dedicated to the QDV is here;<br />
[http://www.spudfiles.com/spud_wiki/index.php/Quick_Dump_Valve Quick Dump Valve Piston]<br />
<br />
If the ratio of the piston diameter is reduced to the diameter of the valve seat in a spool valve, then the valve won't open even when the pilot area is not under pressure. If the chamber is pressurized and no pressure is in the pilot area, the valve has the least back pressure of any of the piston valves and therefore the fastest opening when the valve is unseated by force. Even though the pilot area may half in volume as the piston moves into this space, the pressure rise from 1 atm to 2 atm is still less than the chamber force on the newly exposed face of the piston, so this piston will open fast regardless of the vent size or speed. This last category of piston valve is known as a Quick Dump Valve. To operate this valve in an air cannon, consideration must be made to mechanically move the piston and when the piston moves, the force will avalanche quickly as the piston face becomes exposed to the chamber pressure. For mechanical trigger the use a rope pull or a rod with a "sliding" piston are options to a spring or air start. The loose piston on a rope or rod provides speed as the core can accelerate freely when triggered. Decoupling the triggering mechanism from the piston prevents the trigger from adding to the moving mass of the piston. These valves are not subject to honking, but may "bounce" back closed after the shot by the pressure built up in the pilot area and bumper recoil after the chamber pressure is gone.<br />
<br />
[[Image:QDV_parts.JPG]]<br />
<br />
Assembled 1 inch QDV cannon and damaged can. Projectile was a 1 inch jawbreaker.<br />
[[Image:Marshmallow_cannon.jpg]]<br />
<br />
The quick dump valve has the piston OD the same size as the seat. It requires an external force to start it opening. It has no pilot pressure to hold it against a seat so it is often built with o rings on a piston. The valve cylinder can be built out of a pipe with ports cut in the side.<br />
<br />
A video on the theory of the QDV cannon is here.<br />
[http://www.youtube.com/watch?v=No3nI07mlQo The Quick Dump Valve]<br />
<br />
=== O-Ring Considerations on a Piston Valve ===<br />
To prevent stuck piston valves, consideration must be given to permit a good seal while not stopping movement. <br />
<br />
To prevent stuck or hard to move pistons the o ring should not be compressed flat against the cylinder wall. Since movement is desirable, as well as a seal, we can design the piston to seal without needing to squeeze the o ring. The following video shows the theory fairly well.<br />
<br />
[http://www.youtube.com/watch?v=BbDiZiRVrnk Youtube video on using o rings in air cannons]<br />
<br />
At 4:20 in the video the force needed to move this piston is shown.<br />
<br />
Instead of having O rings in a groove that sit tight against the bottom of the groove and then are compressed by the cylinder, floating rings do not bottom out in the o ring groove. To seal, the pressure trying to blow past the ring seats it against the side of the o ring groove. Air that is able to get under the ring presses outward to apply pressure to the cylinder wall. As the pressure is increased, this force is increased so higher operating pressures make a tighter seal and a little higher friction to movement.<br />
<br />
Floating piston rings fit loose in the grooves. The o ring is sized to be slightly larger than the cylinder diameter it slides inside.<br />
<br />
[[Image:Piston_rings.jpg|This photo is of a 1 inch quick dump valve piston.]]<br />
Here is a drawing showing the force of the pressure on the o ring to provide a tight seal.<br />
<br />
[[Image:123_floatingpneumatic1.jpg|frame|Here is a drawing showing the force of the pressure on the o ring to provide a tight seal]]<br />
Source: RL Hudson O-Ring Design & Materials Guide. Used with permission.<br />
<br />
[[category:valves]]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Piston_valve&diff=4183Piston valve2009-08-20T06:34:24Z<p>MrCrowley: </p>
<hr />
<div>A '''piston valve''' is a [[pilot]] operated [[valve]]. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; [[barrel]] sealing and [[chamber]] sealing.<br />
<br />
<br />
== Barrel sealing valve ==<br />
<br />
In a barrel sealing valve, the piston seals against the breech of the barrel. This is the most common piston valve design.<br />
<br />
=== construction ===<br />
<br />
The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. In the simplest case, equalization is accomplished by allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.<br />
<br />
These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.<br />
<br />
=== Use ===<br />
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.<br />
#The air flows around from the chamber, and into the barrel, propelling the projectile.<br />
<br />
=== Pilot Valves ===<br />
There is a common misconception that a simple blowgun is enough to pilot large piston valves, 1.5" and above. This is not recommended as your cannon will have very bad performance or may not even function at all. For valves 1"-1.25" in diameter, a 1/4" ball valve is recommended. For valves between 1.5" and 2.5" a 1/2" or 3/4" ball valve is probably enough. Anything above that will benefit from a sprinkler valve or a 1" ball valve for a pilot valve. When it comes to pilot valves, bigger is always better.<br />
<br />
== Chamber sealing piston valve ==<br />
<br />
=== construction ===<br />
<br />
The piston of a chamber-sealing piston valve has to seal on both the chamber port and to the pilot volume. This requires that the piston be machined with [[O-ring]]s. A small equalization hole is required; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
The piston is almost always housed in a "t" fitting.<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, chamber sealing sealing" diagram.<br />
<br />
These valves are often used on [[over/under]]s, as the flow is already turned around 90<sup>o</sup>.<br />
<br />
=== Use ===<br />
[[Image:Wcspiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks through the equalization hole in the piston and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the chamber.<br />
#The air flows out of the chamber, and into the barrel, propelling the projectile.<br />
<br />
== Common traits ==<br />
<br />
#The performance of these valves can be calculated with the [[GGDT]].<br />
#If your valve [[honking|honks]], it is probably a good idea to invest in a better pilot valve, though this is more of a problem with barrel-sealing valves.<br />
#In both cases, provided there is a good deal of space around the barrel, the full flow potential of the valve is realized when the piston has moved back 1/4th of the barrel's inside diameter (I.D./4). The derivation of this formula is as follows:<br />
<br />
Given: A = Pi(R)^2<br />
C = 2PiR<br />
T = Piston travel<br />
R = I.D. of barrel / 2<br />
<br />
When the piston moves back, the smallest amount of area exposed is either the area of the circular cross section of the barrel or the area exposed by the piston, which is the side of a cylinder, the bases being the barrel and piston face. The optimal ratio of area exposed between the 2 spots is 1:1, which means the exposed areas should be the same. So one sets the equations A and CT equal, that is A = CT.<br />
<br />
Pi(R)^2 = 2PiR(T)<br />
<br />
Solving for "T" results in:<br />
<br />
R/2 = T which, if one substitutes I.D./2 for R, results in:<br />
<br />
I.D./4 = T<br />
<br />
Many people choose to open larger to provide only one restriction to flow instead of 2 the same size in a row. This is done by allowing the valve to open fully unrestricted and then compress the bumper while opening further. This provides the fastest possible opening time by preventing the piston deceleration while still opening.<br />
<br />
<br />
<br />
#Pneumatic actuation is not mandatory; mechanical means can be used to hold the valve shut, or open it, rather than using the force of the air.<br />
<br />
***The following section submitted by Technician1002***<br />
<br />
The operation of barrel sealing valves falls into 3 categories which is related to the dimensions of the barrel seal or seat to the piston outside diameter.<br />
<br />
=== Large Ratio Piston Valve ===<br />
When the ratio is large in a barrel sealer with either a large piston or small barrel, most of the force to open the valve is controlled by the differential of the chamber pressure and pilot area. As the valve opens, the small area that becomes exposed to the chamber as it opens contributes little to the opening speed. This large area ratio valve are noted for reliable operation as they have the ability to open pistons that don't slide well. Due to the pressure still in the pilot area as they open, as the chamber vents out the barrel, it is often faster than the pilot, so the force used to open the valve vanishes and the pilot pressure unable to keep up with the drop, forces the valve to close. If this repeats as the pilot vents, it is noticeable as honking. This class of valves include pistons with a 2:1 diameter ratio or more. A 2:1 diameter ratio is a 4:1 area ratio. These are not QEV valves because the area sealed by the piston is only 25% of the pilot area so when the valve opens the force change is small. It opens with the pilot at 3/4 the pressure of the chamber. When it opens and the pilot volume is reduced by the piston moving into the pilot space, the rise in pressure in the pilot prevents the piston from opening all the way, so opening speed is directly related to how much faster the pilot can vent over the rate the chamber vents out the barrel. A slow pilot equals a slow valve and may cause honking.<br />
<br />
In a chamber sealer version where the valve seat seals against the chamber, they are fast as the pressure is released and more pressure presses on the larger exposed face of the piston. This style tends to have a fairly large dead space between the valve and projectile. In addition a large piston has a greater mass and as the piston moves, it requires a larger displacement using much of the chamber air energy. If the valve seat is small to use a smaller piston, the small orifice chokes the flow.<br />
<br />
=== Small Ratio or QEV ===<br />
As the ratio of the seat diameter to piston diameter is reduced, the area that the chamber is exposed to is reduced, to the point that the large area of the pilot is able to hold the piston closed until most of the pilot pressure is vented. Even when the pilot area is vented to a low pressure, the initial opening force is low because the area of the piston exposed to the chamber pressure is small as most of the face of the piston is exposed to no pressure in the barrel. This low opening force can cause many headaches with stuck pistons that sometimes fail to fire, and the equalization port may vent enough volume to prevent the pilot area from reaching a low enough pressure to open the valve. The lower the seat to diameter ratio; the lower the initial force the chamber can apply to open the valve, and the faster they snap open when they do get over the initial opening. This faster speed is due to the larger piston face exposed to the chamber pressure when the valve opens and the lower pressure in the pilot area. The lower pressure compresses less and provides less force on the back of the piston when it opens. The closer the ratio is to 1:1 the faster the avalanche, but the initial cracking open of the valve becomes slower as the initial opening force is lower and lower as you approach a 1:1 ratio.<br />
<br />
One attractive feature of this valve is once it unseats and starts to open, the chamber pressure now acting on the face of the piston causes a large spike in opening force as the large barrel facing area is now exposed to the chamber pressure. This type of valve snaps open and is known as a Quick Exhaust Valve or QEV. This style valve is not prone to closing early and honking.<br />
<br />
[[Image:MusketSeat.JPG ]]<br />
<br />
<br />
The barrel sealer QEV piston valve has a large diameter seat in relation to the overall diameter of the piston.<br />
A chamber sealer has a small seat in relation the the overall diameter so the force on the piston grows rapidly as the valve opens.<br />
<br />
Chamber sealer valves have a disadvantage of needing a larger diameter piston for the same size valve seat as a barrel sealer. This adds mass and dead space between the valve piston and projectile. On the positive side, they are more reliable in opening and tend to have most of the opening acceleration early in the opening where it is needed. The drop in acceleration as the valve opens can increase the life expectancy of the valve as they compress the pilot area they slow before impact with the back of the breech.<br />
<br />
=== 1:1 Ratio or QDV ===<br />
A new page dedicated to the QDV is here;<br />
[http://www.spudfiles.com/spud_wiki/index.php/Quick_Dump_Valve Quick Dump Valve Piston]<br />
<br />
If the ratio of the piston diameter is reduced to the diameter of the valve seat in a spool valve, then the valve won't open even when the pilot area is not under pressure. If the chamber is pressurized and no pressure is in the pilot area, the valve has the least back pressure of any of the piston valves and therefore the fastest opening when the valve is unseated by force. Even though the pilot area may half in volume as the piston moves into this space, the pressure rise from 1 atm to 2 atm is still less than the chamber force on the newly exposed face of the piston, so this piston will open fast regardless of the vent size or speed. This last category of piston valve is known as a Quick Dump Valve. To operate this valve in an air cannon, consideration must be made to mechanically move the piston and when the piston moves, the force will avalanche quickly as the piston face becomes exposed to the chamber pressure. For mechanical trigger the use a rope pull or a rod with a "sliding" piston are options to a spring or air start. The loose piston on a rope or rod provides speed as the core can accelerate freely when triggered. Decoupling the triggering mechanism from the piston prevents the trigger from adding to the moving mass of the piston. These valves are not subject to honking, but may "bounce" back closed after the shot by the pressure built up in the pilot area and bumper recoil after the chamber pressure is gone.<br />
<br />
[[Image:QDV_parts.JPG]]<br />
<br />
Assembled 1 inch QDV cannon and damaged can. Projectile was a 1 inch jawbreaker.<br />
[[Image:Marshmallow_cannon.jpg]]<br />
<br />
The quick dump valve has the piston OD the same size as the seat. It requires an external force to start it opening. It has no pilot pressure to hold it against a seat so it is often built with o rings on a piston. The valve cylinder can be built out of a pipe with ports cut in the side.<br />
<br />
A video on the theory of the QDV cannon is here.<br />
[http://www.youtube.com/watch?v=No3nI07mlQo The Quick Dump Valve]<br />
<br />
=== O-Ring Considerations on a Piston Valve ===<br />
To prevent stuck piston valves, consideration must be given to permit a good seal while not stopping movement. <br />
<br />
To prevent stuck or hard to move pistons the o ring should not be compressed flat against the cylinder wall. Since movement is desirable, as well as a seal, we can design the piston to seal without needing to squeeze the o ring. The following video shows the theory fairly well.<br />
<br />
[http://www.youtube.com/watch?v=BbDiZiRVrnk Youtube video on using o rings in air cannons]<br />
<br />
At 4:20 in the video the force needed to move this piston is shown.<br />
<br />
Instead of having O rings in a groove that sit tight against the bottom of the groove and then are compressed by the cylinder, floating rings do not bottom out in the o ring groove. To seal, the pressure trying to blow past the ring seats it against the side of the o ring groove. Air that is able to get under the ring presses outward to apply pressure to the cylinder wall. As the pressure is increased, this force is increased so higher operating pressures make a tighter seal and a little higher friction to movement.<br />
<br />
Floating piston rings fit loose in the grooves. The o ring is sized to be slightly larger than the cylinder diameter it slides inside.<br />
This photo is of a 1 inch quick dump valve piston.<br />
<br />
[[Image:Piston_rings.jpg]]<br />
<br />
Here is a drawing showing the force of the pressure on the o ring to provide a tight seal.<br />
<br />
[[Image:123_floatingpneumatic1.jpg]]<br />
[[Image:123_floatingpneumatic1.jpg|frame|Here is a drawing showing the force of the pressure on the o ring to provide a tight seal]]<br />
Source: RL Hudson O-Ring Design & Materials Guide. Used with permission.<br />
<br />
[[category:valves]]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Piston_valve&diff=4182Piston valve2009-08-20T06:19:12Z<p>MrCrowley: </p>
<hr />
<div>A '''piston valve''' is a [[pilot]] operated [[valve]]. It is very similar to a [[diaphragm valve]] in theory, but replaces it's flexible diaphragm with a rigid cylinder. There are 2 varieties; [[barrel]] sealing and [[chamber]] sealing.<br />
<br />
<br />
== Barrel sealing valve ==<br />
<br />
In a barrel sealing valve, the piston seals against the breech of the barrel. This is the most common piston valve design.<br />
<br />
=== construction ===<br />
<br />
The piston is often a well fitting cup-shaped object, such as a end cap. To provide a sealing face, a piece of rubber is attached, typically with a bolt. In the simplest case, equalization is accomplished by allowing the air to leak past the piston and into the chamber. Some people will machine their own pistons, in which case they often build [[O-ring]]s into them. With the O-rings, you need to make a small equalization hole; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, barrel sealing" diagram.<br />
<br />
These valves are often used on [[coaxial]]s and [[over/under]]s. In an over/under, the valve is built in a "T" fitting. The barrel is put co-axially through one end, the pilot and piston are put in the opposite one, and a chamber is connected to the perpendicular opening with a 90° elbow.<br />
<br />
=== Use ===<br />
[[Image:Wpiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks around the piston (or through a small equalization hole) and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the barrel.<br />
#The air flows around from the chamber, and into the barrel, propelling the projectile.<br />
<br />
=== Pilot Valves ===<br />
There is a common misconception that a simple blowgun is enough to pilot large piston valves, 1.5" and above. This is not recommended as your cannon will have very bad performance or may not even function at all. For valves 1"-1.25" in diameter, a 1/4" ball valve is recommended. For valves between 1.5" and 2.5" a 1/2" or 3/4" ball valve is probably enough. Anything above that will benefit from a sprinkler valve or a 1" ball valve for a pilot valve. When it comes to pilot valves, bigger is always better.<br />
<br />
== Chamber sealing piston valve ==<br />
<br />
=== construction ===<br />
<br />
The piston of a chamber-sealing piston valve has to seal on both the chamber port and to the pilot volume. This requires that the piston be machined with [[O-ring]]s. A small equalization hole is required; sometimes this is fancied up to be a homemade [[check valve]].<br />
<br />
The piston is almost always housed in a "t" fitting.<br />
<br />
Because a piston is heavier and harder than a diaphragm, and PVC is somewhat brittle, it is recommended that a bumper of sorts is built into your pilot volume. Common bumpers include heavy-duty rubber hose, and such. This is labeled "'''F'''" in the "use, chamber sealing sealing" diagram.<br />
<br />
These valves are often used on [[over/under]]s, as the flow is already turned around 90<sup>o</sup>.<br />
<br />
=== Use ===<br />
[[Image:Wcspiston.PNG|frame|top=pressurized, bottom=firing]]<br />
Operation:<br />
#Air is added by filling behind the piston (C).<br />
#The piston (E) slides forwards, and seals against the barrel (A). (Alternatively, one can use a spring to move the piston forwards, which allows one to fill [slowly at first, to allow the [[pressure]] to equalize] from the chamber.)<br />
#More air is added, and leaks through the equalization hole in the piston and into the chamber (B), filling it to the desired pressure.<br />
#The [[pilot valve]] (D) behind the piston is opened, the pressure in the pilot volume (C) drops, and the higher pressure in the chamber area pushes the piston away from the chamber.<br />
#The air flows out of the chamber, and into the barrel, propelling the projectile.<br />
<br />
== Common traits ==<br />
<br />
#The performance of these valves can be calculated with the [[GGDT]].<br />
#If your valve [[honking|honks]], it is probably a good idea to invest in a better pilot valve, though this is more of a problem with barrel-sealing valves.<br />
#In both cases, provided there is a good deal of space around the barrel, the full flow potential of the valve is realized when the piston has moved back 1/4th of the barrel's inside diameter (I.D./4). The derivation of this formula is as follows:<br />
<br />
Given: A = Pi(R)^2<br />
C = 2PiR<br />
T = Piston travel<br />
R = I.D. of barrel / 2<br />
<br />
When the piston moves back, the smallest amount of area exposed is either the area of the circular cross section of the barrel or the area exposed by the piston, which is the side of a cylinder, the bases being the barrel and piston face. The optimal ratio of area exposed between the 2 spots is 1:1, which means the exposed areas should be the same. So one sets the equations A and CT equal, that is A = CT.<br />
<br />
Pi(R)^2 = 2PiR(T)<br />
<br />
Solving for "T" results in:<br />
<br />
R/2 = T which, if one substitutes I.D./2 for R, results in:<br />
<br />
I.D./4 = T<br />
<br />
Many people choose to open larger to provide only one restriction to flow instead of 2 the same size in a row. This is done by allowing the valve to open fully unrestricted and then compress the bumper while opening further. This provides the fastest possible opening time by preventing the piston deceleration while still opening.<br />
<br />
<br />
<br />
#Pneumatic actuation is not mandatory; mechanical means can be used to hold the valve shut, or open it, rather than using the force of the air.<br />
<br />
***The following section submitted by Technician1002***<br />
<br />
The operation of barrel sealing valves falls into 3 categories which is related to the dimensions of the barrel seal or seat to the piston outside diameter.<br />
<br />
=== Large Ratio Piston Valve ===<br />
When the ratio is large in a barrel sealer with either a large piston or small barrel, most of the force to open the valve is controlled by the differential of the chamber pressure and pilot area. As the valve opens, the small area that becomes exposed to the chamber as it opens contributes little to the opening speed. This large area ratio valve are noted for reliable operation as they have the ability to open pistons that don't slide well. Due to the pressure still in the pilot area as they open, as the chamber vents out the barrel, it is often faster than the pilot, so the force used to open the valve vanishes and the pilot pressure unable to keep up with the drop, forces the valve to close. If this repeats as the pilot vents, it is noticeable as honking. This class of valves include pistons with a 2:1 diameter ratio or more. A 2:1 diameter ratio is a 4:1 area ratio. These are not QEV valves because the area sealed by the piston is only 25% of the pilot area so when the valve opens the force change is small. It opens with the pilot at 3/4 the pressure of the chamber. When it opens and the pilot volume is reduced by the piston moving into the pilot space, the rise in pressure in the pilot prevents the piston from opening all the way, so opening speed is directly related to how much faster the pilot can vent over the rate the chamber vents out the barrel. A slow pilot equals a slow valve and may cause honking.<br />
<br />
In a chamber sealer version where the valve seat seals against the chamber, they are fast as the pressure is released and more pressure presses on the larger exposed face of the piston. This style tends to have a fairly large dead space between the valve and projectile. In addition a large piston has a greater mass and as the piston moves, it requires a larger displacement using much of the chamber air energy. If the valve seat is small to use a smaller piston, the small orifice chokes the flow.<br />
<br />
=== Small Ratio or QEV ===<br />
As the ratio of the seat diameter to piston diameter is reduced, the area that the chamber is exposed to is reduced, to the point that the large area of the pilot is able to hold the piston closed until most of the pilot pressure is vented. Even when the pilot area is vented to a low pressure, the initial opening force is low because the area of the piston exposed to the chamber pressure is small as most of the face of the piston is exposed to no pressure in the barrel. This low opening force can cause many headaches with stuck pistons that sometimes fail to fire, and the equalization port may vent enough volume to prevent the pilot area from reaching a low enough pressure to open the valve. The lower the seat to diameter ratio; the lower the initial force the chamber can apply to open the valve, and the faster they snap open when they do get over the initial opening. This faster speed is due to the larger piston face exposed to the chamber pressure when the valve opens and the lower pressure in the pilot area. The lower pressure compresses less and provides less force on the back of the piston when it opens. The closer the ratio is to 1:1 the faster the avalanche, but the initial cracking open of the valve becomes slower as the initial opening force is lower and lower as you approach a 1:1 ratio.<br />
<br />
One attractive feature of this valve is once it unseats and starts to open, the chamber pressure now acting on the face of the piston causes a large spike in opening force as the large barrel facing area is now exposed to the chamber pressure. This type of valve snaps open and is known as a Quick Exhaust Valve or QEV. This style valve is not prone to closing early and honking.<br />
<br />
[[Image:MusketSeat.JPG ]]<br />
<br />
<br />
The barrel sealer QEV piston valve has a large diameter seat in relation to the overall diameter of the piston.<br />
A chamber sealer has a small seat in relation the the overall diameter so the force on the piston grows rapidly as the valve opens.<br />
<br />
Chamber sealer valves have a disadvantage of needing a larger diameter piston for the same size valve seat as a barrel sealer. This adds mass and dead space between the valve piston and projectile. On the positive side, they are more reliable in opening and tend to have most of the opening acceleration early in the opening where it is needed. The drop in acceleration as the valve opens can increase the life expectancy of the valve as they compress the pilot area they slow before impact with the back of the breech.<br />
<br />
=== 1:1 Ratio or QDV ===<br />
A new page dedicated to the QDV is here;<br />
[http://www.spudfiles.com/spud_wiki/index.php/Quick_Dump_Valve Quick Dump Valve Piston]<br />
<br />
If the ratio of the piston diameter is reduced to the diameter of the valve seat in a spool valve, then the valve won't open even when the pilot area is not under pressure. If the chamber is pressurized and no pressure is in the pilot area, the valve has the least back pressure of any of the piston valves and therefore the fastest opening when the valve is unseated by force. Even though the pilot area may half in volume as the piston moves into this space, the pressure rise from 1 atm to 2 atm is still less than the chamber force on the newly exposed face of the piston, so this piston will open fast regardless of the vent size or speed. This last category of piston valve is known as a Quick Dump Valve. To operate this valve in an air cannon, consideration must be made to mechanically move the piston and when the piston moves, the force will avalanche quickly as the piston face becomes exposed to the chamber pressure. For mechanical trigger the use a rope pull or a rod with a "sliding" piston are options to a spring or air start. The loose piston on a rope or rod provides speed as the core can accelerate freely when triggered. Decoupling the triggering mechanism from the piston prevents the trigger from adding to the moving mass of the piston. These valves are not subject to honking, but may "bounce" back closed after the shot by the pressure built up in the pilot area and bumper recoil after the chamber pressure is gone.<br />
<br />
[[Image:QDV_parts.JPG]]<br />
<br />
Assembled 1 inch QDV cannon and damaged can. Projectile was a 1 inch jawbreaker.<br />
[[Image:Marshmallow_cannon.jpg]]<br />
<br />
The quick dump valve has the piston OD the same size as the seat. It requires an external force to start it opening. It has no pilot pressure to hold it against a seat so it is often built with o rings on a piston. The valve cylinder can be built out of a pipe with ports cut in the side.<br />
<br />
A video on the theory of the QDV cannon is here.<br />
[http://www.youtube.com/watch?v=No3nI07mlQo The Quick Dump Valve]<br />
<br />
=== O-Ring Considerations on a Piston Valve ===<br />
To prevent stuck piston valves, consideration must be given to permit a good seal while not stopping movement. <br />
<br />
To prevent stuck or hard to move pistons the o ring should not be compressed flat against the cylinder wall. Since movement is desirable, as well as a seal, we can design the piston to seal without needing to squeeze the o ring. The following video shows the theory fairly well.<br />
<br />
[http://www.youtube.com/watch?v=BbDiZiRVrnk Youtube video on using o rings in air cannons]<br />
<br />
At 4:20 in the video the force needed to move this piston is shown.<br />
<br />
Instead of having O rings in a groove that sit tight against the bottom of the groove and then are compressed by the cylinder, floating rings do not bottom out in the o ring groove. To seal, the pressure trying to blow past the ring seats it against the side of the o ring groove. Air that is able to get under the ring presses outward to apply pressure to the cylinder wall. As the pressure is increased, this force is increased so higher operating pressures make a tighter seal and a little higher friction to movement.<br />
<br />
Floating piston rings fit loose in the grooves. The o ring is sized to be slightly larger than the cylinder diameter it slides inside.<br />
This photo is of a 1 inch quick dump valve piston.<br />
<br />
[[Image:Piston_rings.jpg]]<br />
<br />
Here is a drawing showing the force of the pressure on the o ring to provide a tight seal.<br />
<br />
[[Image:123_floatingpneumatic1.jpg]]<br />
<br />
Source: RL Hudson O-Ring Design & Materials Guide. Used with permission.<br />
<br />
[[category:valves]]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Forum_Stickies&diff=4019Forum Stickies2008-12-22T08:00:34Z<p>MrCrowley: </p>
<hr />
<div>==What Is A Sticky?==<br />
A sticky is a topic on a forum that has been edited by a Moderator so that it will always show the 'stickied' topic at the top of the forum section it is posted in.<br />
<br />
Topics are usually stickied for the main reason of them being extremely helpful to all members, new members in particular. The topics usually contain information unique to that topic and are very informative. By making the topic a sticky, it saves members from searching the forum for similar information. As the topic shows at the top of a particular forum section, members will always be able to find it and it will stand out to newer members.<br />
<br />
==Spudfiles Stickies==<br />
Below is a list of the current forum stickies on Spudfiles in there corresponding forum sections.<br />
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===Website Discussion===<br />
*[http://www.spudfiles.com/forums/chatroom-requests-t15608.html Chatroom Requests.] Request members to enter the chatroom for an off-topic or spudgun related talk.<br />
*[http://www.spudfiles.com/forums/posting-images-a-step-by-step-guide-t13190.html Posting images a step-by-step guide.] How to correctly post images in your posts on Spudfiles.<br />
*[http://www.spudfiles.com/forums/spudfiles-extension-for-firefox-t11409.html Spudfiles extension for Firefox.] A useful toolbar for firefox made by a member of Spudfiles.<br />
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===General Spud Cannon Related===<br />
*[http://www.spudfiles.com/forums/my-eye-accident-t15301.html My ~EYE~ Accident.] A topic about a spudgunning accident involving a member of Spudfiles<br />
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*[http://www.spudfiles.com/forums/launcher-failure-analysis-log-t7483.html Launcher Failure Analysis Log.] A topic analysing various spudgun failures.<br />
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<br />
===Pneumatic Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/the-sprinkler-valve-pdf-file-t16786.html The Sprinkler Valve.] A topic of compiled information on the spudder's most common pneumatic valve, the sprinkler valve.<br />
*[http://www.spudfiles.com/forums/piston-valves-explained-visually-t8157.html Piston Valves Explained Visually.] Possibly one of the most well known and informative topic on Spudfiles. This topic shows how piston valves work using animation.<br />
*[http://www.spudfiles.com/forums/sprinkler-valve-troubleshooting-guide-t8780.html Sprinkler Valve Troubleshooting.] Problem with your sprinkler valve? Read this sticky.<br />
*[http://www.spudfiles.com/forums/how-much-co2-do-i-need-t7133.html How much co2 do I need?] This topic has information on how to determine how much CO2 is required for a given chamber size and pressure.<br />
*[http://www.spudfiles.com/forums/read-this-before-posting-t2918.html Read this before posting!.] A warning message from a Moderator on posting.<br />
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*[http://www.spudfiles.com/forums/sparker-reference-guide-t13030.html Sparker Reference Guide.] A helpful topic detailing some of the most common and uncommon ways of generating a spark in a spudgun.<br />
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===Hybrid Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/hybrid-fueling-101-t13602.html Hybrid Fueling 101.] A great topic on how to accurately fuel your hybrid two different ways.<br />
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*[http://www.spudfiles.com/forums/australia-meets-and-club-events-t3394.html Australia - Meets & Club Events.] A thread for Australian members to help organise spudgunning meets in Australia.<br />
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===How-To Database===<br />
*[http://www.spudfiles.com/forums/how-to-make-a-pneumatic-cannon-with-a-2-piston-valve-t10381.html How to make a pneumatic cannon with a 2" piston valve.] A topic with two different how-to's on making 2" piston valves.<br />
*[http://www.spudfiles.com/forums/modding-a-sprinkler-valve-t305.html Modding a sprinkler valve.] How to mod a sprinkler valve tutorial.<br />
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*[http://www.spudfiles.com/forums/valve-cutaways-t273.html Valve Cutaways.] Pictures of different spudgunning valves cut in half.<br />
<br />
<br />
==Important Spudfiles Announcements==<br />
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*[http://www.spudfiles.com/forums/solvent-welding-course-recommended-for-all-t3009.html Solvent Welding Course Recommended For All.] Not sure if you are solvent welding your cannon correctly, or just want a free pen, take this solvent welding course. Highly recommended to insure a safe build.<br />
*[http://www.spudfiles.com/forums/off-topic-and-non-spudgun-related-merged-t8929.html Off-Topic and Non-Spudgun Related Merged.] Outlining why the Off-Topic section was removed/merged.<br />
*[http://www.spudfiles.com/forums/are-you-sure-your-post-belongs-here-t4360.html Are you SURE your post belongs here?] Before making a post in the How-To section, be sure to read this topic first.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Forum_Stickies&diff=4018Forum Stickies2008-12-19T00:18:13Z<p>MrCrowley: /* What is a sticky? */</p>
<hr />
<div>==What Is A Sticky?==<br />
A sticky is a topic on a forum that has been edited by a Moderator so that it will always show the 'stickied' topic at the top of the forum section it is posted in.<br />
<br />
Topics are usually stickied for the main reason of them being extremely helpful to all members, new members in particular. The topics usually contain information unique to that topic and are very informative. By making the topic a sticky, it saves members from searching the forum for similar information. As the topic shows at the top of a particular forum section, members will always be able to find it and it will stand out to newer members.<br />
<br />
==Spudfiles Stickies==<br />
Below is a list of the current forum stickies on Spudfiles in there corresponding forum sections.<br />
<br />
===Website Discussion===<br />
*[http://www.spudfiles.com/forums/chatroom-requests-t15608.html Chatroom Requests.] Request members to enter the chatroom for an off-topic or spudgun related talk.<br />
*[http://www.spudfiles.com/forums/posting-images-a-step-by-step-guide-t13190.html Posting images a step-by-step guide.] How to correctly post images in your posts on Spudfiles.<br />
*[http://www.spudfiles.com/forums/spudfiles-extension-for-firefox-t11409.html Spudfiles extension for Firefox.] A useful toolbar for firefox made by a member of Spudfiles.<br />
*[http://www.spudfiles.com/forums/parroting-t14472.html Parroting.] A topic by a Spudfiles Moderator on forum 'parroting'.<br />
<br />
===General Spud Cannon Related===<br />
*[http://www.spudfiles.com/forums/my-eye-accident-t15301.html My ~EYE~ Accident.] A topic about a spudgunning accident involving a member of Spudfiles<br />
*[http://www.spudfiles.com/forums/newbie-help-t13096.html Newbie Help.] A topic compiling helpful links for new members.<br />
*[http://www.spudfiles.com/forums/launcher-failure-analysis-log-t7483.html Launcher Failure Analysis Log.] A topic analysing various spudgun failures.<br />
*[http://www.spudfiles.com/forums/spudfiles-member-map-t2639.html Spudfiles member map.] A map of some Spudfiles members worldwide.<br />
<br />
===Pneumatic Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/the-sprinkler-valve-pdf-file-t16786.html The Sprinkler Valve.] A topic of compiled information on the spudder's most common pneumatic valve, the sprinkler valve.<br />
*[http://www.spudfiles.com/forums/piston-valves-explained-visually-t8157.html Piston Valves Explained Visually.] Possibly one of the most well known and informative topic on Spudfiles. This topic shows how piston valves work using animation.<br />
*[http://www.spudfiles.com/forums/sprinkler-valve-troubleshooting-guide-t8780.html Sprinkler Valve Troubleshooting.] Problem with your sprinkler valve? Read this sticky.<br />
*[http://www.spudfiles.com/forums/how-much-co2-do-i-need-t7133.html How much co2 do I need?] This topic has information on how to determine how much CO2 is required for a given chamber size and pressure.<br />
*[http://www.spudfiles.com/forums/read-this-before-posting-t2918.html Read this before posting!.] A warning message from a Moderator on posting.<br />
<br />
===Combustion Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/sparker-reference-guide-t13030.html Sparker Reference Guide.] A helpful topic detailing some of the most common and uncommon ways of generating a spark in a spudgun.<br />
*[http://www.spudfiles.com/forums/how-to-build-a-propane-meter-t7234.html How to build a propane meter.] Exactly that.<br />
<br />
===Hybrid Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/hybrid-fueling-101-t13602.html Hybrid Fueling 101.] A great topic on how to accurately fuel your hybrid two different ways.<br />
<br />
===BB/Airsoft/Pellet Gun Discussion===<br />
*[http://www.spudfiles.com/forums/strafer-troubleshooting-guide-t8779.html Strafer Troubleshooting Guide.] Problem with your strafer? Read this sticky.<br />
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===Construction Materials/Ammo Discussion===<br />
*[http://www.spudfiles.com/forums/ammo-ideas-t1724.html Ammo Ideas.] Got an idea for good spudgun ammo? Post it here. Please check first that you are not duplicating anything already previously said in the topic.<br />
*[http://www.spudfiles.com/forums/golf-ball-barrel-faq-t5915.html Golf Ball Barrel FAQ.] All you need to know about golfball barrels being used with spudguns.<br />
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===Non-Spudgun Related Discussion===<br />
*[http://www.spudfiles.com/forums/where-are-you-from-t12433.html Where are you?.] A Spudfiles poll detailing the locations of members who frequent the Spudfiles forum.<br />
*[http://www.spudfiles.com/forums/the-meaning-of-this-section-t14449.html The meaning of this section.] Not quite the meaning of life, but still very important nonetheless.<br />
*[http://www.spudfiles.com/forums/nsgrd-rules-and-guidelines-t11888.html NSGRD Rules and Guidelines.] Rules and guidelines specifically for the Non-Spudgun Related Dsicussion forum.<br />
*[http://www.spudfiles.com/forums/rip-chewy-bill-vogt-memorial-t674.html RIP Chewy (Bill Vogt) -Memorial-.] A thread dedicated to the memory of member and moderator of the old Spudtech forum, Bill Vogt aka Chewy.<br />
<br />
===IPLA Discussion===<br />
*[http://www.spudfiles.com/forums/uk-parts-locations-t3396.html UK - Parts Locations.] A thread to help spudders from the UK with finding spudgun supplies.<br />
*[http://www.spudfiles.com/forums/australia-parts-locations-t3393.html Asutralia - Parts Locations.] Same as above, but for the Aussies.<br />
*[http://www.spudfiles.com/forums/australia-meets-and-club-events-t3394.html Australia - Meets & Club Events.] A thread for Australian members to help organise spudgunning meets in Australia.<br />
*[http://www.spudfiles.com/forums/uk-meets-and-club-events-t3395.html UK - Meets & Club Events.] A thread for UK members to help organise spudgunning meets in the UK.<br />
<br />
===How-To Database===<br />
*[http://www.spudfiles.com/forums/how-to-make-a-pneumatic-cannon-with-a-2-piston-valve-t10381.html How to make a pneumatic cannon with a 2" piston valve.] A topic with two different how-to's on making 2" piston valves.<br />
*[http://www.spudfiles.com/forums/modding-a-sprinkler-valve-t305.html Modding a sprinkler valve.] How to mod a sprinkler valve tutorial.<br />
*[http://www.spudfiles.com/forums/what-would-you-like-to-see-here-t5957.html What would you like to see here?] A thread about possible how-to's members could contribute to the forum.<br />
*[http://www.spudfiles.com/forums/complete-plans-for-advanced-combustion-t4512.html Complete Plans for Advanced Combustion.] Plans on making an advanced combustion spudgun.<br />
<br />
===Theories/Accessories Database===<br />
*[http://www.spudfiles.com/forums/valve-cutaways-t273.html Valve Cutaways.] Pictures of different spudgunning valves cut in half.<br />
<br />
<br />
==Important Spudfiles Announcements==<br />
*[http://www.spudfiles.com/forums/posting-etiquette-t11887.html Posting Etiquette.] All the posting rules for the forum, differs from the actual forum rules.<br />
*[http://www.spudfiles.com/forums/grammar-t1460.html Grammar.] A topic on why proper grammar is important on this forum.<br />
*[http://www.spudfiles.com/forums/attention-comcast-cox-verizon-email-users-t16165.html Attention - Comcast/Cox/Verizon Email Users.] If you use Comcast/Cox/Verison email, read this announcement.<br />
*[http://www.spudfiles.com/forums/caution-odd-advertisements-on-spudfiles-t16756.html Caution - Odd Advertisements On SpudFiles.] Seeing weird advertisements on Spudfiles? You probably have a virus, read this sticky.<br />
*[http://www.spudfiles.com/forums/solvent-welding-course-recommended-for-all-t3009.html Solvent Welding Course Recommended For All.] Not sure if you are solvent welding your cannon correctly, or just want a free pen, take this solvent welding course. Highly recommended to insure a safe build.<br />
*[http://www.spudfiles.com/forums/off-topic-and-non-spudgun-related-merged-t8929.html Off-Topic and Non-Spudgun Related Merged.] Outlining why the Off-Topic section was removed/merged.<br />
*[http://www.spudfiles.com/forums/are-you-sure-your-post-belongs-here-t4360.html Are you SURE your post belongs here?] Before making a post in the How-To section, be sure to read this topic first.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Forum_Stickies&diff=4017Forum Stickies2008-12-19T00:16:35Z<p>MrCrowley: </p>
<hr />
<div>==What is a sticky?==<br />
A sticky is a topic on a forum that has been edited by a Moderator so that it will always show the 'stickied' topic at the top of the forum section it is posted in.<br />
<br />
Topics are usually stickied for the main reason of them being extremely helpful to all members, new members in particular. The topics usually contain information unique to that topic and are very informative. By making the topic a sticky, it saves members from searching the forum for similar information. As the topic shows at the top of a particular forum section, members will always be able to find it and it will stand out to newer members.<br />
<br />
==Spudfiles Stickies==<br />
Below is a list of the current forum stickies on Spudfiles in there corresponding forum sections.<br />
<br />
===Website Discussion===<br />
*[http://www.spudfiles.com/forums/chatroom-requests-t15608.html Chatroom Requests.] Request members to enter the chatroom for an off-topic or spudgun related talk.<br />
*[http://www.spudfiles.com/forums/posting-images-a-step-by-step-guide-t13190.html Posting images a step-by-step guide.] How to correctly post images in your posts on Spudfiles.<br />
*[http://www.spudfiles.com/forums/spudfiles-extension-for-firefox-t11409.html Spudfiles extension for Firefox.] A useful toolbar for firefox made by a member of Spudfiles.<br />
*[http://www.spudfiles.com/forums/parroting-t14472.html Parroting.] A topic by a Spudfiles Moderator on forum 'parroting'.<br />
<br />
===General Spud Cannon Related===<br />
*[http://www.spudfiles.com/forums/my-eye-accident-t15301.html My ~EYE~ Accident.] A topic about a spudgunning accident involving a member of Spudfiles<br />
*[http://www.spudfiles.com/forums/newbie-help-t13096.html Newbie Help.] A topic compiling helpful links for new members.<br />
*[http://www.spudfiles.com/forums/launcher-failure-analysis-log-t7483.html Launcher Failure Analysis Log.] A topic analysing various spudgun failures.<br />
*[http://www.spudfiles.com/forums/spudfiles-member-map-t2639.html Spudfiles member map.] A map of some Spudfiles members worldwide.<br />
<br />
===Pneumatic Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/the-sprinkler-valve-pdf-file-t16786.html The Sprinkler Valve.] A topic of compiled information on the spudder's most common pneumatic valve, the sprinkler valve.<br />
*[http://www.spudfiles.com/forums/piston-valves-explained-visually-t8157.html Piston Valves Explained Visually.] Possibly one of the most well known and informative topic on Spudfiles. This topic shows how piston valves work using animation.<br />
*[http://www.spudfiles.com/forums/sprinkler-valve-troubleshooting-guide-t8780.html Sprinkler Valve Troubleshooting.] Problem with your sprinkler valve? Read this sticky.<br />
*[http://www.spudfiles.com/forums/how-much-co2-do-i-need-t7133.html How much co2 do I need?] This topic has information on how to determine how much CO2 is required for a given chamber size and pressure.<br />
*[http://www.spudfiles.com/forums/read-this-before-posting-t2918.html Read this before posting!.] A warning message from a Moderator on posting.<br />
<br />
===Combustion Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/sparker-reference-guide-t13030.html Sparker Reference Guide.] A helpful topic detailing some of the most common and uncommon ways of generating a spark in a spudgun.<br />
*[http://www.spudfiles.com/forums/how-to-build-a-propane-meter-t7234.html How to build a propane meter.] Exactly that.<br />
<br />
===Hybrid Cannon Discussion===<br />
*[http://www.spudfiles.com/forums/hybrid-fueling-101-t13602.html Hybrid Fueling 101.] A great topic on how to accurately fuel your hybrid two different ways.<br />
<br />
===BB/Airsoft/Pellet Gun Discussion===<br />
*[http://www.spudfiles.com/forums/strafer-troubleshooting-guide-t8779.html Strafer Troubleshooting Guide.] Problem with your strafer? Read this sticky.<br />
<br />
===Construction Materials/Ammo Discussion===<br />
*[http://www.spudfiles.com/forums/ammo-ideas-t1724.html Ammo Ideas.] Got an idea for good spudgun ammo? Post it here. Please check first that you are not duplicating anything already previously said in the topic.<br />
*[http://www.spudfiles.com/forums/golf-ball-barrel-faq-t5915.html Golf Ball Barrel FAQ.] All you need to know about golfball barrels being used with spudguns.<br />
<br />
===Non-Spudgun Related Discussion===<br />
*[http://www.spudfiles.com/forums/where-are-you-from-t12433.html Where are you?.] A Spudfiles poll detailing the locations of members who frequent the Spudfiles forum.<br />
*[http://www.spudfiles.com/forums/the-meaning-of-this-section-t14449.html The meaning of this section.] Not quite the meaning of life, but still very important nonetheless.<br />
*[http://www.spudfiles.com/forums/nsgrd-rules-and-guidelines-t11888.html NSGRD Rules and Guidelines.] Rules and guidelines specifically for the Non-Spudgun Related Dsicussion forum.<br />
*[http://www.spudfiles.com/forums/rip-chewy-bill-vogt-memorial-t674.html RIP Chewy (Bill Vogt) -Memorial-.] A thread dedicated to the memory of member and moderator of the old Spudtech forum, Bill Vogt aka Chewy.<br />
<br />
===IPLA Discussion===<br />
*[http://www.spudfiles.com/forums/uk-parts-locations-t3396.html UK - Parts Locations.] A thread to help spudders from the UK with finding spudgun supplies.<br />
*[http://www.spudfiles.com/forums/australia-parts-locations-t3393.html Asutralia - Parts Locations.] Same as above, but for the Aussies.<br />
*[http://www.spudfiles.com/forums/australia-meets-and-club-events-t3394.html Australia - Meets & Club Events.] A thread for Australian members to help organise spudgunning meets in Australia.<br />
*[http://www.spudfiles.com/forums/uk-meets-and-club-events-t3395.html UK - Meets & Club Events.] A thread for UK members to help organise spudgunning meets in the UK.<br />
<br />
===How-To Database===<br />
*[http://www.spudfiles.com/forums/how-to-make-a-pneumatic-cannon-with-a-2-piston-valve-t10381.html How to make a pneumatic cannon with a 2" piston valve.] A topic with two different how-to's on making 2" piston valves.<br />
*[http://www.spudfiles.com/forums/modding-a-sprinkler-valve-t305.html Modding a sprinkler valve.] How to mod a sprinkler valve tutorial.<br />
*[http://www.spudfiles.com/forums/what-would-you-like-to-see-here-t5957.html What would you like to see here?] A thread about possible how-to's members could contribute to the forum.<br />
*[http://www.spudfiles.com/forums/complete-plans-for-advanced-combustion-t4512.html Complete Plans for Advanced Combustion.] Plans on making an advanced combustion spudgun.<br />
<br />
===Theories/Accessories Database===<br />
*[http://www.spudfiles.com/forums/valve-cutaways-t273.html Valve Cutaways.] Pictures of different spudgunning valves cut in half.<br />
<br />
<br />
==Important Spudfiles Announcements==<br />
*[http://www.spudfiles.com/forums/posting-etiquette-t11887.html Posting Etiquette.] All the posting rules for the forum, differs from the actual forum rules.<br />
*[http://www.spudfiles.com/forums/grammar-t1460.html Grammar.] A topic on why proper grammar is important on this forum.<br />
*[http://www.spudfiles.com/forums/attention-comcast-cox-verizon-email-users-t16165.html Attention - Comcast/Cox/Verizon Email Users.] If you use Comcast/Cox/Verison email, read this announcement.<br />
*[http://www.spudfiles.com/forums/caution-odd-advertisements-on-spudfiles-t16756.html Caution - Odd Advertisements On SpudFiles.] Seeing weird advertisements on Spudfiles? You probably have a virus, read this sticky.<br />
*[http://www.spudfiles.com/forums/solvent-welding-course-recommended-for-all-t3009.html Solvent Welding Course Recommended For All.] Not sure if you are solvent welding your cannon correctly, or just want a free pen, take this solvent welding course. Highly recommended to insure a safe build.<br />
*[http://www.spudfiles.com/forums/off-topic-and-non-spudgun-related-merged-t8929.html Off-Topic and Non-Spudgun Related Merged.] Outlining why the Off-Topic section was removed/merged.<br />
*[http://www.spudfiles.com/forums/are-you-sure-your-post-belongs-here-t4360.html Are you SURE your post belongs here?] Before making a post in the How-To section, be sure to read this topic first.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Main_Page&diff=4015Main Page2008-12-18T06:13:00Z<p>MrCrowley: /* Important & Related Links */</p>
<hr />
<div>== The Spudding Handbook ==<br />
Welcome to The Spudding Handbook! This wiki format handbook contains all of the information you will ever need to build spudguns, and much more besides. The purpose of this handbook is to explain the principles of spudguns and how they are built and operated. All of the information contained in this handbook is free and available to anybody who wishes to view it.<br />
<br />
Look around and enjoy your stay.<br />
--[[User:BC Pneumatics|BC Pneumatics]] 02:13, 31 May 2008 (EDT)<br />
[[Image:Cannon.jpg|frame|An Advanced Combustion Cannon]]<br />
==What is a Spudgun?==<br />
''Main article: [[What_is_a_spudgun%3F|What is a spudgun?]]''<br />
<br />
<br />
There are many different names for spudguns. They are called potato cannons, spud launchers, potato guns, spud cannons, and a host of others. Whatever you decide to call it, all of the aforementioned describe the same type of device: a device used to accelerate a [[potato]] down the [[barrel]], and launch it some distance. While it may offend some purists, the humble little potato is quickly losing favor to other ammunitions such as [[golf ball]]s, [[tennis ball]]s, and other cheap, uniform projectiles.<br />
<br />
==Types of Spudguns==<br />
<br />
<br />
=== [[Pneumatic_launcher|Pneumatic Launchers]] ===<br />
<br />
These use the energy stored in compressed gas to launch a projectile. The launcher's [[chamber]] is [[pressure|pressurized]] and the gas held back from the barrel by a [[valve]]. When the valve is opened the gas is allowed to rapidly expand and escape down the barrel forcing the projectile out before it.<br />
<br />
=== Combustion Launchers ===<br />
<br />
* '''[[Combustion_launcher|Regular Combustions]]'''<br />
<br />
These find the energy needed to launch a projectile from the [[Combustion process|combustion]] of a gaseous [[fuel]] and air mixture. The fuel is added to the air already in the chamber, the chamber is sealed and the mixture ignited. This combustion creates a pressure spike that forces the projectile out through the connected barrel.<br />
<br />
* '''[[Hybrid_launcher|Hybrid Launchers]]'''<br />
<br />
Hybrid launchers are a special type of combustion launcher that use a pre-pressurised fuel/air mixture. This results in a higher pressure and hotter combustion on ignition, thereby transferring more energy to the projectile.<br />
<br />
=== [[BB Machine Gun]]s ===<br />
A [[BB Machine Gun]] (BBMG) is a device designed to shoot a large volume of small diameter ammo, typically plastic airsoft or steel BBs. BBMGs are pneumatic guns but unlike single shot launchers they require a constant gas supply to function.<br />
<br />
==Important & Related Links==<br />
<br />
[[Index|Glossary/Index]]<br />
<br />
[[BCARMS]]<br />
<br />
[[Good technical examples & articles]]<br />
<br />
[[Useful construction links]]<br />
<br />
[[Launcher configuration]]<br />
<br />
[[Computer Applications]]<br />
<br />
[[IPLA|International Potato Launching Association]]<br />
<br />
[[Safety]]<br />
<br />
[[Ammunition]]<br />
<br />
[[Legal issues]]<br />
<br />
[[History]] (A Brief History of Spud Guns)<br />
<br />
[[SpudFiles forum guidelines]]<br />
<br />
[[Spudding Jokes]]<br />
<br />
[[Forum Stickies]] (Some of the most important topics on Spudfiles)<br />
<br />
==External links==<br />
<br />
*[http://en.wikipedia.org/wiki/Spud_gun Wikipedia's page on spudguns]<br />
*[http://www.bavetta.com/aircannon.html Air Cannon Barrel Length Numerical Analysis]<br />
*[http://www.thehalls-in-bfe.com/GGDT Gas Gun Design Tool, simulation program for pneumatic guns]<br />
*[http://www.spudfiles.com/forums/viewtopic.php?p=13324#13324 ATF Correspondence concerning spud gun legality]<br />
*[http://www.spudfiles.com SpudFiles Forum (aka The Spud Cannon Database)]<br />
*[http://www.BCARMS.com BCARMS - Spud Cannon Parts, Accessories, Kits and Launchers]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Forum_Stickies&diff=4014Forum Stickies2008-12-18T06:09:50Z<p>MrCrowley: New page: ==What is a sticky?== A sticky is a topic on a forum that has been edited by a Moderator so that it will always show the 'stickied' topic at the top of the forum section it is posted in. ...</p>
<hr />
<div>==What is a sticky?==<br />
A sticky is a topic on a forum that has been edited by a Moderator so that it will always show the 'stickied' topic at the top of the forum section it is posted in.<br />
<br />
Topics are usually stickied for the main reason of them being extremely helpful to all members, new members in particular. The topics usually contain information unique to that topic and are very informative. By making the topic a sticky, it saves members from searching the forum for similar information. As the topic shows at the top of a particular forum section, members will always be able to find it and it will stand out to newer members.<br />
<br />
Below is a list of the current forum stickies on Spudfiles.<br />
<br />
==Website Discussion==<br />
*[http://www.spudfiles.com/forums/chatroom-requests-t15608.html Chatroom Requests.] Request members to enter the chatroom for an off-topic or spudgun related talk.<br />
*[http://www.spudfiles.com/forums/posting-images-a-step-by-step-guide-t13190.html Posting images a step-by-step guide.] How to correctly post images in your posts on Spudfiles.<br />
*[http://www.spudfiles.com/forums/spudfiles-extension-for-firefox-t11409.html Spudfiles extension for Firefox.] A useful toolbar for firefox made by a member of Spudfiles.<br />
*[http://www.spudfiles.com/forums/parroting-t14472.html Parroting.] A topic by a Spudfiles Moderator on forum 'parroting'.<br />
<br />
==General Spud Cannon Related==<br />
*[http://www.spudfiles.com/forums/my-eye-accident-t15301.html My ~EYE~ Accident.] A topic about a spudgunning accident involving a member of Spudfiles<br />
*[http://www.spudfiles.com/forums/newbie-help-t13096.html Newbie Help.] A topic compiling helpful links for new members.<br />
*[http://www.spudfiles.com/forums/launcher-failure-analysis-log-t7483.html Launcher Failure Analysis Log.] A topic analysing various spudgun failures.<br />
*[http://www.spudfiles.com/forums/spudfiles-member-map-t2639.html Spudfiles member map.] A map of some Spudfiles members worldwide.<br />
<br />
==Pneumatic Cannon Discussion==<br />
*[http://www.spudfiles.com/forums/the-sprinkler-valve-pdf-file-t16786.html The Sprinkler Valve.] A topic of compiled information on the spudder's most common pneumatic valve, the sprinkler valve.<br />
*[http://www.spudfiles.com/forums/piston-valves-explained-visually-t8157.html Piston Valves Explained Visually.] Possibly one of the most well known and informative topic on Spudfiles. This topic shows how piston valves work using animation.<br />
*[http://www.spudfiles.com/forums/sprinkler-valve-troubleshooting-guide-t8780.html Sprinkler Valve Troubleshooting.] Problem with your sprinkler valve? Read this sticky.<br />
*[http://www.spudfiles.com/forums/how-much-co2-do-i-need-t7133.html How much co2 do I need?] This topic has information on how to determine how much CO2 is required for a given chamber size and pressure.<br />
*[http://www.spudfiles.com/forums/read-this-before-posting-t2918.html Read this before posting!.] A warning message from a Moderator on posting.<br />
<br />
==Combustion Cannon Discussion==<br />
*[http://www.spudfiles.com/forums/sparker-reference-guide-t13030.html Sparker Reference Guide.] A helpful topic detailing some of the most common and uncommon ways of generating a spark in a spudgun.<br />
*[http://www.spudfiles.com/forums/how-to-build-a-propane-meter-t7234.html How to build a propane meter.] Exactly that.<br />
<br />
==Hybrid Cannon Discussion==<br />
*[http://www.spudfiles.com/forums/hybrid-fueling-101-t13602.html Hybrid Fueling 101.] A great topic on how to accurately fuel your hybrid two different ways.<br />
<br />
==BB/Airsoft/Pellet Gun Discussion==<br />
*[http://www.spudfiles.com/forums/strafer-troubleshooting-guide-t8779.html Strafer Troubleshooting Guide.] Problem with your strafer? Read this sticky.<br />
<br />
==Construction Materials/Ammo Discussion==<br />
*[http://www.spudfiles.com/forums/ammo-ideas-t1724.html Ammo Ideas.] Got an idea for good spudgun ammo? Post it here. Please check first that you are not duplicating anything already previously said in the topic.<br />
*[http://www.spudfiles.com/forums/golf-ball-barrel-faq-t5915.html Golf Ball Barrel FAQ.] All you need to know about golfball barrels being used with spudguns.<br />
<br />
==Non-Spudgun Related Discussion==<br />
*[http://www.spudfiles.com/forums/where-are-you-from-t12433.html Where are you?.] A Spudfiles poll detailing the locations of members who frequent the Spudfiles forum.<br />
*[http://www.spudfiles.com/forums/the-meaning-of-this-section-t14449.html The meaning of this section.] Not quite the meaning of life, but still very important nonetheless.<br />
*[http://www.spudfiles.com/forums/nsgrd-rules-and-guidelines-t11888.html NSGRD Rules and Guidelines.] Rules and guidelines specifically for the Non-Spudgun Related Dsicussion forum.<br />
*[http://www.spudfiles.com/forums/rip-chewy-bill-vogt-memorial-t674.html RIP Chewy (Bill Vogt) -Memorial-.] A thread dedicated to the memory of member and moderator of the old Spudtech forum, Bill Vogt aka Chewy.<br />
<br />
==IPLA Discussion==<br />
*[http://www.spudfiles.com/forums/uk-parts-locations-t3396.html UK - Parts Locations.] A thread to help spudders from the UK with finding spudgun supplies.<br />
*[http://www.spudfiles.com/forums/australia-parts-locations-t3393.html Asutralia - Parts Locations.] Same as above, but for the Aussies.<br />
*[http://www.spudfiles.com/forums/australia-meets-and-club-events-t3394.html Australia - Meets & Club Events.] A thread for Australian members to help organise spudgunning meets in Australia.<br />
*[http://www.spudfiles.com/forums/uk-meets-and-club-events-t3395.html UK - Meets & Club Events.] A thread for UK members to help organise spudgunning meets in the UK.<br />
<br />
==How-To Database==<br />
*[http://www.spudfiles.com/forums/how-to-make-a-pneumatic-cannon-with-a-2-piston-valve-t10381.html How to make a pneumatic cannon with a 2" piston valve.] A topic with two different how-to's on making 2" piston valves.<br />
*[http://www.spudfiles.com/forums/modding-a-sprinkler-valve-t305.html Modding a sprinkler valve.] How to mod a sprinkler valve tutorial.<br />
*[http://www.spudfiles.com/forums/what-would-you-like-to-see-here-t5957.html What would you like to see here?] A thread about possible how-to's members could contribute to the forum.<br />
*[http://www.spudfiles.com/forums/complete-plans-for-advanced-combustion-t4512.html Complete Plans for Advanced Combustion.] Plans on making an advanced combustion spudgun.<br />
<br />
==Theories/Accessories Database==<br />
*[http://www.spudfiles.com/forums/valve-cutaways-t273.html Valve Cutaways.] Pictures of different spudgunning valves cut in half.<br />
<br />
<br />
==Important Spudfiles Announcements==<br />
*[http://www.spudfiles.com/forums/posting-etiquette-t11887.html Posting Etiquette.] All the posting rules for the forum, differs from the actual forum rules.<br />
*[http://www.spudfiles.com/forums/grammar-t1460.html Grammar.] A topic on why proper grammar is important on this forum.<br />
*[http://www.spudfiles.com/forums/attention-comcast-cox-verizon-email-users-t16165.html Attention - Comcast/Cox/Verizon Email Users.] If you use Comcast/Cox/Verison email, read this announcement.<br />
*[http://www.spudfiles.com/forums/caution-odd-advertisements-on-spudfiles-t16756.html Caution - Odd Advertisements On SpudFiles.] Seeing weird advertisements on Spudfiles? You probably have a virus, read this sticky.<br />
*[http://www.spudfiles.com/forums/solvent-welding-course-recommended-for-all-t3009.html Solvent Welding Course Recommended For All.] Not sure if you are solvent welding your cannon correctly, or just want a free pen, take this solvent welding course. Highly recommended to insure a safe build.<br />
*[http://www.spudfiles.com/forums/off-topic-and-non-spudgun-related-merged-t8929.html Off-Topic and Non-Spudgun Related Merged.] Outlining why the Off-Topic section was removed/merged.<br />
*[http://www.spudfiles.com/forums/are-you-sure-your-post-belongs-here-t4360.html Are you SURE your post belongs here?] Before making a post in the How-To section, be sure to read this topic first.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Good_technical_examples_%26_articles&diff=4009Good technical examples & articles2008-12-16T21:46:38Z<p>MrCrowley: </p>
<hr />
<div>This page is to be filled with the cannons generally considered good technical examples on the forums, or those that people just tend to like.<br />
And the articles that are worth your reading time.<br />
<br />
Obviously this page is under construction, somewhat subjective, and most definitely incomplete, but it's here to help a newbie get themselves well aligned with what spudding actually can be.<br />
<br />
==VERY IMPORTANT RULE==<br />
Most of these topics are fairly old. Please do not post in any topic that you are linked to from this page unless you have a VERY important technical question that is not answered anywhere in the thread.<br />
<br />
Asking for plans in any one of these threads will cause you to become prematurely bald. If you are already bald, you don't want to know what becoming bald again after you are already bald does to you.<br />
<br />
If adding cannons to the list, please put them in the right category, and alphabetically by user. This is to prevent any "This cannon is better, so it should be higher up" edit wars. Also, avoid adding a recent cannon unless it's REALLY special.<br />
Articles have no particular order of preference.<br />
<br />
==Cannons==<br />
<br />
'''Pneumatic'''<br />
*[http://www.spudfiles.com/forums/t-t1342.html Sawn-off riot gun, by Brian the Brain.] A cannon that has inspired a great many people.<br />
*[http://www.spudfiles.com/forums/t-t7862.html S400, by Chaos.] Good looking, well built, and a good performer. 'Nuff said.<br />
*[http://www.spudfiles.com/forums/t-t7899.html GB Semi, by Clide.] Self loading Golf ball gun. Good demonstration of a blowfoward valve. <br />
*[http://www.spudfiles.com/forums/t-t14802.html Portable burst disk cartridges, by Davidvaini.] <br />
*[http://www.spudfiles.com/forums/t-t12103.html SCTBDC, by DYI.] Big-ass pneumatic.<br />
*[http://www.spudfiles.com/forums/t-t6455.html Mini Piston Gun, by ethal1222.] A good lesson in compact building.<br />
*[http://www.spudfiles.com/forums/t-t6013.html Copperhead Prime, by Hotwired.] Good example of a simple, yet functional design that has inspired imitators.<br />
*[http://www.spudfiles.com/forums/t-t10446.html 6mm Burst Disc Pneumatic, by Jackssmirkingrevenge.] Demonstration of the effectiveness of high pressure and a good valve.<br />
*[http://www.spudfiles.com/forums/t-t7694.html RevoSemi, by Keep_it_Real.] A great example of a simple loader. <br />
*[http://www.spudfiles.com/forums/t-t11453.html HEAL, by Ragnarok.] Because I'm a shameless self-promoter.<br />
*[http://www.spudfiles.com/forums/t-t7093.html The SWAT, by schmanman.] Just a very large pneumatic.<br />
*[http://www.spudfiles.com/forums/t-t14348.html The Eclipse, by Solar.] One of the best produced cannons this forum has seen.<br />
*[http://www.spudfiles.com/forums/viewtopic,p,208016.html#208016 4.2 Inch Mortar, by biged.] A very well built replica WW2 mortar.<br />
*[http://www.spudfiles.com/forums/gorts-golf-bag-w-vids-contest-t3458.html Gort's Golf Bag, by sgort87.] A portable pneumatic cannon hidden inside a golf bag.<br />
<br />
'''Combustion'''<br />
*[http://www.spudfiles.com/forums/t-t174.html Revolver X, by Boogieman.] Well known combustion, good demonstration of speeding up shooting.<br />
*[http://www.spudfiles.com/spudtech_archive/viewtopic.php?f=17&t=12971 57.5mm Oxymortar, by Caffeine] <br />
*[http://www.spudfiles.com/forums/t-t15766.html Mk2 Rotary barrelled Combustion, by Critical_Al.] Very well made "Rapid-fire" combustion.<br />
*[http://www.spudfiles.com/forums/t-t4960.html Taternator II, by Dumbascii.] Taking combustion and just throwing overkill at it.<br />
*[http://www.spudfiles.com/forums/t-t14319.html Wood Combustion, by Eddbot.] Not so serious, and not the world's best technical example, but worth a look, because most people like it.<br />
*[http://www.spudfiles.com/forums/t-t7878.html Blue Flame III, by Sgort87.] Again, demonstrations of improving rate of fire.<br />
*[http://www.spudfiles.com/forums/t-t6241.html Collapsible travel combustion, by Sgort87.] Neat concept for a telescoping cannon.<br />
*[http://www.spudfiles.com/forums/t-t1575.html Proton Pack, by Sgort87.] Backpack based chamber, sometimes considered for a cannon design.<br />
*[http://www.spudfiles.com/forums/t-t2736.html 12" Diameter bucket launcher, by Sgort87.] He does a lot of good combustions. Also, adventurous sizewise.<br />
<br />
'''Hybrid'''<br />
*[http://www.spudfiles.com/forums/t-t6822.html HPSCL, by DR.] Often known as the Gen-II tank, an early example (reposted here) of developments in hybrid fuelling.<br />
*[http://www.spudfiles.com/forums/t-t9589.html Piston Hybrid, by Fnord.] A demonstration of an alternate hybrid valve.<br />
*[http://www.spudfiles.com/forums/t-t7857.html FEAR, by Killjoy.] Just a big ass hybrid. Former holder of the spudgun velocity record.<br />
*[http://www.spudfiles.com/forums/t-t15524.html HyGaC20, by Larda.] Current holder of spudgun velocity, and preignition mix pressure records. Also nice to look at.<br />
<br />
'''BBMG/Strafer'''<br />
*[http://www.spudfiles.com/forums/t-t13762.html Deathray, by Brian the Brain.] Simplify, and add pressure.<br />
*[http://www.spudfiles.com/forums/t-t12907.html RC-P240 Vortex cap BBMG, by Imortal87.] A good method of adding magazines to a BBMG.<br />
*[http://www.spudfiles.com/forums/t-t10075.html 6mm Semi by Jackssmirkingrevenge.] Not so much a BBMG, but absolutely great for learning about blow forward loaders.<br />
*[http://www.spudfiles.com/forums/t-t16441.html Ultimate Inline Mk IIIi, by Neospud.] Showing you how a BBMG should be done for practical field use.<br />
<br />
'''Other'''<br />
*[http://www.spudfiles.com/forums/t-t13449.html 28.8kj Electrothermal cannon, by Larda.] Cannon powered by plasma. Somehow even more impressive than it sounds.<br />
<br />
==Articles==<br />
<br />
'''General Forum'''<br />
*[http://www.spudfiles.com/forums/t-t14659.html A ''VERY'' worthwhile read on spudgunning and the forums.] A read of this will get you pretty up to date with the forum's workings.<br />
*[http://www.spudfiles.com/forums/t-t16568.html A spudder's tale.] Not essential reading, but nice anyway.<br />
*[http://www.spudfiles.com/forums/posting-images-a-step-by-step-guide-t13190.html Posting images a step-by-step guide.] How to post images on Spudfiles properly.<br />
*[http://www.spudfiles.com/forums/rules.html Rules.] Main forum rules.<br />
*[http://www.spudfiles.com/forums/viewtopic,p,136508.html#136508 Posting Etiquette.] Posting rules for the Spudfiles forum, differs from the main forum rules.<br />
<br />
'''Forum In-jokes'''<br />
*[http://www.spudfiles.com/forums/t-t13069.html How to deal with frustration.] The famous *facepalmheaddeskcombo* explained.<br />
*[http://www.spudfiles.com/forums/viewtopic,p,133222.html#133222 The Flaming Pink Elephant.] A metaphor for the forum's innuendo, as this is what it is as subtle as.<br />
<br />
'''Safety'''<br />
*[http://www.spudfiles.com/forums/t-t7783.html Things not to do.] A list of accidents people have had, and in many cases, how it could have been avoided.<br />
*[http://www.spudfiles.com/forums/t-t15301.html A tale of shooting yourself in the face.] Again, more accidents.<br />
*[http://www.spudfiles.com/forums/t-t11431.html Predicting if your cannon's recoil is likely to be dangerous.] It is inadvisable for a hand fired cannon to exceed 100 ft-lbs (135 J) of recoil, and even this will be unpleasant.<br />
<br />
'''Construction'''<br />
*[http://www.spudfiles.com/forums/t-t8157.html How piston valves work.] An explanation of what is arguably the best valve in spudding.<br />
*[http://www.spudfiles.com/forums/t-t11866.html High pressure compressors.] How to adapt fridge parts into the spudder's high pressure solution.<br />
*[http://www.spudfiles.com/forums/t-t2546.html A solution to rifling.] How to rifle a PVC barrel.<br />
*[http://www.spudfiles.com/forums/how-to-make-a-pneumatic-cannon-with-a-2-piston-valve-t10381.html How to make a cannon with 2" piston valve.] How to make a 2" piston valve.<br />
*[http://www.spudfiles.com/forums/solvent-welding-course-recommended-for-all-t3009.html Solvent Welding Course.] An online course on how to solvent weld PVC correctly.<br />
<br />
'''Projectiles'''<br />
*[http://www.spudfiles.com/forums/t-t16438.html A fairly interesting thread on projectile shape vs. drag.] It's a bit incoherent at times, but worth the study.<br />
*[http://www.spudfiles.com/forums/t-t13477.html A theory on dart development.]<br />
<br />
'''Aesthetics'''<br />
* [http://www.spudfiles.com/forums/t-t15767.html Making a stock for your launcher?] This will be worth some reading.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Good_technical_examples_%26_articles&diff=4008Good technical examples & articles2008-12-16T21:38:22Z<p>MrCrowley: </p>
<hr />
<div>This page is to be filled with the cannons generally considered good technical examples on the forums, or those that people just tend to like.<br />
And the articles that are worth your reading time.<br />
<br />
Obviously this page is under construction, somewhat subjective, and most definitely incomplete, but it's here to help a newbie get themselves well aligned with what spudding actually can be.<br />
<br />
==VERY IMPORTANT RULE==<br />
Most of these topics are fairly old. Please do not post in any topic that you are linked to from this page unless you have a VERY important technical question that is not answered anywhere in the thread.<br />
<br />
Asking for plans in any one of these threads will cause you to become prematurely bald. If you are already bald, you don't want to know what becoming bald again after you are already bald does to you.<br />
<br />
If adding cannons to the list, please put them in the right category, and alphabetically by user. This is to prevent any "This cannon is better, so it should be higher up" edit wars. Also, avoid adding a recent cannon unless it's REALLY special.<br />
Articles have no particular order of preference.<br />
<br />
==Cannons==<br />
<br />
'''Pneumatic'''<br />
*[http://www.spudfiles.com/forums/t-t1342.html Sawn-off riot gun, by Brian the Brain.] A cannon that has inspired a great many people.<br />
*[http://www.spudfiles.com/forums/t-t7862.html S400, by Chaos.] Good looking, well built, and a good performer. 'Nuff said.<br />
*[http://www.spudfiles.com/forums/t-t7899.html GB Semi, by Clide.] Self loading Golf ball gun. Good demonstration of a blowfoward valve. <br />
*[http://www.spudfiles.com/forums/t-t14802.html Portable burst disk cartridges, by Davidvaini.] <br />
*[http://www.spudfiles.com/forums/t-t12103.html SCTBDC, by DYI.] Big-ass pneumatic.<br />
*[http://www.spudfiles.com/forums/t-t6455.html Mini Piston Gun, by ethal1222.] A good lesson in compact building.<br />
*[http://www.spudfiles.com/forums/t-t6013.html Copperhead Prime, by Hotwired.] Good example of a simple, yet functional design that has inspired imitators.<br />
*[http://www.spudfiles.com/forums/t-t10446.html 6mm Burst Disc Pneumatic, by Jackssmirkingrevenge.] Demonstration of the effectiveness of high pressure and a good valve.<br />
*[http://www.spudfiles.com/forums/t-t7694.html RevoSemi, by Keep_it_Real.] A great example of a simple loader. <br />
*[http://www.spudfiles.com/forums/t-t11453.html HEAL, by Ragnarok.] Because I'm a shameless self-promoter.<br />
*[http://www.spudfiles.com/forums/t-t7093.html The SWAT, by schmanman.] Just a very large pneumatic.<br />
*[http://www.spudfiles.com/forums/t-t14348.html The Eclipse, by Solar.] One of the best produced cannons this forum has seen.<br />
*[http://www.spudfiles.com/forums/viewtopic,p,208016.html#208016 4.2 Inch Mortar, by biged.] A very well built replica WW2 mortar.<br />
*[http://www.spudfiles.com/forums/gorts-golf-bag-w-vids-contest-t3458.html Gort's Golf Bag, by sgort87.] A portable pneumatic cannon hidden inside a golf bag.<br />
<br />
'''Combustion'''<br />
*[http://www.spudfiles.com/forums/t-t174.html Revolver X, by Boogieman.] Well known combustion, good demonstration of speeding up shooting.<br />
*[http://www.spudfiles.com/spudtech_archive/viewtopic.php?f=17&t=12971 57.5mm Oxymortar, by Caffeine] <br />
*[http://www.spudfiles.com/forums/t-t15766.html Mk2 Rotary barrelled Combustion, by Critical_Al.] Very well made "Rapid-fire" combustion.<br />
*[http://www.spudfiles.com/forums/t-t4960.html Taternator II, by Dumbascii.] Taking combustion and just throwing overkill at it.<br />
*[http://www.spudfiles.com/forums/t-t14319.html Wood Combustion, by Eddbot.] Not so serious, and not the world's best technical example, but worth a look, because most people like it.<br />
*[http://www.spudfiles.com/forums/t-t7878.html Blue Flame III, by Sgort87.] Again, demonstrations of improving rate of fire.<br />
*[http://www.spudfiles.com/forums/t-t6241.html Collapsible travel combustion, by Sgort87.] Neat concept for a telescoping cannon.<br />
*[http://www.spudfiles.com/forums/t-t1575.html Proton Pack, by Sgort87.] Backpack based chamber, sometimes considered for a cannon design.<br />
*[http://www.spudfiles.com/forums/t-t2736.html 12" Diameter bucket launcher, by Sgort87.] He does a lot of good combustions. Also, adventurous sizewise.<br />
<br />
'''Hybrid'''<br />
*[http://www.spudfiles.com/forums/t-t6822.html HPSCL, by DR.] Often known as the Gen-II tank, an early example (reposted here) of developments in hybrid fuelling.<br />
*[http://www.spudfiles.com/forums/t-t9589.html Piston Hybrid, by Fnord.] A demonstration of an alternate hybrid valve.<br />
*[http://www.spudfiles.com/forums/t-t7857.html FEAR, by Killjoy.] Just a big ass hybrid. Former holder of the spudgun velocity record.<br />
*[http://www.spudfiles.com/forums/t-t15524.html HyGaC20, by Larda.] Current holder of spudgun velocity, and preignition mix pressure records. Also nice to look at.<br />
<br />
'''BBMG/Strafer'''<br />
*[http://www.spudfiles.com/forums/t-t13762.html Deathray, by Brian the Brain.] Simplify, and add pressure.<br />
*[http://www.spudfiles.com/forums/t-t12907.html RC-P240 Vortex cap BBMG, by Imortal87.] A good method of adding magazines to a BBMG.<br />
*[http://www.spudfiles.com/forums/t-t10075.html 6mm Semi by Jackssmirkingrevenge.] Not so much a BBMG, but absolutely great for learning about blow forward loaders.<br />
*[http://www.spudfiles.com/forums/t-t16441.html Ultimate Inline Mk IIIi, by Neospud.] Showing you how a BBMG should be done for practical field use.<br />
<br />
'''Other'''<br />
*[http://www.spudfiles.com/forums/t-t13449.html 28.8kj Electrothermal cannon, by Larda.] Cannon powered by plasma. Somehow even more impressive than it sounds.<br />
<br />
==Articles==<br />
<br />
'''General Forum'''<br />
*[http://www.spudfiles.com/forums/t-t14659.html A ''VERY'' worthwhile read on spudgunning and the forums.] A read of this will get you pretty up to date with the forum's workings.<br />
*[http://www.spudfiles.com/forums/t-t16568.html A spudder's tale.] Not essential reading, but nice anyway.<br />
<br />
'''Forum In-jokes'''<br />
*[http://www.spudfiles.com/forums/t-t13069.html How to deal with frustration.] The famous *facepalmheaddeskcombo* explained.<br />
*[http://www.spudfiles.com/forums/viewtopic,p,133222.html#133222 The Flaming Pink Elephant.] A metaphor for the forum's innuendo, as this is what it is as subtle as.<br />
<br />
'''Safety'''<br />
*[http://www.spudfiles.com/forums/t-t7783.html Things not to do.] A list of accidents people have had, and in many cases, how it could have been avoided.<br />
*[http://www.spudfiles.com/forums/t-t15301.html A tale of shooting yourself in the face.] Again, more accidents.<br />
*[http://www.spudfiles.com/forums/t-t11431.html Predicting if your cannon's recoil is likely to be dangerous.] It is inadvisable for a hand fired cannon to exceed 100 ft-lbs (135 J) of recoil, and even this will be unpleasant.<br />
<br />
'''Construction'''<br />
*[http://www.spudfiles.com/forums/t-t8157.html How piston valves work.] An explanation of what is arguably the best valve in spudding.<br />
*[http://www.spudfiles.com/forums/t-t11866.html High pressure compressors.] How to adapt fridge parts into the spudder's high pressure solution.<br />
*[http://www.spudfiles.com/forums/t-t2546.html A solution to rifling.] How to rifle a PVC barrel.<br />
<br />
'''Projectiles'''<br />
*[http://www.spudfiles.com/forums/t-t16438.html A fairly interesting thread on projectile shape vs. drag.] It's a bit incoherent at times, but worth the study.<br />
*[http://www.spudfiles.com/forums/t-t13477.html A theory on dart development.]<br />
<br />
'''Aesthetics'''<br />
* [http://www.spudfiles.com/forums/t-t15767.html Making a stock for your launcher?] This will be worth some reading.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Identifying_Pressure_Rated_PVC&diff=3989Identifying Pressure Rated PVC2008-11-18T23:58:52Z<p>MrCrowley: Added specs sheet</p>
<hr />
<div>Pressure Rated PVC is a fairly common type of spudgun material that most spudguns are made from. It can be found at your local Lowes, Home Depot or Ace Hardware in America. If you are outside the US, you are more likely to find cheap PVC at a Plumbing Merchant, but it can also be found in Aus/NZ at a Bunnings or Mitre10.<br />
<br />
Identifying the correct type of PVC to use in a [[Pneumatic]] or [[Hybrid]] cannon is vital because of the high pressures involved.<br />
[[Combustion]] cannons don't need to be made from pressure rated pipe in most cases, but if you don't mind the weight and cost, the additional safety provided by the pipe can only benefit your cannon.<br />
<br />
==PVC and Combustion Cannons==<br />
<br />
Generally, most spudders who build combustion cannons will not use pressure rated PVC due to the relatively low pressure spike generated by most combustion cannons, and the cost and weight of pressure rated PVC. About 30-45 PSI is generated in hairspray fueled cannons and about 60-75 PSI in [[propane]] or [[MAPP]] powered cannons, which DWV (Non-Pressure Rated) PVC or ABS can typically withstand. However, wall thickness should be taken into account if the pipe is not rated.<br />
<br />
There have been few reports of DWV PVC combustion cannons failing, but this is probably due to pipe fatigue, thin-wall PVC usage, or cracks formed from threaded fittings connected to the chamber.<br />
<br />
Advanced Combustion cannons should be constructed with pressure rated pipes.<br />
<br />
==PVC and Pneumatic Cannons==<br />
<br />
Pressure rated components are essential in making a safe [[pneumatic cannon]]. Because of the higher pressures reached by pneumatic cannons compared to combustion cannons, pressure rated fittings are vital. <br />
<br />
Pressure rated PVC is the most common pneumatic cannon material because of the reasonably low cost, availability, and relatively low weight. It also suits a pneumatic very well, having a wide range of different types of fittings and usually a high pressure rating, with a decent safety factor (3, in most cases).<br />
<br />
DWV PVC has been exposed to around 80-120 PSI in a pneumatic, but this is definitely not recommended. DWV has no rating, meaning it could blow as low as 1 PSI.<br />
<br />
==PVC and Hybrid Cannons==<br />
<br />
Pressure rated PVC (Sch 80) was generally a common material in making hybrids until, by general concensus, it was deemed too dangerous after several cannon failures around 4-6x mixes.<br />
<br />
If you plan on making a hybrid from PVC, NSF-PW Sch 80 PVC is the minimum requirement but it would be best to stay under 4x mixes.<br />
<br />
Most hybrids are constructed from galvanized steel pipe, which is more expensive in larger sizes and weighs more, but the pressure rating is far higher.<br />
<br />
==PVC Sch 40 and Sch 80 Specification Table==<br />
[http://www.spudfiles.com/forums/files/pvcspecsheet_196.jpg]<br />
Source: http://www.pvcplus.com/PVC%20schedule_40_&_80_pipe.htm<br />
<br />
==Identifying Pressure Rated PVC By Look==<br />
<br />
If you are having problems separating Pressure Rated PVC components from DWV PVC, these few differences should make it crystal clear next time you go to a hardware store.<br />
<br />
'''DWV Fittings:'''<br />
<br />
DWV PVC fittings have a few obvious traits that you can use to identify them.<br />
[[image:DWV Fittings.jpg|thumb|Non Pressure Rated PVC Fittings (DWV)]]<br />
* Shallow sockets, DWV fittings have shorter socket depths in their fittings.<br />
* Ring around fitting, DWV fittings usually have a 'ring' around the outside of the sockets, Pressure Rated fittings, don't.<br />
* Thickness, DWV fittings and pipe are very thin compared to their Pressure Rated counterparts.<br />
* Odd shape, some DWV fittings look very odd and drastically different to Pressure Rated fittings.<br />
<br />
<br />
<br />
'''Pressure Rated Fittings:'''<br />
<br />
Pressure Rated PVC fittings generally have the opposite traits as DWV fittings.<br />
* Deeper socket lengths<br />
* 'Full' fitting, no rings around the fittings.<br />
* Thickness, thicker then DWV fittings.<br />
* Symmetrical look to the fitting, no odd shapes.<br />
[[Image:PR PVC.jpg|thumb|Pressure Rated PVC Fittings]]<br />
<br />
<br />
<br />
''Common Misconception:'' Even though [http://www.championlighting.com/pics/pumppics/dolphin/bell_red.jpg Bell Reducers] look Pressure rated, in most cases they are not. It is best to stick to [http://www.milmar.com/images/Sch%2040%20Reducing%20Bushing%20(SxS).JPG Reducing Bushings] because they usually are always pressure rated, make sure to check first though.<br />
<br />
==Identifying Pressure Rated PVC By Text==<br />
<br />
''Common Misconception:'' Sch 40 written on the fitting/pipe does not mean the fitting/pipe is pressure rated, the 'Sch' system is a thickness rating, not a pressure rating. You need to look for NSF-PW.<br />
<br />
''Tip:'' On a Pressure Rated fitting, the writing is usually raised and can be read once painted over. In the case of pipe, if enough layers of paint are on the pipe, you probably can't read the print, so make sure to write down what the pipe has written on it before you paint over it.<br />
<br />
''Note:'' The above is intended for identifying American fittings and pipe. To identify Australia/New Zealand fittings, see below.<br />
<br />
<br />
<br />
'''Fittings:'''<br />
<br />
To find out if a fitting is pressure rated, it should have 'NSF-PW' written in raised text, it may also have Sch 40 (or 80,120 etc) on it. Most American fittings don't have a pressure rating on them, but if they have NSF-PW ("PW" stands for Potable Water, which, by nature is under pressure), you're okay, it will be pressure rated.<br />
<br />
'''Pipe:'''<br />
<br />
For pressure rated pipe, it should have written on the side: 'NSF-PW Sch 40 (or 80,120, etc) XXXPSI @73F' <br />
<br />
XXXPSI, is the pressure rating, it changes depending on the 'schedule' rating and the diameter of the pipe. The pipe may also have a different temperature rating, but the most common say '@73F'. <br />
<br />
The pipe may also have 'DWV" written on it, as long as the pipe has a pressure rating, e.g '300PSI @73F' you're okay. <br />
<br />
If it doesn't have 'NSF-PW' or pressure rating, chances are it's DWV.<br />
<br />
<br />
You can also identify Pressure Rated or DWV fittings and pipe by their 'AS' number written on them, but it's not essential to learn. More details about 'AS' numbers coming soon.<br />
<br />
<br />
<br />
'''Identifying Australian/NZ Pressure Rated PVC fittings:'''<br />
<br />
Since Aus/NZ use a different measuring system, PVC fittings and pipe have a different way of identifying if they are Pressure Rated or not.<br />
<br />
<br />
'''Fittings:'''<br />
<br />
To find out if a PVC fitting is Pressure Rated or not, it should have written on it in either raised or plain text, either:<br />
<br />
* Class X (The class ranges from A-F, with F being the most pressure rated, usually Class 'C' is a minimum in a pneumatic.)<br />
* PN XX (The PN (Pressure Number) system has ratings ranging from 0-22+. PN 10, 12 or 18 are the most common and PN 10 should be the lowest rated fitting you should use in a pneumatic.)<br />
<br />
It's that simple. To find the pressure rating in PSI, multiply the PN number by 14.5. E.g PN18 x 14.5PSI = 261PSI.<br />
The PN number is in BAR, to find it in Kpa, multiply the PN number by 100. E.g PN18 x 100 = 1800Kpa.<br />
<br />
'''Pipe:'''<br />
<br />
To find the pressure rating of PVC pipe, use the same system as you did with the fittings. Find the PN or Class number.<br />
Try not to get confused with the 'DN' number, which is the nominal diameter in millimetres. E.g DN50 = Diameter 50mm.<br />
<br />
As with the American system, there is another way to determine the pressure rating, and that is by AS/NZS number. More information to come soon.<br />
<br />
'''European Pressure Rating System:'''<br />
In Europe the EN 1452-2 norm is used to classify pressure rated pipes, and they are identified with a PN (pressure number) code, which stands for the allowable pressure in Bar. The most common ratings are PN10 for pipes and PN16 for fittings, corresponding to 10 Bar (145 Psi) and 16 Bar (230 Psi), but up to PN25 is available.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Identifying_Pressure_Rated_PVC&diff=3575Identifying Pressure Rated PVC2008-03-25T04:10:14Z<p>MrCrowley: </p>
<hr />
<div>Pressure Rated PVC is a fairly common type of spudgun material that most spudguns are made from. It can be found at your local Lowes, Home Depot or Ace Hardware in America. If you are outside the US, you are more likely to find cheap PVC at a Plumbing Merchant, but it can also be found in Aus/NZ at a Bunnings or Mitre10.<br />
<br />
Identifying the correct type of PVC to use in a [[Pneumatic]] or [[Hybrid]] cannon is vital because of the high pressures involved.<br />
[[Combustion]] cannons don't need to be made from pressure rated pipe in most cases, but if you don't mind the weight and cost, the additional safety provided by the pipe can only benefit your cannon.<br />
<br />
==PVC and Combustion Cannons==<br />
<br />
Generally, most spudders who build combustion cannons will not use pressure rated PVC due to the relatively low pressure spike generated by most combustion cannons, and the cost and weight of pressure rated PVC. About 30-45 PSI is generated in hairspray fueled cannons and about 60-75 PSI in [[propane]] or [[MAPP]] powered cannons, which DWV (Non-Pressure Rated) PVC or ABS can typically withstand. However, wall thickness should be taken into account if the pipe is not rated.<br />
<br />
There have been few reports of DWV PVC combustion cannons failing, but this is probably due to pipe fatigue, thin-wall PVC usage, or cracks formed from threaded fittings connected to the chamber.<br />
<br />
Advanced Combustion cannons should be constructed with pressure rated pipes.<br />
<br />
==PVC and Pneumatic Cannons==<br />
<br />
Pressure rated components are essential in making a safe [[pneumatic cannon]]. Because of the higher pressures reached by pneumatic cannons compared to combustion cannons, pressure rated fittings are vital. <br />
<br />
Pressure rated PVC is the most common pneumatic cannon material because of the reasonably low cost, availability, and relatively low weight. It also suits a pneumatic very well, having a wide range of different types of fittings and usually a high pressure rating, with a decent safety factor (3, in most cases).<br />
<br />
DWV PVC has been exposed to around 80-120 PSI in a pneumatic, but this is definitely not recommended. DWV has no rating, meaning it could blow as low as 1 PSI.<br />
<br />
==PVC and Hybrid Cannons==<br />
<br />
Pressure rated PVC (Sch 80) was generally a common material in making hybrids until, by general concensus, it was deemed too dangerous after several cannon failures around 4-6x mixes.<br />
<br />
If you plan on making a hybrid from PVC, NSF-PW Sch 80 PVC is the minimum requirement but it would be best to stay under 4x mixes.<br />
<br />
Most hybrids are constructed from galvanized steel pipe, which is more expensive in larger sizes and weighs more, but the pressure rating is far higher.<br />
<br />
<br />
==Identifying Pressure Rated PVC By Look==<br />
<br />
If you are having problems separating Pressure Rated PVC components from DWV PVC, these few differences should make it crystal clear next time you go to a hardware store.<br />
<br />
'''DWV Fittings:'''<br />
<br />
DWV PVC fittings have a few obvious traits that you can use to identify them.<br />
[[image:DWV Fittings.jpg|thumb|Non Pressure Rated PVC Fittings (DWV)]]<br />
* Shallow sockets, DWV fittings have shorter socket depths in their fittings.<br />
* Ring around fitting, DWV fittings usually have a 'ring' around the outside of the sockets, Pressure Rated fittings, don't.<br />
* Thickness, DWV fittings and pipe are very thin compared to their Pressure Rated counterparts.<br />
* Odd shape, some DWV fittings look very odd and drastically different to Pressure Rated fittings.<br />
<br />
<br />
<br />
'''Pressure Rated Fittings:'''<br />
<br />
Pressure Rated PVC fittings generally have the opposite traits as DWV fittings.<br />
* Deeper socket lengths<br />
* 'Full' fitting, no rings around the fittings.<br />
* Thickness, thicker then DWV fittings.<br />
* Symmetrical look to the fitting, no odd shapes.<br />
[[Image:PR PVC.jpg|thumb|Pressure Rated PVC Fittings]]<br />
<br />
<br />
<br />
''Common Misconception:'' Even though [http://www.championlighting.com/pics/pumppics/dolphin/bell_red.jpg Bell Reducers] look Pressure rated, in most cases they are not. It is best to stick to [http://www.milmar.com/images/Sch%2040%20Reducing%20Bushing%20(SxS).JPG Reducing Bushings] because they usually are always pressure rated, make sure to check first though.<br />
<br />
==Identifying Pressure Rated PVC By Text==<br />
<br />
''Common Misconception:'' Sch 40 written on the fitting/pipe does not mean the fitting/pipe is pressure rated, the 'Sch' system is a thickness rating, not a pressure rating. You need to look for NSF-PW.<br />
<br />
''Tip:'' On a Pressure Rated fitting, the writing is usually raised and can be read once painted over. In the case of pipe, if enough layers of paint are on the pipe, you probably can't read the print, so make sure to write down what the pipe has written on it before you paint over it.<br />
<br />
''Note:'' The above is intended for identifying American fittings and pipe. To identify Australia/New Zealand fittings, see below.<br />
<br />
<br />
<br />
'''Fittings:'''<br />
<br />
To find out if a fitting is pressure rated, it should have 'NSF-PW' written in raised text, it may also have Sch 40 (or 80,120 etc) on it. Most American fittings don't have a pressure rating on them, but if they have NSF-PW ("PW" stands for Potable Water, which, by nature is under pressure), you're okay, it will be pressure rated.<br />
<br />
'''Pipe:'''<br />
<br />
For pressure rated pipe, it should have written on the side: 'NSF-PW Sch 40 (or 80,120, etc) XXXPSI @73F' <br />
<br />
XXXPSI, is the pressure rating, it changes depending on the 'schedule' rating and the diameter of the pipe. The pipe may also have a different temperature rating, but the most common say '@73F'. <br />
<br />
The pipe may also have 'DWV" written on it, as long as the pipe has a pressure rating, e.g '300PSI @73F' you're okay. <br />
<br />
If it doesn't have 'NSF-PW' or pressure rating, chances are it's DWV.<br />
<br />
<br />
You can also identify Pressure Rated or DWV fittings and pipe by their 'AS' number written on them, but it's not essential to learn. More details about 'AS' numbers coming soon.<br />
<br />
<br />
<br />
'''Identifying Australian/NZ Pressure Rated PVC fittings:'''<br />
<br />
Since Aus/NZ use a different measuring system, PVC fittings and pipe have a different way of identifying if they are Pressure Rated or not.<br />
<br />
<br />
'''Fittings:'''<br />
<br />
To find out if a PVC fitting is Pressure Rated or not, it should have written on it in either raised or plain text, either:<br />
<br />
* Class X (The class ranges from A-F, with F being the most pressure rated, usually Class 'C' is a minimum in a pneumatic.)<br />
* PN XX (The PN (Pressure Number) system has ratings ranging from 0-22+. PN 10, 12 or 18 are the most common and PN 10 should be the lowest rated fitting you should use in a pneumatic.)<br />
<br />
It's that simple. To find the pressure rating in PSI, multiply the PN number by 14.5. E.g PN18 x 14.5PSI = 261PSI.<br />
The PN number is in BAR, to find it in Kpa, multiply the PN number by 100. E.g PN18 x 100 = 1800Kpa.<br />
<br />
'''Pipe:'''<br />
<br />
To find the pressure rating of PVC pipe, use the same system as you did with the fittings. Find the PN or Class number.<br />
Try not to get confused with the 'DN' number, which is the nominal diameter in millimetres. E.g DN50 = Diameter 50mm.<br />
<br />
As with the American system, there is another way to determine the pressure rating, and that is by AS/NZS number. More information to come soon.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Identifying_Pressure_Rated_PVC&diff=3519Identifying Pressure Rated PVC2008-02-16T05:26:15Z<p>MrCrowley: New page: Pressure Rated PVC is a fairly common type of spudgun material that most spudguns are made from. It can be found at your local Lowes, Home Depot or Ace Hardware in America. If you are outs...</p>
<hr />
<div>Pressure Rated PVC is a fairly common type of spudgun material that most spudguns are made from. It can be found at your local Lowes, Home Depot or Ace Hardware in America. If you are outside the US, your best bet for cheap PVC is a Plumbing Merchant, but it can also be found in Aus/NZ at a Bunnings or Mitre10.<br />
<br />
Identifying the correct type of PVC to use in a [[Pneumatic]] or [[Hybrid]] cannon is vital because of the high pressures involved.<br />
[[Combustion]] cannons don't need to be made from pressure rated pipe, but if you don't mind the weight and cost, go right ahead.<br />
<br />
==PVC and Combustion Cannons==<br />
<br />
Generally most spudders who build combustion cannons will not use pressure rated PVC due to the combustions low pressure spike and the cost and weight of Pressure Rated PVC. About 30-45PSI is generated in hairspray cannons and about 60-75PSI in [[propane]] or [[MAPP]] powered cannons, which DWV (Non-Pressure Rated) PVC or ABS should be able to take.<br />
<br />
There have been few reports of people having combustuions made from DWV PVC blowing up on them, but this is probably because of pipe fatigue, thin-wall PVC used or cracks formed from threaded fittings in the chamber.<br />
<br />
If you are thinking of making a basic or advanced combustion, DWV ABS is probably the best choice aside from the rarely found, Pressure Rated ABS.<br />
<br />
==PVC and Pneumatics==<br />
<br />
Pressure rated components are essential in making a safe [[pneumatic cannon]]. Because of the higher pressures reached by Pneumatics compared to Combustions, pressure rated fittings are vital. <br />
<br />
Pressure Rated PVC is the most common pneumatic cannon material because of the reasonably low cost, availability and low weight compared to metal fittings. It also suits a pneumatic very well, having a wide range of different types of fittings and usually a high pressure rating.<br />
<br />
People have taken DWV up to around 80-120PSI in a pneumatic, but this is defintely not recommended. DWV has no rating, meaning it could blow as low as 20PSI. Just spend the extra few dollars and get the pressure rated stuff.<br />
<br />
==PVC and Hybrids==<br />
<br />
Pressure rated PVC (Sch 80) was generally a common material in making hybrids until a few people deemed it too dangerous after several cannon failures around 4-6x mixes.<br />
<br />
If you plan on making a hybrid from PVC, NSF-PW Sch 80 PVC is the minimum requirement but it would be best to stay under 4x mixes.<br />
<br />
Now most hybrids are consutrcted from galvanised pipe, which is more expensive in larger sizes and weighs more, but the pressure rating is far higher.<br />
<br />
<br />
==Identifying Pressure Rated PVC By Look==<br />
<br />
If you are having problems seperating Pressure Rated PVC components from DWV PVC, these few differences should make it crystal clear next time you go to a hardware store.<br />
<br />
'''DWV Fittings:'''<br />
<br />
DWV PVC fittings have a few obvious traits that you can use to identify them.<br />
[[image:DWV Fittings.jpg|thumb|Non Pressure Rated PVC Fittings (DWV)]]<br />
* Shallow sockets, DWV fittings have shorter socket depths in their fittings.<br />
* Ring around fitting, DWV fittings usually have a 'ring' around the outside of the sockets, Pressure Rated fittings, don't.<br />
* Thickness, DWV fittings and pipe are very thin compared to their Pressure Rated counterparts.<br />
* Odd shape, some DWV fittings look very odd and drastically different to Pressure Rated fittings.<br />
<br />
<br />
<br />
'''Pressure Rated Fittings:'''<br />
<br />
Pressure Rated PVC fittings generally have the opposite traits as DWV fittings.<br />
* Deeper socket lengths<br />
* 'Full' fitting, no rings around the fittings.<br />
* Thickness, thicker then DWV fittings.<br />
* Symmetrical look to the fitting, no odd shapes.<br />
[[Image:PR PVC.jpg|thumb|Pressure Rated PVC Fittings]]<br />
<br />
<br />
<br />
''Spud Myth:'' Even though [http://www.championlighting.com/pics/pumppics/dolphin/bell_red.jpg Bell Reducers] look Pressure rated, in most cases they are not. It is best to stick to [http://www.milmar.com/images/Sch%2040%20Reducing%20Bushing%20(SxS).JPG Reducing Bushings] because they usually are always pressure rated, make sure to check first though.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Identifying Pressure Rated PVC By Text==<br />
<br />
''Spud Myth:'' Sch 40 written on the fitting/pipe does not mean the fitting/pipe is pressure rated, the 'Sch' system is a thickness rating, not a pressure rating. You need to look for NSF-PW.<br />
<br />
''Tip:'' On a Pressure Rated fitting, the writing is usually raised and can be read once painted over, with pipe, if you have enough layers of paint you probably can't read it, so make sure to write down what the pipe has written on it before you paint over it.<br />
<br />
''Note:'' This is identifying American fittings and pipe. To identify Australia/New Zealand fittings, see below.<br />
<br />
<br />
<br />
'''Fittings:'''<br />
<br />
To find out if a fitting is pressure rated, it should have 'NSF-PW' written in raised text, it may also have Sch 40 (or 80,120 etc) on it. Most American fittings don't have a pressure rating on them, but if they have NSF-PW, you're okay, it will be pressure rated. <br />
<br />
'''Pipe:'''<br />
<br />
For pressure rated pipe, it should have written on the side: 'NSF-PW Sch 40 (or 80,120, etc) XXXPSI @73F' <br />
<br />
XXXPSI, is the pressure rating, it changes depending on the 'schedule' rating and the diameter of the pipe. The pipe may also have a different temperature rating, but the most common say '@73F'. <br />
<br />
The pipe may also have 'DWV" written on it, as long as the pipe has a pressure rating, e.g '300PSI @73F' you're okay. <br />
<br />
If it doesn't have 'NSF-PW' or pressure rating, chances are it's DWV.<br />
<br />
<br />
You can also identify Pressure Rated or DWV fittings and pipe by their 'AS' number written on them, but it's not essential to learn. More details about 'AS' numbers coming soon.<br />
<br />
<br />
<br />
'''Identifying Australian/NZ Pressure Rated PVC fittings:'''<br />
<br />
Since Aus/NZ use a different measuring system, PVC fittings and pipe have a different way of identifying if they are Pressure Rated or not.<br />
<br />
<br />
'''Fittings:'''<br />
<br />
To find out if a PVC fitting is Pressure Rated or not, it should have written on it in either raised or plain text, either:<br />
<br />
* Class X (The class ranges from A-F, with F being the most pressure rated, usually Class 'C' is a minimum in a pneumatic.)<br />
* PN XX (The PN (Pressure Number) system has ratings ranging from 0-22+. PN 10, 12 or 18 are the most common and PN 10 should be the lowest rated fitting you should use in a pneumatic.)<br />
<br />
It's that simple. To find the pressure rating in PSI, multiply the PN number by 14.5. E.g PN18 x 14.5PSI = 261PSI.<br />
The PN number is in BAR, to find it in Kpa, multiply the PN number by 100. E.g PN18 x 100 = 1800Kpa.<br />
<br />
'''Pipe:'''<br />
<br />
To find the pressure rating of PVC pipe, use the same system as you did with the fittings. Find the PN or Class number.<br />
Try not to get confused with the 'DN' number, which is the nominal diameter in millimeters. E.g DN50 = Diameter 50mm.<br />
<br />
As with the American system, there is another way to determine the pressure rating, and that is by AS/NZS number. More information to come soon.</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=File:PR_PVC.jpg&diff=3518File:PR PVC.jpg2008-02-16T04:42:09Z<p>MrCrowley: Pressure Rated PVC Fittings</p>
<hr />
<div>Pressure Rated PVC Fittings</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=File:DWV_Fittings.jpg&diff=3517File:DWV Fittings.jpg2008-02-16T04:37:20Z<p>MrCrowley: DWV Fittings</p>
<hr />
<div>DWV Fittings</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=File:PVC_Elbow.jpg&diff=3516File:PVC Elbow.jpg2008-02-16T04:31:36Z<p>MrCrowley: Pressure Rated PVC Elbow</p>
<hr />
<div>Pressure Rated PVC Elbow</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=Vortex_cap_BBMG&diff=3498Vortex cap BBMG2008-02-15T19:04:24Z<p>MrCrowley: </p>
<hr />
<div>Typically a cap in shape and is made out of strong materials such as PVC or metal. Their construction is similar to the [http://www.spudfiles.com/spud_wiki/index.php?title=Vortex_block Vortex Block], in which an air inlet and a hole for a barrel are drilled perpendicular to each other. The vortex cap was designed by Gatorlangman and provides a small substitute to the standard vortex or inline vortex blocks.<br />
<br />
<br />
Since the cap itself creates the vortex easy modifications can be done to make magazines. A screw on cap with a spring housed inside of a pipe can be snapped down into a vortex cap for an easy-to-use magazine loaded system. Some of the designs for magazines are shown in the image below:<br />
[[Image:vortexcapimage1.jpg]]</div>MrCrowleyhttps://spudfiles.com/spud_wiki/index.php?title=SpudFiles_Wiki:Community_Portal&diff=3092SpudFiles Wiki:Community Portal2007-01-25T06:09:52Z<p>MrCrowley: ABS vs PVC Pros and Cons</p>
<hr />
<div>== '''ABS''' ==<br />
<br />
<br />
'''Pros :'''<br />
<br />
1)Chemical resistance, so can stand up to the average weekender going crazy experimenting with every different thing that can be found in an aerosol can. <br />
<br />
2)Light weight, even the weakest of us has no reason to heft and bear these devices. <br />
<br />
3)Low cost, it can be obtained almost anywhere, in the correct dimensions. <br />
<br />
'''Cons:'''<br />
<br />
1)NOT PRESSURE RATED! This material has been proven to be acceptable, but standard pipe is not certified for any pressure service above those found in gravity drain applications, typically not above 10 psi. The term "cellular core" means that millions of tiny air bubbles were whipped into the plastic before it was run through the extruder. The end result is a very light weight material that in effect is nothing more than a piece of hard foam in the shape of a tube. <br />
<br />
2)If it fails, it will fail. When it goes, it will turn into many little shards of sharp plastic that will invariably find you in some way. <br />
<br />
3)Decomposition products are nasty! If you have ever taken a whiff after firing it a few times, you will get a burning in your nose. This caustic gas is not good for you! <br />
<br />
<br />
== '''PVC''' ==<br />
<br />
<br />
'''Pros:'''<br />
<br />
1)Inexpensive, the pipe is almost free. Fittings are where the money is dropped, but well worth it <br />
<br />
2)Multitude of dimensions to chose from. Pretty much any configuration of pipe fitting can be found somewhere in PVC, but get out your checkbook! 6" sch 80 will run you right around $40 for a 10' piece. <br />
<br />
3)Pressure Rated. What you see is what you get. The rated pressure on the side of the pipe is already conservative, so you don't need to incorporate safety factors, unless you want to. Fittings are always stronger than bulk pipe, as long as the glue joints are made and allowed to cure properly and are Schedule 40. <br />
<br />
'''Cons:'''<br />
<br />
1)Limited Chemical Resistance. Aldehydes and ketones are out, as these readily dissolve the polymer, as in a glue joint, just read the label on the can: Acetone, THF, MEK. Some fuels should be totally avoided such as carb cleaner and insect repellant, don't say I didn't warn you! <br />
<br />
2)More brittle than ABS, but by not using oxygen and just burning fuel and air....should never be a problem. <br />
<br />
3)Cellular core PVC is common at many hardware/home improvement stores. Make sure you buy SCH 40 pipe with a pressure rating printed on the pipe. If the pipe is not specifically marked with a certain PSI rating, IT IS NOT PRESSURE RATED!! <br />
<br />
[[''Source taken from www.spudtech.com'']]<br />
<br />
<br />
THIS IS UNACCEPTABLE!!<br />
http://www.spudfiles.com/spud_wiki/index.php?title=Special:Deadendpages<br />
Look at the number of dead end pages! Not Cool!</div>MrCrowley