Valve jam with liquid gas

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
User avatar
wyz2285
First Sergeant 2
First Sergeant 2
Austria
Posts: 2381
Joined: Sat Mar 06, 2010 7:50 am
Location: Porto, Portugal
Has thanked: 1 time
Contact:

Fri Aug 28, 2020 4:47 am

So I have been toying around the idea of using propane with solenoid valves and piston valves. However the valve jams every few shoots. The o-rings on the piston are free float and seals fine, but the piston opens very slowly, as if the o-rings are swollen.
Is it because of the cold? Any suggestion regarding the o-ring material?
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
Boomerang
Private
Private
United States of America
Posts: 3
Joined: Thu Aug 20, 2020 4:11 pm
Been thanked: 1 time

Fri Aug 28, 2020 11:51 am

Cooling things down shouldn't make orings expand, but if it gets cold enough, propane/moisture could certainly freeze on the surfaces.

Does it do the same thing if your propane canaster is vertical (top upwards) during the entire fueling process? Idea being to reduce feeding evaporating (and therefore freezing) liquids from the fill mechanics.
User avatar
Moonbogg
Staff Sergeant 2
Staff Sergeant 2
Posts: 1618
Joined: Mon Oct 13, 2008 10:20 pm
Location: SoCal
Has thanked: 59 times
Been thanked: 30 times

Sat Aug 29, 2020 12:41 am

Any chance of some pictures and a description of how it works?
User avatar
Anatine Duo
Specialist
Specialist
Canada
Posts: 147
Joined: Sat Feb 01, 2014 11:16 am
Location: cottage country
Has thanked: 14 times
Been thanked: 3 times

Sat Aug 29, 2020 9:40 am

propane doesn't behave with some rubbers; might be swelling the o-rings

When we switched from acetylene to propane at work we had some torch heads and regulators get fussy
User avatar
wyz2285
First Sergeant 2
First Sergeant 2
Austria
Posts: 2381
Joined: Sat Mar 06, 2010 7:50 am
Location: Porto, Portugal
Has thanked: 1 time
Contact:

Sat Aug 29, 2020 10:24 am

So I started with a coaxial piston launcher with plans to use solenoid to trigger it. However if I fill it with propane in gas form (filling with bottle pointing upwards) it kinda makes a decent Bang. Then I filled it with the propane bottle upside down so the liquid can get in expecting more power, but the Bang was much smaller. I noticed the piston (with o-ring) gets a lot harder to move after use, I kinda have to lube it after every use.
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
User avatar
wyz2285
First Sergeant 2
First Sergeant 2
Austria
Posts: 2381
Joined: Sat Mar 06, 2010 7:50 am
Location: Porto, Portugal
Has thanked: 1 time
Contact:

Sat Aug 29, 2020 10:24 am

So I started with a coaxial piston launcher with plans to use solenoid to trigger it. However if I fill it with propane in gas form (filling with bottle pointing upwards) it kinda makes a decent Bang. Then I filled it with the propane bottle upside down so the liquid can get in expecting more power, but the Bang was much smaller. I noticed the piston (with o-ring) gets a lot harder to move after use, I kinda have to lube it after every use.
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
User avatar
Moonbogg
Staff Sergeant 2
Staff Sergeant 2
Posts: 1618
Joined: Mon Oct 13, 2008 10:20 pm
Location: SoCal
Has thanked: 59 times
Been thanked: 30 times

Mon Aug 31, 2020 6:39 pm

I'd use air personally for a pneumatic. Do the issues arise when using air?
User avatar
wyz2285
First Sergeant 2
First Sergeant 2
Austria
Posts: 2381
Joined: Sat Mar 06, 2010 7:50 am
Location: Porto, Portugal
Has thanked: 1 time
Contact:

Tue Sep 01, 2020 2:34 am

No, with air is fine. However I'm just trying to learn the reason of it, plus I was hoping to use the launcher quite mobile, the portability of a propane can is interesting.
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
User avatar
Brian the brain
Moderator
Moderator
Posts: 3495
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland

Tue Sep 01, 2020 10:56 am

Could it be because you can 't compess a liquid?Too much liquid in the system preventing parts from moving perhaps?
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
User avatar
Moonbogg
Staff Sergeant 2
Staff Sergeant 2
Posts: 1618
Joined: Mon Oct 13, 2008 10:20 pm
Location: SoCal
Has thanked: 59 times
Been thanked: 30 times

Tue Sep 01, 2020 2:07 pm

I'm wondering if temperature could be the culprit. I imagine the propane being cold, and maybe it causes the piston housing to shrink while the piston itself has a different coefficient of thermal expansion, causing it to shrink less than the housing? If there are o-rings, they might stiffen as well due to the cold.
User avatar
wyz2285
First Sergeant 2
First Sergeant 2
Austria
Posts: 2381
Joined: Sat Mar 06, 2010 7:50 am
Location: Porto, Portugal
Has thanked: 1 time
Contact:

Tue Sep 01, 2020 2:22 pm

So I did more testing, the exhaust is too small and gas in liquid form does not flow and pilot the valve properly.
But even if I fill it will gas in gas form, the piston get stiff after not many uses, the o-ring gets really dry. Any suggestion for o-ring material? Or I should used two o-rings so some lube can be trapped in-between?
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
User avatar
Moonbogg
Staff Sergeant 2
Staff Sergeant 2
Posts: 1618
Joined: Mon Oct 13, 2008 10:20 pm
Location: SoCal
Has thanked: 59 times
Been thanked: 30 times

Tue Sep 01, 2020 3:19 pm

Some pictures would help me to think..
User avatar
hectmarr
Corporal 4
Corporal 4
Argentina
Posts: 815
Joined: Sat May 07, 2016 3:49 pm
Location: Argentina
Has thanked: 40 times
Been thanked: 36 times
Contact:

Tue Sep 01, 2020 8:07 pm

Study the possibility of using a lubricant that enters the gas spray, similar to lubrication systems for compressed air, which is used in compressors. On the other hand, the solenoid valves that I have have a maximum and minimum operating temperature, and are for gases, and not for liquids.
Ideas don't make holes. The weapons yes! ;)
User avatar
wyz2285
First Sergeant 2
First Sergeant 2
Austria
Posts: 2381
Joined: Sat Mar 06, 2010 7:50 am
Location: Porto, Portugal
Has thanked: 1 time
Contact:

Wed Sep 02, 2020 3:28 am

I'll get some photos
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
Post Reply