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Air pressure multiplier.

Posted: Sun Jun 28, 2009 7:27 pm
by boyntonstu

Posted: Sun Jun 28, 2009 8:37 pm
by Gippeto
I prefer something more like this;

http://www.kissrebreathers.com/Babyboos ... oster.html

Did you have a question??

Posted: Sun Jun 28, 2009 8:43 pm
by boyntonstu
My question has been answered.

Thanks,

BoyntonStu

Posted: Sun Jun 28, 2009 9:01 pm
by mobile chernobyl
They are quite expensive... The KISS model sells as a base model for a scant $1625!!!

These are commonly used for filling paintball tanks as well - allows a regulated SCUBA tank to last much longer and you can use a simple Air compressor with a higher max pressure (around 150PSI) to power the booster, and the SCUBA tank to supply the HP air in at a regulated 500PSI.

Cool concept, in it's simplest form, just think of it as using an air cylinder to push down on a conventional bike pump, and the atmospheric air pressure would be 500PSI.

Posted: Sun Jun 28, 2009 9:10 pm
by boyntonstu
mobile chernobyl wrote:They are quite expensive... The KISS model sells as a base model for a scant $1625!!!

These are commonly used for filling paintball tanks as well - allows a regulated SCUBA tank to last much longer and you can use a simple Air compressor with a higher max pressure (around 150PSI) to power the booster, and the SCUBA tank to supply the HP air in at a regulated 500PSI.

Cool concept, in it's simplest form, just think of it as using an air cylinder to push down on a conventional bike pump, and the atmospheric air pressure would be 500PSI.
A 150 pound crossbow pushing a .25" diameter piston 24" iwould create a a fairly high pressure.

BoyntonStu

Posted: Sun Jun 28, 2009 9:19 pm
by mobile chernobyl
OK....? I thought we were talking about pressure multipliers...

Posted: Sun Jun 28, 2009 9:57 pm
by boyntonstu
mobile chernobyl wrote:OK....? I thought we were talking about pressure multipliers...
"Cool concept, in it's simplest form, just think of it as using an air cylinder to push down on a conventional bike pump, and the atmospheric air pressure would be 500PSI."

I used this example to transition from the air cylinder to the crossbow to push down the small diameter " bicycle pump".

BoyntonStu

Posted: Sun Jun 28, 2009 11:15 pm
by THUNDERLORD
...I used this example to transition from...
I do that quite often, try to add to something and come up with something entirely new but similar.
For example, I was thinking of a "pressure multiplier" which is more of "regenerative" by using a piston inside the pressure chamber, so when the chamber is filled, the existing atmospheric pressure is compressed back into the pressure source. (or spin gears generating elec. or..)
This would also slow the fill rate which is desirable for some designs.
Interesting device/topic. 8)

Posted: Mon Jun 29, 2009 3:47 am
by psycix
I wonder what the efficiency of these things is. They may waste a lot of air...
Actually, this is an air compressor driven by a air motor.

Posted: Mon Jun 29, 2009 4:24 am
by inonickname
I had an idea once to have LP high volume air (120 psi from a shop compressor for example) push against a very large piston, which is connected to a much smaller piston to give a tiny charge or low volume high pressure air for a caliber of under 5mm.

These probably work in a similar way, so yes, they would be extremely inefficient.

Posted: Mon Jun 29, 2009 4:54 am
by Technician1002
Due to the ineffeciencies of high pressure increases in a single stage, very high pressures are often reached with multi stage compressors. Each stage is a smaller volume, but the same power. If for example, a 2 stage compressor is designed to compress 10X each stage, the fisrt stage would compress from 1 Atm to 10 Atm and the second stage at 1/10th the displacement would compress 10 Atm to 100 Atm, a feat very difficult to do in a single stage.

A SCUBA compressor is typicaly a 3 stage compressor.
Image

3 stage SCUBA or Breathing Air compressor. Note the small third cylinder the blue hose connects to. This is designed to deliver 4500 PSI.

http://hotproducts.manufacturer.com/pro ... ckage.html

Posted: Mon Jun 29, 2009 5:22 am
by john bunsenburner
Perhaps one could try to build a multiplier like this, which is very simple and can really be made to get a pressure anywhere from two to ten times as large as the pressure you start of with. All you need is two tubes one with a diameter of lets say two inches and one smaller one with a diameter of half and inch.

Then you feed air into the large tube which has a piston which is connected to a rod which is connected to a piston inside the smaller tube. When the piston reaches a certain distance a hole is reached by the piston and the air can bleed out. At the end of the small tube you have a check valve.

The small tube is also pressurized, like this the piston will slam back before pushing forwards again and cycling like this over and over again. If build correctly this could be made fairly efficient and could prove useful in condjunction to a fridge pump, if you double its pressure and start with 500psi, then that is awsome. You can also just keep cylcing the air through the system multiplying the air pressure every time.

Posted: Mon Jun 29, 2009 5:35 am
by Technician1002
john bunsenburner wrote:Perhaps one could try to build a multiplier like this, which is very simple and can really be made to get a pressure anywhere from two to ten times as large as the pressure you start of with. All you need is two tubes one with a diameter of lets say two inches and one smaller one with a diameter of half and inch.

Then you feed air into the large tube which has a piston which is connected to a rod which is connected to a piston inside the smaller tube. When the piston reaches a certain distance a hole is reached by the piston and the air can bleed out. At the end of the small tube you have a check valve.

The small tube is also pressurized, like this the piston will slam back before pushing forwards again and cycling like this over and over again. If build correctly this could be made fairly efficient and could prove useful in condjunction to a fridge pump, if you double its pressure and start with 500psi, then that is awsome. You can also just keep cylcing the air through the system multiplying the air pressure every time.
Here is a commercial manufactured one.
The model S-86-JN-15 is designed to deliver up to 3100 PSI. Inlet pressure can be as low as 100 PSI with drive pressure from 50psi to 200psi.
It's the bottom item on this page.
Image
http://images.google.com/imgres?imgurl= ... start%3D20

Posted: Mon Jun 29, 2009 6:32 am
by Ragnarok
I'm actually building some of these personally, given I need around about 100 bar for a project, and it's about the only feasible way to go about it.

However, 100 bar parts are not the cheapest or easiest to come by. I've got the tanks to hold that pressure, but the valves needed take some finding and money.

I say some, because in addition to the 100 bar one, I'm also building a mini version which is somewhat similar to what a "Joule Thief" does for batteries, designed to get the last out of a mobile air tank.
I've had to build an automatic regulator for it to really do it efficiently and properly, but it'll let me get 20-25% more shots out of the tank it'll eventually be fitted to, equivalent to being able to still get full feed pressure out of a tank at nearly half that. (However, due to the way the maths works, the tank pressure actually falls to about a quarter of the feed pressure before it gives up.)

It needs a little more work, but it's entertaining enough, in that it suddenly farts when the tank is below the set feed pressure, and the pressure on the downstream side rockets up to the desired result, at least until the tank has dropped down so low that it can no longer put out the juice.

It's dependent on some electronics to keep it all in order, but it's a useful thing to have.

Posted: Mon Jun 29, 2009 10:30 am
by maggotman
thats simlar to what im tryin to make i have a old cast iron compressor with 2 pistons im going to try replace one of the pistons with a smaller one and use it as a second stage