Ways to Compress Air

[ffeoc]

I need to know how I can compress air without an air compressor. Are there any mini compressors or air pumps?
I am working on project at work. I can give much detail, but this item must be able to expel air repeatedly on demand. It can't use an external air source such as (compressed gas bottle). This part should produce about 180 psi to 350 psi of air repeatedly on demand. This item should be no bigger than a fist. Anyone have any idea of where I can start, or websites/books I can get info on producing compress air?

 

[GregLocock]

Go down to your local auto parts store and buy a 12 V tyre inflator. Mine cost me 4 bucks. It will have a life time measure din hours, judging by teh noise and heat!

Good for 250 psi.

Cheers

Greg Locock

 

[ffeoc]

Thats a good idea, but I don't know if I can incorporate that into my project. Thanks I will check that out though.

 

[ffeoc]

I would like to use air pressure theories and laws to create my own air chambers. I would like to use pistons and chambers to compress air to give off short burst of that compressed air.

 

[Sparweb]

You could look around for catalogs (either on the net or in libraries). By knowing what kind of hardware is available, you would save yourself the trouble of re-inventing the wheel.


STF

 

[automatic2]

pistons and chambers, sounds like a classic air compressor. You say psi of 180 - 350, what volumes and duty cycle do you need. What do you have available as power source. Why would a canister not work?. why fist sized?.

 

[Zapster]

Hello,

Depending on the environment that your device needs to operate in, one method stands out in my mind. Heat the air and it will expand. Small air compression devices are commonly used for hand held tools. One that comes to mind is a pneumatic nailer. These devices are readily available for you to inspect if this might be of interest. In essences, the device has a small bottle of propane and a combustion chamber. A small battery operated fan circulates air into the combustion chamber and propane is injected. When ignited the increase in air pressure drives a piston which in turns drive a nail. These are powerful yet small tools. If this might work for you, check them out at your commercial hardware store or lumber yard.

CRG

 

[ffeoc]

Automatic2, I was thinking of something like pistons and chambers. I would like to use only battery power as a source. The size and power of the battery would be determined by the need. A canister would not work, because they would like for it not to have a canister. They would like the product to produce its on compressed air. Something that doesn’t run out of air or something that can recharge it's self by just giving it time. It should the size of a fist or smaller in diameter and a foot or shorter in length. Anything in between would be fine. It would be preferable that the air chamber be length dimension. Thanks

 

[ffeoc]

Zapster, that’s is a good idea. I think I will do that. I'm open to any heat ideas, as long as it is safe and won't explode in someone’s face. With propane it has to be refilled. That’s not what I'm looking for unless the last a long time. Another thing is that this product will project a small delicate projectile. This can only be done with air. A piston can't touch this projectile, only air. Air should be the primary force behind the projectile movement. Thanks; please continue the feedback both of you guys.

 

[ffeoc]

Oh I forgot this will be a hand held device this is when I need those types of dimensions.

 

[IRstuff]

But how much air are you asking for and what is the duty cycle? How long a pulse do you need and how often and how much air?

You can't get good solutions with completely specifying the problem.

TTFN

 

[Scipio]

Handheld, diameter of a fist and a foot long or shorter, must be air, delicate projectile - sounds like you're trying to build a paintball gun with a built-in air compressor

Don't know how much luck you'll have with a battery, I would think any battery capable of delivering enough juice for the volume & pressure of air you need the battery will either need constant changing or be the size of a car battery. One point nobody else seems to be concerned with though, do you have any temperature constraints? Even going from 10 psig to 180 psig with an industrial reciprocating compression would probably require a three stage machine with interstage cooling. That's a 13.9:1 compression ratio, adiabatic compression would produce a discharge temperature in the neighborhood of 550-600°F.

 

[ffeoc]

Scipio,

How did you come up with the concept of a 13.9:1 compression ratio?

 

[Scipio]

ffeoc,

Well, I'm assuming you're drawing atmospheric air into your suction and compressing it to a minimum of 180 psig. Using 14 psia for an atmospheric pressure just for the sake of an example you are compressing from 14 psia up to 194 psia. 194/14 = 13.9. Or did I read it wrong and you're actually boosting from 180 psig suction and discharging at 350 psig?

 

[griffengm]

Could you use a solenoid to power the piston? Should keep the mechanism simple if you can get sufficient stroke and power.
Can the operator wear the battery on his belt to allow a little larger capacity without increasing the "gun" weight and size?

 

[MintJulep]

I'm not sure if there is a fluid available with the correct saturation curve to do this or not, but how about this for a wacky idea....

Piston in a cylinder. One end of cylinder sealed from atmosphere and filled with a refrigerant type fluid. Other end of cylinder fitted with appropriate intake and discharge valves.

Cool the refrigerant, its saturation pressure drops (ideally below atmospheric pressure) pulling the piston towards that end of the cylinder and filling the other with air through the intake valve.

Heat the refrigerant. Saturation pressure rises, pushing the piston and compressing the air.

Essentially this is a steam engine driving a reciprocating compressor. Just no rotating parts.

 

[Pekelder]

Why don't you use a spring-loaded device. You will have to 'recharge' it, but that can be done by hand. The storred energy is contained until use, and can be very powerfull. With it, you can drive a piston directly, giving you the power (pressure and volume) you need free to choose.

Regards
Pekelder

 

[RichLeimbach]

I agree with IRStuff. This is not something we can discuss effectively without knowing: The volume of air needed, the cycle rate, the necessary efficiency, and other details. Can you give some more info on this?

 

[avjJOE]

What is the spefic volume of air required? If it is small then you may be able to use the equilvent of a taser to superheat air or ni-crome wire

 

[Azraq]

Before I begin I'd like to qualify my thoughts by asking all the questions previously asked and by stating that I'm only a Sophmore in college, but Pekelder seems to have a valid point that I would extend to include a hand pump type device like a pneumatic BB gun. I'm not sure of the psi but they'll fire a projectile at a couple hundred ft/s.
Cheers
Azraq