Air Flow - Need 1/2 CFM at 5-8 PSI

Sorry, something like a hair dryer will not develop even a few PSI.

On the positive side, that low of a compressed air requirement can be provided by even the smallest portable compressor. The portable single phase units that plug into house current will do it. I quickly checked and even some 12 Volt units that plug into your car can do it.

You may be able to charge up a portable tank and carry it to point of use depending on how long you need to operate.

How about using the spare tyre of the car! I know a bloke who used a spare tyre for air brush work! Put a cheap regulator on the valve and off you go! Or if that isn't enough quantity of air, use a vacuum cleaner in reverse, better than messing up the wife's hair drier!

Shame about the hair dryer, I thought that taking the large area air flow from the dryer into a small delivery pipe would give me some pressure.

Good thoughts about using a tyre inflater, I've got a jump starter with a compressor built in that I could have a play with over the weekend. Maybe with a reservoir that could do it.

The ½ CFM sounds like just a gentle breeze, is that right?

Just a little more information about using a hair dryer.

It is common for commercial centrifugal air movers to operate in the 1 to 3 inches of water range. Three inches of water is .11 psi. I suspect this or less is where a hair dryer would be. Higher pressure commercial air movers would be in the 15 inches of water and up. That is equal to .4 psi. I have a regular centrifugal fan continuously operating at 20 inches of water (.72 psi). Of coarse there are centrifugal air movers designed to operate at much higher pressure (a turbocharger for example) but they are the exception.

How about an air pump for a hobby aquarium?

While the internet is full of places to order, tech data is pretty scarce. But offhand, I would guess outflow and pressure are somewhere around your requested numbers.

Suggest something similar to one of these low end compressors.

http://www.safety-devices.com/12-volt-air-compressor.htm

Shop around and you might be able to find some at about 1/2 the cost of the ones listed above. Hobby air brush compressors are also an option.

Just so you know "how much" 1/2 CFM is-

If you build a compressor with a 1.00 inch diameter cylinder that is 4.00 inches long and the piston has a 2.00 inch stroke running at 550 RPM, you will produce 0.500 CFM of air at 7.35 PSIG- a 5.00 inch long cylinder will yield 5.88 PSIG discharge.

Most of the devices discussed, including the fish tank pump, will likely not produce the 5-8 PSIG that you require. They are designed to operate under about 2 feet of water- or less than 1 PSIG static pressure. Even a 0.5 PSIG loss through an air stone will not be even close.

A human being breathes out 1/4 cfm at rest.

An aquarium pump is a kind of diaphragm compressor. Versions to suit your capacity are available.

bioramani

Search for Thomas Diaphragm Pumps.I had to have a small compressor for a bubble tube controller, at 20 feet of water pressure. Reasonably priced, quiet, durable,and easy to repair if needed.

I never did get to play with the tyre inflater, instead I spent the weekend finding & fixing a water leak in my kitchen.

I've managed to try out the equipment by borrowing a bottle of nitrogen gas which worked OK.

Thanks for all the suggestions.

So the missisus hair drier got away unscathed!!

I got lucky yesterday at the local boot sale & picked up a small electric compressor for £7. 116psi max with 7cfm & a 6 litre tank. It works fine although I had to drain a lot of crap from the tank.

Turned out fine again!!