# How we increase the pressure of a air compressor

1. May 30, 2007

### ahsuu

my question is that..

is there any way to increase the pressure from 25 psi to 125 psi...is the volume is 5.2m3/min...

2. May 30, 2007

### FredGarvin

It depends entirely on the compressor. Can the compressor physically survive an output pressure of 125 psi?

3. May 30, 2007

### Danger

Also the reservois, if one is used, and the lines. Make sure that you stay well below the burst pressure.
May I ask why you want to do this, rather than just replace the compressor with a higher-rated unit? About the only 35psi compressor that I've seen was a really cheesy little thing that plugs into the lighter socket in a car for emergency tire inflation. I've never even seen one that was only 25 psi.

4. May 30, 2007

### FredGarvin

It really depends. If the demand is high enough the compressor may keep up with the volumetric requirement, but not at a high enough pressure. If this is the case, then one needs to either increase the backpressure on the system or reduce the demand.

5. May 30, 2007

### Q_Goest

Hi ahsuu,
I think what you're saying is you have a 25 psi source of air in a process that you'd like to increase to 125 psi at a flow of 5.2 m3/min. Assuming compressor displacement is 5.2 m3/min (500 SCFM), that becomes a 60 to 75 hp machine. That's not a particularly large machine, but depending on who you talk to, it's fairly substantial. (Note, you should always put down normal or standard conditions, or better yet just use mass flow rate. Actual displacement is always more confusing and will inevitably get you in trouble when specifying a machine.)

Screw machines would be the best solution for this size of air compressor. It's a bit large for a recip and a bit small for a centrifugal, though I suspect that with the overlap, you could find both recips and centrifugals capable of doing this duty. Regardless, I'd suggest a screw machine.

Unfortunately, you're asking for a special, because the suction pressure is above atmospheric. That isn't to say you shouldn't pursue that option, but at least consider alternative ways of doing this. Contact the screw machine manufacturers to discuss 25 psi inlet but then consider just regulating the air down to atmospheric, or better yet just using atmospheric air, then compressing to 125 psig. The reason to do this is that, although you'll loose some efficiency because you have to now increase pressure from 0 to 125 psig, you can get a screw machine off-the-shelf, something mass produced. It will be a lot cheaper on capital cost. Something capable of an inlet pressure of 25 psi is an odd-ball, and may have to be specially made or a standard machine would need to be modified.

Note you're roughly doubling the power required by using atmospheric inlet pressure for any given mass flow rate.

Here's a short list of different manufacturers you might check out.

Corken (recips)
Ingersol Rand (all kinds)
Burton Corblin (recips)
Any screw compressor manufacturer (I-R, Atlas Copco, Keiser, etc...)

Also, if you're in the US or Canada, I'd suggest using ThomasNet for searches on manufacturers like this. Try them here:
http://www.thomasnet.com/