Air compressor Question

[79camaro2001]

If Displacement CFM is measured by

Displacement CFM= (Area of Piston X Length of Stroke X RPM X Number of Piston)/1728

Would it be logical to think if you connected 2 air compressor that gives 5cfm at 90psi, it would give 10cfm at 90psi?

I was just thinking about this and was wondering if someone could confirm this.

[Gary S]

Your formula won't quite work because you need to factor in efficiency too. Efficiency is why you get more CFM at 40psi than you get at 100psi. The harder the pump works against the compressed air, the lower the efficiency goes.
But, yes, connecting two compresssors together will give you more CFM. If they are the same size and compress at about the same rate, and if they start at the same point, you will gain CFM.
However, if one compressor starts running at 80psi and the other one doesn't start until 70psi, you won't get them both running at the same time unless you use enough air to force the 80psi one below 70psi while it running so they both kick on.
Try it. It shouldn't hurt anything. You will most likely have to play around with the low pressure settings to get them close enough to force both of them to run.

[79camaro2001]

Originally Posted by Gary S

Your formula won't quite work because you need to factor in efficiency too. Efficiency is why you get more CFM at 40psi than you get at 100psi. The harder the pump works against the compressed air, the lower the efficiency goes.
But, yes, connecting two compresssors together will give you more CFM. If they are the same size and compress at about the same rate, and if they start at the same point, you will gain CFM.
However, if one compressor starts running at 80psi and the other one doesn't start until 70psi, you won't get them both running at the same time unless you use enough air to force the 80psi one below 70psi while it running so they both kick on.
Try it. It shouldn't hurt anything. You will most likely have to play around with the low pressure settings to get them close enough to force both of them to run.

I figured it would be around 75-85% efficiency at the most. But I just didn't throw that in the mix just yet.

I figured if I ran them together, I would use a single pressure control, that way they will come on at the same pressure instead of doing what you mentioned if running off 2 controls.

I got these 2 compressors at home and they are both the same size and such, but they are no bigger then 5 - 6cfm at 90psi.

If I can get it up to 7 -8cfm I can live with it. Just have to wire up a seperate breaker for each compressor.

[BusDriver]

Yes, if you wire it correctly that will work fine. Just make sure you don't exceed the pressure of the tanks or pums, but if they are the same then just wire them up to the same control, sperate breakers, and go to it.

[Rick WI]

Yes, multiple compressors are setup all the time in industrial applications. Piping needs to be parallel and they should feed into one receiver. You also need to set controls so one doesn't fight the other.