Compressor Output vs. Elevation Change

[bean10]

Can someone provide the equations to determine the effect elevation change has on compressor flow rate?

I have a compressor that provides 100 CFM at 1000 RPM at standard ambient conditions and need to calculate what the flow rate will be at an altitude of 10,000 feet where the air is less dense.

I cannot find this information anywhere else on the web.

 

[TD2K]

What type of compressor? I'm assuming at 1000 rpm it's some type of recip compressor.

In that case, the change in capacity will be relative to the air pressure at 10,000 feet (and inversely proportional to temperature if that's a factor) versus the pressure at sea level. Roughly, the compressor will deliver 2/3s of what it will at sea level.

The compression ratio for the compressor will also increase (if you keep the discharge pressure constant) due to the lower suction pressure and you will want to ensure you don't exceed the allowable discharge temperature.

 

[tonyh]

To put it another way, to a first approximation the machine will deliver the same suction volume of 100cfm, but the mass flow will drop in proportion to the inlet density.