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I remember reading that you can figure the compression ratio by using a certain formula. But I don't remember how?
something about dividing the low side by the high side to figure the percentage. To see if the compressor is working at 40% capacity or 90%, or whatever. To help the technition determine the volumetric efficency. Is it difficult to figure? And is really that simple?

The 14.7 is atmospheric pressure at sea level, which makes your suction and discharge pressure readings "absolute" vs. "gauge".

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## compression ratio

ok shophound, thanks, but lets see.. if I have 70psi on suction and say 220 discharge...add 14.7 to each to get pounds per square inch absolute..Ok...Divide 84.7 by 234.7 = .36 or divide 234.7 by 84.7 and get 2.77?? What is the ratio?? I don't get it.

4. ## Re: compression ratio

Originally posted by thewoodman
ok shophound, thanks, but lets see.. if I have 70psi on suction and say 220 discharge...add 14.7 to each to get pounds per square inch absolute..Ok...Divide 84.7 by 234.7 = .36 or divide 234.7 by 84.7 and get 2.77?? What is the ratio?? I don't get it.
He meant the absolute discharge divided by the absolute suction....so in your example it's 234.7 ÷ 84.7 = 2.77

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## compression ration

ok. then it would be 2.77:1
This would indicate the pumping ratio...not the compression ratio. So this tells me the compressor is pumping 2.77 to 1 or almost 3 to 1 discharge per suction.

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