# compression ratio

• 06-12-2005, 08:35 PM
thewoodman
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?
• 06-12-2005, 08:39 PM
Shophound

The 14.7 is atmospheric pressure at sea level, which makes your suction and discharge pressure readings "absolute" vs. "gauge".
• 06-12-2005, 09:09 PM
thewoodman
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.
• 06-12-2005, 09:34 PM
snewman24
Re: compression ratio
Quote:

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
• 06-12-2005, 09:44 PM
thewoodman
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.