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  1. #1
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    Aug 2004
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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?

  2. #2
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    Aug 2003
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    Take the suction pressure reading on your gauge and add 14.7 psi. Do the same for your discharge pressure reading. Take these two new numbers and divide them into one another. The answer is your compression ratio.

    The 14.7 is atmospheric pressure at sea level, which makes your suction and discharge pressure readings "absolute" vs. "gauge".
    Building Physics Rule #1: Hot flows to cold.


    Building Physics Rule #2:
    Higher air pressure moves toward lower air pressure


    Building Physics Rule #3:
    Higher moisture concentration moves toward lower moisture concentration.

  3. #3
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    Unhappy 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. #4
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    Apr 2002
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    Omaha, NE
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    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

  5. #5
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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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