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  1. #1
    Join Date
    Aug 2006
    Posts
    2,583

    Angry

    I lost my paper with the discharge superheats for different compressors, I'd put together over the years. Does anyone know of a place I could get this info, anyone in the DC area I gave a copy to? Also lost my inverted subcooling/super heat chart for R22. Gave that out too. Checked my computer and they aren't there either.

  2. #2
    Join Date
    Aug 2000
    Location
    Austell, Ga.
    Posts
    1,294
    Madhat;
    Discharge Superheat on some systems are as diverse as the applications involved..
    Some of the "Freeze-Dry" units used by NASA to dehydrate foods are either Carrier or York Compound compressors with up to 4 stages of compounding and uses up to 3 "De-Superheating" expansion valves. Some of these units use R-502 and will scare the Be-Jeezus out of any mechanic should he walk in and see the suction pressure in a 16" vacuum...
    Without the "De-Superheaters" working, the discharge temp's would be in excess of 350 deg F...
    No lubricant or discharge valve material could possibly take that..
    If you are referring to a single stage recip. compressor without unloading in a comfort cooling application most manufacturers would like to see 15-25 deg.f as a target for R-22..
    Since the primary factors involving Disch-Superheat are;
    1- Suction Superheat
    2- Compression Ratio
    3- Discharge Valve Integrity
    As suction pressures drop the DS will rise accordingly due to the higher CR..
    Crack a discharge valve reed or ring and the DS can rise to over 300 deg. f...(For a very short time)
    In short, the manufacture of any given piece of equipment will state a given DS for a "Certain" operating condition....
    Applications as well as operating conditions are surely to diverse for anyone to state a fixed amount of DS on "Any" type-make-model compressor....
    Methinks I went off on a tangent there...but Hey!!!!
    I'm a member of AARP now....
    Us "AARPIES" have that priveledge.....
    Ain't "None" of us as smart as "All" of us..

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