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Compressor Overheating and Rfrig. Oil

Harvey RamerHarvey Ramer Posts: 1,016Member ✭✭✭
Here is a good read. It explains in great detail about the importance of controlling the comp discharge temp and what happens if you don't.



Harvey
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Compressor Overheating.pdf
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Comments

  • TechmanTechman Posts: 2,057Member ✭✭✭
    overheating

    For those of use who can't read , do tell use what that magic # is, Harvey!!So , is the SH of the evap, critical? the SH of the Suction Line? the SH's of the comp critical? or the TOTAL SH in the discharge line? Good thread Harvey!!!!!!!!!!!!!!
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  • Harvey RamerHarvey Ramer Posts: 1,016Member ✭✭✭
    Put your glasses on Terry!

    It's a fun read!



    I would say that the highest discharge temp that I am inclined to be comfortable with is right around 230°F. This would be the measured temp. The actual discharge temp will be 50° - 75° higher than that. That would put the actual discharge temp up around 280° - 305°.

    As the document states; Refrigeration oils have been highly refined in an effort to elevate the temperature at which chemical decomposition will occur. As such, they are vulnerable to losing the lubrication film necessary to prevent metal to metal contact between bearings and journals, or piston rings and cylinders, prior to the temperature at which decomposition begins. With mineral oil this will occur approximately between 310ºF and 330ºF. When these temperatures are achieved, the probability of extreme piston and ring wear is imminent.



    ALL THE SH's ARE CRITICAL!! The comp discharge temp is a product of "Heat of Compression" and all the combined SH's, including the evaporator. We can do nothing about the heat of compression, but we can run a "tight ship" on the rest of the SHs.



    Another point that was of interest to me;

    Chemical decomposition: This happens at elevated temperatures, and is accelerated in the presence of other contaminants such as air or water. 18 is an important number to remember, for the rate of chemical reaction doubles with every 18ºF temperature increase.* For example, a chemical reaction that takes 10 years to complete at 100ºF, will only take 5 years to complete at 118ºF. At 136ºF it would be complete in 2-1/2 years, and so forth. The process by which the refrigerant and/or oil chemically breaks down can occur in a matter of seconds if there have been enough 18° temperature increases.



    Good stuff to know!!



    Harvey
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  • TechmanTechman Posts: 2,057Member ✭✭✭
    overheating

    Geez Harvey, I asked you to tell us, you SHOUTED that info out to us . GOOD INFO, REAL GOOD . Now how many really care? ALL OF US SHOULD CARE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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