The compressor must be selected for the capacity required at the desired operating conditions in accordance with the manufactures recommendations for the refrigerant to be used. Standard Copeland single stage compressors are approved for operation with a given refrigerant in one of the following operating ranges.
( Evaporating Temperature )
* High Temperature 45° F. to 0° F.
or 55° F. to 0° F.
* Medium temperature 25° F. to - 5° F.
* Low Temperature 0° F. to -40° F.
*Extra Low Temperature -20° F. to -40° F.
Operation at evaporating temperature above the approved operating range may overload the compressor motor. Operation at evaporating temperature below the approved operating ranger is normally not a problem if the compressor motor can be adequately cooled, and discharge can be kept within allowable limits. Evaporating temperatures below -40° F. are normally beyond the practical lower limit of single stage operation because of compressor inefficiencies and excessive discharge gas temperatures. Because of problems of motor cooling or overloading, some motor-compressors may have approval for operation at limited condensing or evaporating temperatures within a given range, and if so, these limitations will be shown by limited performance curves on the specification sheet.
A given compressor may be approved in two different operating ranges with different refrigerants, for example, high temperature R-12 and low temperature R-502. Since the power requirements for a given displacement with both R-22 and R-502 are somewhat similar, in some cases a compressor may be approved in the same operating range for either of these refrigerants.
Two stage compressors may be approved for evaporating temperatures as low as -80° F., but individual compressor specifications should be consulted for the approved operating range.
Operation at temperatures below -80° F. is normally beyond the practical efficiency range of Copeland two stage compressors, and for lower evaporating temperatures, cascade systems should be employed.
Copeland motor-compressors should never be operated beyond published operating limits without prior approval of the Copeland Application Engineering Department.
Extra
Danfoss focuses on providing energy efficient, sustainable and smart refrigeration compressors for a varied range of commercial applications such as cold rooms, display windows, ice making machines, glass door merchandisers, process cooling etc. Their qualification with lower GWP refrigerants make them compliant with refrigerant regulations such as F-Gas in Europe.
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