Superheat Requirements; Figure 1 - Extended Medium Temp Operating Envelope For Zb*Kau Compressors; Figure 2 - Oil Filling And Minimum Acceptable Oil Level - Emerson Scroll ZB*KAU Application Manuallines

2.2.5. Superheat Requirements

To determine if liquid refrigerant is returning to the
compressor is recommended to accurately measure the
temperature difference between the compressor oil
crankcase and the suction line. During continuous
operation we recommend that this difference be a
minimum of 50°F (27°K). This "crankcase differential
temperature" requirement supersedes the minimum
suction superheat requirement in Section 2.2.3. To
measure oil temperature through the compressor shell,
place a thermocouple on the bottom center (not the
side) of the compressor shell and insulate from the

Figure 1 - Extended Medium Temp operating envelope for ZB*KAU compressors

© 2018 Emerson Climate Technologies, Inc.

Figure 2 - Oil filling and minimum acceptable oil level

ambient.
During rapid system changes, such as defrost or ice
harvest cycles, this temperature difference may drop
rapidly for a short period of time. When the crankcase
temperature difference falls below the recommended
50°F (27°K), our recommendation is the duration should
not exceed a maximum (continuous) time period of two
minutes and should not go lower than a 25°F (14°K)
difference.
Contact your Emerson
representative regarding any exceptions to the above
requirements.
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AE4-1431 R1
Climate Technologies