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For all new systems with ZB*KAU compressors and a
reduced oil filling, it is mandatory to check and test the
oil distribution and compressor oil filling using a
dedicated sample compressor equipped with an
external oil sight tube.
The oil tests for compressors with an external oil sight
tube must be carried out by the system designer in the
lab. This will allow to investigate the oil return behavior
to the compressor. In case some oil remains in the
system, e.g., in the tubes, heat exchangers or other
components, oil top-up is required. A sufficient oil level
must be present in the compressor at all times to ensure
proper compressor reliability.
Test procedure
•
Before first compressor start, mark the 12oz (355
mL) minimum filling level and the 16oz (473 mL)
filling level on the external oil sight tube. The
distance to the markings can be measured from the
top of the compressor footplate
Figure 19 - ZB*KAU with external oil sight tube
© 2018 Emerson Climate Technologies, Inc.
Appendix B: Oil Filling Test for new applications
Figure 20 - Markings on the external oil sight tube
•
Start and run the system until it reaches stable
conditions, then run at stable conditions for a
minimum of 15 minutes. Stop the compressor and
read the oil level during standstill. Any oil level
between 12oz (355 mL) and 16oz (473 mL) is in the
nominal range and is acceptable.
•
Always check the level in the external oil sight tube.
Once the level falls below the 12oz (355 mL)
marking, stop the compressor immediately. Re-
check the oil level after stopping. Any oil level below
the 12oz (355 mL) marking is not acceptable.
•
Top-up some oil if necessary and record the amount
of topped-up oil. This could be the reference for all
future systems with the same design. Perform the
test anew to check the oil return behavior again, as
described above.
•
Repeat the test at different operating conditions,
starting with the main operating point. Test different
operating points in the corners of the operating
envelope as well. Refer to Figure 21 for main
operating point, high load HL, maximum differential
28
AE4-1431 R1
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