Brochure

34 AB218186428184en-US1501
GENERAL INFORMATIONPRODUCT INFORMATIONINTEGRATION INTO SYSTEMORDERING INFORMATION SYSTEM DESIGN
Manage off cycle migration
R
Requirement
Evaluate the risk
Off -cycle refrigerant migration happens:
• when the compressor is located at the coldest
part of the installation, refrigerant vapor
condenses in the compressor.
• or directly in liquid-phase by gravity or pressure
difference.
When the compressor restarts, the refrigerant
diluted in the oil, or stored in evaporator,
generates poor lubrication conditions and may
reduce bearings life time. In extreme situations,
this leads to liquid slugging that can damage
compression scrollset.
• Compressor can tolerate occasional flooded
start, but it should remain exceptional situation
and unit design must prevent that this situation
happen at each start
• Right after start, liquid refrigerant must not flow
massively to compressor
• The charge limit is a threshold beyond some
protective measures must be taken to limit risk of
liquid slugging and extreme dilution at start.
(refer to charge limit table in section “Manage
superheat”).
Use the table below in relation with the system
charge (refer to charge limit table in section
“Manage superheat”) and the application to
quickly define necessary safeties to implement
and test to perform:
BELOW cHargE Limit aBOVE cHargE Limit
Non split No test or additional safeties required
• Crankcase Heater*
• Migration test
• External Non Return Valve
Split
Since each installation is unique, no test can fully evaluate off-cycle migration, therefore
the following safeties are required:
• Crankcase Heater *
• Liquid Line Solenoid Valve**+ pump-down cycle***
• (Internal Non-Return Valve integrated)