2.7 Discharge Line Check Valve
Compared with vertical type compressor, the motor of horizontal type compressor is more inclined to be
immersed by refrigerant, which will result in lower insulation resistance value and higher leakage current
readings. This is not a safety issue and the insulation resistance value will be back to normal after a short
period operation to redistribute the refrigerant through the system.
In order to prevent refrigerant migration to compressor during off cycle, a check valve should be installed in
discharge line. The leak rate of check valve should be qualified by testing.
2.8 Suction Line Strainer
To prevent foreign particles coming in the compressor inside, it shall install the strainer with screen on the
way to suction line piping. The strainer shall be more than 30mm in diameter and a screen mesh size of 100.
In case that the suction line has an accumulator with screen, the strainer will not be required.
A suitable sized filter dryer should be used to ensure the low degree residual moisture level in the refrigerating
circuit, the molecular sieves type is recommended.
2.10 Oil separator
An oil separator is recommended to separate a major part of oil from compressor discharge gas and return it
directly to compressor crankcase. The functions of oil separator including:
1) Improve the oil management and reliability of compressor;
2) For inverter compressors, the oil flow rate increases when rotation speed is high, more oil leaving
compressor and lower the efficiency of heat exchanger, which will result in lower cooling capacity of
system. In this case the use of oil separator will give a notable improvement for system performance；
3) Panasonic horizontal scroll compressors are designed with high pressure shell, the oil return pipe
should go through capillary tube and connect with suction tube (before the suction accumulator) ；
4) A centrifugal type oil separator is recommended which has a stable oil separation rate in variable
refrigerant flow rate conditions.
Figure 2-1 Suction Accumulator