In the event of noise or vibration from gas pulsations, discharge mufflers are recommended and must be installed for the free draining of oil.
recommended and must be installed for the free draining of oil. As previously stated, when compressors are idle the oil adhering to the inner surfaces of the discharge line risers will drain to the bottom of the risers. With a 3 m riser, plus the discharge muffler, the amount of oil can be quite considerable.
It is therefore advisable to loop the discharge line towards the floor to form a trap so that oil cannot drain to the compressor head. This trap will also collect any liquid refrigerant which may condense during the off cycle. It is especially important when the discharge line is in a cooler location than the condenser/receiver. Mufflers are normally installed vertically near the condensing unit to provide efficient oil movement. Figure 76 shows a discharge muffler installed in a discharge line loop.
