Escaped Crankcase Oil Can Cause Problems, Coat Evaporator Tubes

摘要

Little by little, a compressor's lubricating oil will eventually escape the compressor's crankcase and enter the system's tubing. Hopefully, this escaped oil will slowly find its way through the condenser, receiver, liquid line, metering device, evaporator, and suction line and end up back in the compressor's crankcase. It is the velocity of the refrigerant traveling through the system, as well as the piping arrangement, that brings the oil back to the compressor's crankcase. That is why it is so important to have the proper line and coil sizes to support the correct refrigerant velocity for proper oil return. Just as important for proper oil return to the compressor are properly sloped lines and properly located P-traps. Ideally, the perfect situation for the oil in a refrigeration or air conditioning system would be for it to stay inside the compressor's crankcase to lubricate the compressor's moving parts. However, because of ever-changing heat loads on the system and varying system conditions caused from refrigerant undercharges or overcharges, inoperative valves, faulty or misadjusted metering devices, dirty condensers, dirty evaporators, fan motor failures, or plugged filter driers, this is unlikely to happen in the real world.