Protection against liquids
Automatic Operation of Refrigeration Equipment

When the compressor stops, refrigerant vapours returning to the crankcase can dissolve in the oil. On subsequent start-up, the reduction in crankcase pressure causes the oil/refrigerant mixture to degas. This leads to the formation of foam, which in large quantities can rise in the cylinders. This foam, formed by splashing in the crankcase, can be seen in figure 25 . In a reciprocating compressor, this is the type of oil hammer that can cause discharge...