Which of the listed statements describes the reason why oil foaming occurs when starting a refrigeration compressor?

Correct Answer: Option B — This condition is the result of the sudden low-pressure created in the crankcase at start up causing the release of refrigerant absorbed within the oil.

Refrigerant gas readily dissolves into compressor lubricating oil under high pressure and low temperature. Upon start-up, a sudden crankcase pressure drop causes this refrigerant to boil out rapidly, resulting in severe oil foaming.