Suction line accumulators are widely used in modern vapor compression refrigeration systems to protect the compressor from mechanical damage due to liquid refrigerant entering the suction port. Different types of compressors, such as reciprocating, rotary vane, centrifugal, and rotary screw designs vary in their ability to handle liquid refrigerant. One thing is certain, however, refrigeration compressors are designed for compression of gas only, and systems should be so designed and operated that only vapor enters the compressor from the system. Since it is almost impossible to completely eliminate liquid slop-over from the system evaporators under all operating conditions, a wise investment is the installation of a suction trap to remove the liquid before it reaches the compressor.

Accumulators vary considerably in size, shape, and construction. In many instances, they are designed for more than one function, e.g., desuperheater, pump receiver, low pressure receiver, oil separator.

The fundamentals governing the design of the liquid trap are not complicated. Three basic parts to the design are determination of the required surge volume, the required liquid-vapor separation volume, and the method of eliminating excess accumulated liquid.