The function of a Liquid Level Switch is detect and monitor liquid levels. Applications The level switch can be installed in a number of locations in the refrigeration system such as liquid receivers, suction line accumulators and compressor crankcases. The range is designed for use with HCFC, HFC, CO2 and ammonia refrigerants, along with their associated oils. A 1” NPT level switch is recommended for ammonia applications. For other refrigerant/oil combinations, please contact Henry Technologies.