Refrigerant filled amount detector of refrigerating plant

PURPOSE:To correct the shortage in filled refrigerant by detecting the shortage in refrigerant filled in the refrigerant circuit of a refrigerating plant. CONSTITUTION:The liquid pipe of a refrigerant circuit 14 between a condenser 6 and a motor-driven expansion valve 13 and the suction side of a compressor 1 are connected by a bypass 40 via a pressure reducing mechanism 41, and a closing mechanism 42 is provided to open and close the bypass 40. A check operation controller 51A closes the expansion valve 12 and opens the opening mechanism 42 of the bypass 40 to start operation. When the temperature of refrigerant at the downstream side of the pressure reducing mechanism 41 of the bypass 40 becomes higher than a saturation temperature equivalent to the evaporation pressure in the refrigerant circuit by a specified value, a signal output device 52A outputs a refrigerant shortage signal. Thereby, liquid refrigerant is stored in a liquid line and the shortage in the filled refrigerant is accurately detected in a state the maximum amount of refrigerant is required.