To detect generating state of flash gas in detail with high accuracy.
A refrigerant pipe between a condenser and a pressure reducing unit is provided with a sight glass 7 having an inspection hole for confirming the state of refrigerant flowing through the pipe, a light emitting section 7E provided in the sight glass 7 and emitting light to traverse the refrigerant flowing through the pipe, A light receiving section 7F for receiving light from the light emitting section 7E and outputting a light receiving signal, and means for making a decision whether the quantity of refrigerant is deficient or not based on at least two values of the intensity of the light receiving signal, variation width, inclination of variation and the number of times of oscillation. Since generating state of flash gas can be detected in detail, the decision can be made with high accuracy whether the quantity of refrigerant is deficient or not.
ASAMI KAZUYUKI
TANIGUCHI IKUTAMI
HASEGAWA SETSU
OIWA AKIRA
IDA YOSHIO
