Abstract: The capacity of a compressor (21) in cleaning operation is set based on a Froude number Fr. The Froude number Fr expresses a ratio of an inertial force of a gas refrigerant flowing through a gas side communication pipe (70) to a gravity working on a liquid in the gas side communication pipe (70). The capacity of the compressor (21) in the cleaning operation is set so that the Froude number Fr is larger than 1, whereby the inertial force of the gas refrigerant flowing through the gas side communication pipe (70) becomes larger than the gravity working on the liquid in the gas side communication pipe (70) which contains mineral oil and foreign matters. In this connection, the liquid containing the mineral oil and the foreign matters is pushed up by the gas refrigerant even in a perpendicularly extending portion of the gas side communication pipe (70).

Abstract: A method is disclosed that makes it possible to reduce the amount of refrigerant used and shorten the amount of time over which the new air conditioner must be run in a refrigerant pipe washing mode when an air conditioner that used a mineral-oil-based refrigerant oil is updated to or replaced with an air conditioner using an HFC refrigerant as the working refrigerant and the existing refrigerant piping is reused as is. Thus, the existing refrigerant piping of the air conditioner that used a mineral-oil-based refrigerant oil is reused in the air conditioner that uses an HFC refrigerant as the working refrigerant, the by washing the refrigerant piping using a cleaning agent comprising an HFC refrigerant containing at least 40 wt % of R32 to remove residual refrigerant oil in the refrigerant piping.

Abstract: A refrigeration apparatus is provided with a vapor compression type refrigerant circuit. With this apparatus, reliability from the standpoint of the pipe cleaning mode of the apparatus is improved. The air conditioning system has a main refrigerant circuit that has a compressor, a heat-source-side heat exchanger, and a user-side heat exchanger. The air conditioning system also has a contaminant collecting device provided on the intake side of the compressor (21). The contaminant collecting device is equipped with a contaminant collecting container, an inlet pipe, an outlet pipe, and a main opening/closing device. The contaminant collecting container separates contaminants from refrigerant flowing in the intake gas pipe toward the compressor when the refrigerant is directed through it. The inlet and outlet pipes are each provided with a return preventing shape for preventing contaminants that have accumulated inside the pipes from returning to the intake gas pipe.