| 摘要 |
A piping cleaning system switches over a four-way switching valve 43 of a heat pump circuit 200 so that two transfer heat exchangers 25, 26 are operated alternately as a cooling device and a heating device, by which a cleaning refrigerant in a cleaning circuit 2 is circulated through a gas line 3 and a liquid line 5. During this cleaning operation with the cleaning refrigerant circulated, when the cleaning refrigerant runs short in amount, a solenoid valve SV3 is opened so that cleaning refrigerant of the refrigerant cylinder 71 is resupplied through a refrigerant resupply line 72 to either one of the transfer heat exchangers 25 or 26 that is cooling. On the other hand, when the cleaning refrigerant is excessive, a solenoid valve SV4 is opened so that the cleaning refrigerant is returned to the refrigerant cylinder 71 through a refrigerant bleed line 73. Thus, the amount of cleaning refrigerant can be maintained at an appropriate level.
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