单项选择题
A.change from blue to orange B.‘flare up’ and remain lighted C.probably go out D.stay blue
Before charging a refrigeration unit, the refrigerant c...
单项选择题Before charging a refrigeration unit, the refrigerant charging lines should be（）
A.flushed with clean refrigerant oil B.purged with the refrigerant C.washed with an ammonia and alcohol solution D.grounded to compressor
In the presence of an open flame or hot surfaces, chlor...
单项选择题In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decomposes and from （）
A.petroleum crystals B.phosgene gas C.water vapor D.carbon monoxide
In an operating refrigeration system low on refrigerant...
单项选择题In an operating refrigeration system low on refrigerant, a liquid line sight glass will（）
A.be clear B.be blue C.be light green D.show bubbles
