计量检定人员是指经（），持有计量检定证件，从事计量检定工作的人员。A．考核合格B．计量行政部门批准C

Sweating of the refrigeration system compressor crankcase is caused by_______ .

A.too much superheat

B.insufficient superheat

C.suction pressure too low

D.excessive refrigerant returning to the compressor

Excessive oil foaming in the crankcase of a refrigeration compressor can result in _____.

A.overheated compressor bearings

B.excess lube oil viscosity

C.carbon deposits on the compressor piston rings

D.wax crystals forming in the lubricant

Foaming of the oil in a refrigeration compressor crankcase is caused by _____.

A.refrigerant boiling out of solution from the lube oil

B.liquid refrigerant flooding the compressor and system

C.lube oil viscosity being reduced by refrigerant dilution

D.compressor suction pressure suddenly increasing

A.a shortage of refrigerant in the system

B.air in the system

C.an accumulation of liquid refrigerant in the crankcase

D.a shortage of oil in the crankcase

A.compressor damage from improper lubrication

B.refrigerant absorption by the lubricant

C.increased viscosity in the lubricant

D.carbon deposit on the compressor suction valves

A.high discharge pressure

B.frosting of the crankcase

C.high temperature of the overboard water

D.low suction pressure of compressor

A.insufficient lube oil circulating through the system

B.excessive circulation of lube oil through the system

C.insufficient refrigerant in the system

D.an overworked compressor

A.has run continuously for a long period

B.suction pressure is below normal

C.oil level is below normal

D.starts after a long idle period

A.add refrigerant to the system

B.adjust the thermal expansion valve to the proper setting

C.adjust the float valve to the proper holding pressure

D.open the hand expansion valve

A.open-type

B.hermetic

C.semi-hermetic

D.all the above