A.Centrifugal
B.Reciprocating
C.Gear
D.Rotary
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A.a high suction head
B.rotating rings
C.badly worn bearings
D.a loose stuffing box gland
A.solenoid valve to seize
B.compressor to hunt
C.formation of flash gas in the liquid line
D.expansion valve to freeze open
A.insufficient condenser cooling water
B.excessive condenser cooling water
C.air in the refrigeration system
D.excessive refrigerant in the system
A.Thermal expansion valve frozen open
B.Suction gas heat exchanger bypassed
C.Condenser clogged or fouled
D.High pressure cutout switch inoperative
A.noise and vibration
B.an increase in discharge pressure
C.an increase in suction pressure
D.lifting of the relief valve
A.insufficient cooling water flow to the condenser
B.a low refrigerant charge in the system
C.the liquid valve is open too much
D.high evaporator superheat
A.dead band action
B.neutral zone action
C.range
D.on-off action
A.cavitation
B.electrolysis
C.abrasion
D.corrosion
A.the relief valve should open before the high pressure cutout
B.the relief valve should open and allow the excess refrigerant to flow to the receiver
C.the high pressure cutout switch should operate before the relief valve opens
D.you should close in on the suction valve
A.cause of salt contamination
B.location of salt water contamination
C.chemical makeup of feed-water
D.level of alkalinity in condensate
最新试题
One cause of high head pressure occurring in a refrigeration system can be （）.
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
Low compressor head pressure in a refrigeration system can be caused by（）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
The major source of chemical contaminants in hydraulic fluid is （）.