A.increase the flow of the cooling water through the condenser
B.adjust the high pressure cutout to maintain the desired pressure
C.open the hot gas bypass temporarily to reduce capacity
D.purge non-condensable gases to reduce the excess pressure
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A.Special tools are required for lapping or grinding
B.It is impossible to throttle flow with a butterfly valve
C.To close the valve, it is only necessary to turn the handle a quarter of a turn
D.The butterfly valve should never be used in a freshwater system
A.closely observe the pump discharge temperature
B.close off the discharge valve, and watch for a rise in pressure
C.momentarily close off the suction valve, and watch for a rise in pressure
D.use a clamp on ammeter and compare the readings to past records
A.removing all but the frictional load during starting
B.relieving intercoolers of high temperature buildups
C.providing high starting torque in the drive motor
D.seating valve plates during compressor shutdown
A.loose expansion valve control bulb
B.low differential setting on the H-Pcutout
C.blown fuse in the motor circuit
D.faulty suction pressure regulator
A.prevent an internal explosion in the pump when it is overheated
B.enable a visual inspection of the pump while it is running
C.insure a proper alignment of the pump coupling to the driver
D.accommodate for friction between the impeller and the easing
A.explosive range
B.flash point
C.ignition temperature
D.combustion temperature
A.the pressure regulating valve is not closing
B.an excessive lack of refrigerant in the system
C.badly leaking discharge valves
D.worn piston rings
A.Both are higher than normal burning temperatures
B.The flash point is always higher
C.The ignition temperature is always higher
D.They are not necessarily related
A.tend to twist about its long axis
B.expand in length and in diameter
C.contract in length and expand in diameter
D.flex at right angles to the applied pressure
A.holding the discharge valve open
B.relieving the intercooler pressure to the atmosphere
C.using an enlarged, permanently opened clearance expansion space
D.a pre-charged accumulator
最新试题
A salinity indicator is used to determine the ().
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should ().
A salinity indicator is used to determine the ().
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?()
The general purpose of a heat exchanger is to ().
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?()
An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will ().
Which of the following statements is correct concerning heat transfer?()
Which of the listed pumps is NOT a positive displacement pump?()