A.only by the pump as its primary function
B.by resistance to the fluid flow through the system
C.by the thermal input to the systems fluid
D.solely by the charge applied by the accumulators
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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
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
最新试题
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?()
Which of the listed pumps is NOT a positive displacement pump?()
One cause of high head pressure occurring in a refrigeration system can be ().
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?()
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of ().
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is ().
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?()
An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().
Low compressor head pressure in a refrigeration system can be caused by().
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump ().