A compressor should never be stopped （）.
A、without first cooling it
B、without first heating it
C、without first unloading it
D、without first loading it
相似题目
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A non-return valve in the air delivery line near to the compressor must be （）type similar to the compressor discharge valve.
A、the low inertia
B、the high inertia
C、the low velocity
D、the high velocity
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If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
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
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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
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When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
A . increase the amount of cooling water to the condenser
B . decrease the amount of cooling water to the condenser
C . add more refrigerant to the system
D . remove some refrigerant from the system
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If a refrigeration compressor will not start, the reason may be （）.
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 ring
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The crankcase cover should never be allowed to open for investigation when （）
A . the engine stops
B . the engine is running
C . you repair the engine
D . overhauling the engine
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If a refrigeration compressor is short cycling on high head pressure, you should （）.
A . purge the condenser if the waterside is dirty
B . check for proper water flow through the condenser
C . increase the high pressure cutout setting
D . reduce the cooling water flow
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A warmer than normal compressor suction line might be caused by （）.
A . insufficient lubrication
B . insufficient refrigerant
C . excess refrigerant
D . excessive opening of the expansion valve
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If a compressor runs continuously, the cause might be a（）
A . defective thermal bulb
B . clogged scale trap
C . stuck high-pressure switch
D . stuck low-pressure switch
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Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）
A . Sub-cooled liquid
B . Sub-cooled vapor
C . Superheated vapor
D . Liquid
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If a large difference exists between the compressor discharge pressure and the pressure corresponding to the existing condensing temperature in a refrigeration system, you should（）.
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 dirty intercooler on the ship service air compressor will result in （）.
A . decreased compression ratio
B . higher than normal power consumption
C . un-loader malfunction
D . water in the lubricating oil
-
Noise in a refrigeration compressor can be caused by （）.
A . worn bearings and piston pins
B . slugging due to flooding back
C . too much oil in circulation
D . All of the above
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Before starting an air compressor, It should be （）.
A . unloaded
B . primed
C . filled with water
D . greased
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A centrifugal compressor’s purge recovery unit（）
A . reclaims water
B . purges air without losing refrigerant
C . purges air with some loss of refrigerant
D . purges lube oil from the refrigerant
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When a DHCP server is configured, which two IP addresses should never be assignable to hosts?（）
A . network or subnetwork IP address
B . broadcast address on the network
C . IP address leased to the LAN
D . IP address used by the interfaces
E . manually assigned address to the clients
F . designated IP address to the DHCP server
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If you want to listen well, you should listen to lots of new materials, and never stick on to one piece of material.
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When upgrading the room, we should never pay the extra charge.
-
The room attendant should never touch the banknotes or documents on the desk when cleaning the guestroom.
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We should never ourselves to danger.
-
Architects should never copy others’ architectural designs.
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(8) Computers should never have been invented.To what extent do you agree or disagree with this statement?
-
We should never underestimate influence we can have on the children we love.
A．undersell
B．undervalue
C．disregard
D．misjudge
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They should never try to pursue profit health and life of people.
A、in terms of
B、at sight of
C、at the expense of
