單項(xiàng)選擇題Some chloronated flourocarbon refrigerants may decompose into a toxic irritating gas if it is （）.

A.stored at temperatures below 60 degrees Fahrenheit
B.charged into a system having copper fittings
C.allowed to mix with compressor oil
D.exposed to an open flame or hot surface


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1.單項(xiàng)選擇題A refrigeration system contaminated with moisture can be affected by （）.

A.acid formation
B.sludge formation
C.ice in the expansion valve
D.All of the above

2.單項(xiàng)選擇題R-12 is generally considered to be a safe, nontoxic, nonflammable, and non-explosive refrigerantIt can, however, become highly toxic when （）.

A.superheated outside the system
B.in contact with an open flame
C.heated to the boiling point
D.All of the above

3.單項(xiàng)選擇題Which of the following statements is/are true regarding hydraulic pumps in general? （）

A.Variable volumes can be obtained with gear pumps only by variation of the pump drive speed
B.A radial piston pump houses sliding pistons in a stationary cylinder block through which passes a rotating pintle or ported shaft
C.The amount of fluid displaced per revolution of an axial piston rotary pump is dependent on the angle formed between the cylinder block and valve plate
D.All of the above

4.單項(xiàng)選擇題The function of the hydraulic telemotor transmitter used in an electro-hydraulic steering gear system is to （）.

A.transmit the rudder angle to the bridge indicator
B.prevent the control linkage from striking the stops when hard over
C.automatically purge all entrained air from the system
D.send hydraulic signals to the receiving unit

5.單項(xiàng)選擇題To obtain maximum efficiency, two stage air compressors are usually （）.

A.horizontally mounted
B.never fitted with intake filters
C.fitted with intercoolers
D.operated in an unloaded condition at all times