The pressure in an operating diesel engine cylinder continues to rise for a short period after the piston passes top dead center as a result of the （）

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• （） are used to limit the pressure in any particular portion and mainly control the pressure after the valve.

  A、Relief valves B、Safety valves C、Check valves D、Reducing valves

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• A substantial increase in crankcase pressure could be an indication of （）

  A . excessive lube oil pressure B . the proper seating of new rings C . a worn cylinder liner D . a malfunctioning cylinder relief valve

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• The （） is a crystal which, under pressure, produces an electric current which varies with the pressure.

  A . alternator B . glass thermometer C . burdon tube D . piezoelectric pressure transducer

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• In an oil cooler circulated by sea water, the oil is at a larger pressure the result being that any leak in the cooler will mean a loss of （）.

  A . oil B . sea water C . refrigerant D . fresh water

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• The compressor in an air-cooled condensing refrigeration system is short cycling on the high pressure cutout switch（）

  A . system is overcharged with refrigerant B . system is low on refrigerant C . discharge valves are leaking excessively D . discharge valves are leaking slightly

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• A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.

  A . the four-way control valve failing to shift B . the bleeder valve sticking in the open position C . cold hydraulic fluid D . a clogged air vent falter on the oil reservoir

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• The high air velocity leaving the compressor of an exhaust gas turbocharger is converted to pressure in the （）

  A . inlet nozzle ring B . turbine wheel blade C . diffuser passages D . inlet vol

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• In an auxiliary boiler steam and water system, the highest pressure will be in the （）.

  A . steam stop valve B . dry pipe C . feedwater system D . generating tube

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• In the Northern Hemisphere，an area of counterclockwise wind circulation surrounded by higher pressure is a（）.

  A . low B . high C . warm front D . cold front

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• In a compression refrigeration plant the refrigerant is under low pressure in the （） and under high pressure in the （）.

  A . compressor；condenser B . condenser；evaporator C . throttle valve；evaporator D . evaporator；condenser

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• High exhaust back pressure will result in an increase in （）

  A . turbocharger efficiency B . engine power output C . carbon deposits on fuel injectors D . cylinder scavenging

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• An axial piston, variable stroke pump is used in a vessels hydraulic steering gearUnder pressure, oil continually leaks out from between the valve plate/cylinder barrel and will（）.

  A . cause loss of hydraulic oil from the system B . result in extreme damage to the pump C . cause damage to the pump ff not continually drained from the pump casing D . result in the system high side pressure to substantially drop off

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• （） the supercharge pressure is, （） power an engine develops.

  A . The higher；the more B . Higher；more C . Higher；little D . The higher；the le

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• The vapor pressure of a gas is the pressure necessary to keep it in a(n)（）.

  A . soluble state B . solid state C . liquefied state D . inert state

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• Broken valve strips in an operating low pressure, air compressor will cause （）.

  A、an immediate crankcase explosion B、oil contamination in the compressed air C、a decrease in compressor capacity D、no immediate loss of the compressed air capacity

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• An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.

  A . restriction in refrigerant piping B . air and non-condensable gases in the condenser C . water in the refrigerant D . flooding back of liquid refrigerant from the evaporator

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• Which operation may cause the pressure in an inert tank to fall below the prescribed limits（）.

  A . Loading B . Discharging C . Crude oil washing D . Steaming tank

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• According to Buys Ballot’s law，when an observer in the Northern Hemisphere experiences a northwest wind，the center of low pressure is located to the（）.

  A . northeast B . west-southwest C . northwest D . south-southeast

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• If an observer in the Northern Hemisphere faces the surface wind，the center of low pressure is to his（）.

  A . left，slightly behind him B . right，slightly behind him C . left，slightly in front of him D . right，slightly in front of him

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• As for an oil-fired boiler if at a normal steaming condition and water goes out of sight in gauge glasses the action you should take is: （） (1) secure oil to fires (2) increase feed pump pressure

  A . （1） B . （1）and（2） C . （2） D . neither（1）nor（2）

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• As for an oil-fired boiler if at a normal steaming condition and water goes out of sight in gauge glasses the action you should take is: (1) secure oil to fires; (2) increase feed pump pressure.

  A.(1) B.(1) and (2) C.(2) D.neither (1) nor (2)

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• The pressure range between the system cut in and cut out pressures in a refrigeration unit is known as_______.

  A.opposing operational drag B.pressure distribution C.differential D.system purge

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• The equation shows that the slope of a plot of chemical potential against pressure is equal to the molar volume of the substance. An increase in pressure raises the chemical potential of any pure subs

  A．To raise the melting temperature slightly． B．To lower the melting temperature slightly． C．Negligibl E．No effect at all． D．None the above

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• Which of the following would lead to an increase in the vapor pressure of a liquid I. Increasing the temperature II. Adding a nonvolatile

  A．I only B．II only C．Both I and II D．Neither I nor II

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