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

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• CO2 cylinders equipped with pressure actuated discharge heads will discharge automatically when（）.

  A . the discharge valve is open B . the control box glass is broken C . pressure from the control cylinders is detected D . the control cylinders have been completely discharged

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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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• 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 pressure head of a pump is given in the unit of （）.

  A . kg B . MPa C . meter fluid column D . None of the above is true

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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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• The pressure difference of the gauge on the oily water separator increases greatly, the reason is（）

  A . the filter is clogged B . bilge suction value is clogged C . suction value and discharge value of the pump do not open fully D . screw pump is worn seriously and volumetric efficiency is decreased

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• One cause of high head pressure occurring in a refrigeration system can be （）.

  A . insufficient cooling water flow to the condenser B . a low refrigerant charge in the system C . the liquid valve is open too much D . high evaporator superheat

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• In order to withstand fluid head pressure on a ship，stiffeners are often attached to the bulkhead（）.

  A . penetrations B . plating C . framing D . bracket

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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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• 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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• The volute of centrifugal pump also acts as a diffuser converting （）into pressure head.

  A . mechanical energy B . heat energy C . potential energy D . kinetic head

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• Charging-air pressure increases if there is incorrect combustion and drop in the （） of the diesel engine.

  A . machine efficiency B . machinery efficiency C . mechanical efficiency D . mechanics efficiency

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• Low compressor head pressure in a refrigeration system can be caused by（）.

  A . insufficient condenser cooling water B . excessive condenser cooling water C . air in the refrigeration system D . excessive refrigerant in the system

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• The pressure head of a water pump is given in the unit of （）.

  A . kg B . MPa C . mH20 D . None of the above

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• An increased pressure differential between the inlet and outlet of a strainer usually indicates the strainer is （）

  A . holed B . fouled C . clean D . dry

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• （） provides the head or pressure to supply the domestic water where required.

  A . The compressed air B . The compressing air C . The transfer pump D . The head tank

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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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• Daniel held her head up so she could breathe and _______pressure to her wounds.

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• 末段终点流量增大时，末段起、终点压力都要减小。相反，终点流量减小时，末段起、终点压力都要增大。When the terminal flow increases, the terminal pressure should be reduced. On the contrary, when the terminal flow decreases, the terminal pressure increases.

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• Why does an increase in price cause an increase in supply（）

  A．Consumers buy more goods when prices are high B．Producers want to sell all of their goods C．Producers make more goods when prices are high D．Consumers will not buy all of the goods

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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 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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• 气体的粘度随压力增高而增高。在低压时，气体粘度随温度升高而增加，随着压力的增加，温度升高对粘度增大的影响越来越小，当压力很高时（100×105Pa以上），气体粘度随温度升高而降低，明显表现出类似于液体的性质。Table 1-13 shows the dynamic viscosity of methane at different pressures and temperatures. It can be seen from the table that the viscosity of gas increases with the increase of pressure. At low pressure, the gas viscosity increases with the increase of temperature. With the increase of pressure, the influence of temperature increase on the inc

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