If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably _____.A.misalignment or worn main bearingsB.insufficient cylinder lubricationC.defective or poorly fitted valvesD.All of the above
If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably _____.
A.misalignment or worn main bearings
B.insufficient cylinder lubrication
C.defective or poorly fitted valves
D.All of the above
相关考题：
In a chilled(冷的) water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by ______.A.increasing refrigerant pressure in the coilB.increasing chilled water flow through the coolerC.sub-cooling the refrigerant in the condenserD.superheating the refrigerant in the compressor
Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of ______.A.refrigerant bubbles in the lube oilB.refrigerant reducing the lube oil viscosityC.oxidation(氧化) of the lube oil from overheatingD.reducing the floc or cloud point of the oil
Sludge may form in the crankcase of an air conditioning compressor as a result of ______.A.bubbling refrigerantB.overheating and oxidationC.lowered operating temperaturesD.reducing the cloud or floc point
What is the most probable cause of reduced capacity in a reciprocating air compressor ________．A.Carbon on cylinder headsB.Faulty unloaderC.Leaking air valvesD.Plugged air cooler
单选题Excessive lube oil consumption by a reciprocating air compressor can be caused by （）.Ausing a slightly dirty air filterBusing oil having an excessive viscosityCintercooler or after-cooler leaksDcarrying the oil level higher than normal
单选题The sudden reduction of pressure occurring within the crankcase of a refrigeration compressor during starting causes the （）.Asudden evaporation of wax crystals in the lubricantBsudden evaporation of entrapped air in the lubricantCrelease of refrigerant from the oil/refrigerant mixtureDrelease of dissolved lubricant from the refrigerant
单选题Air blowing from the intake air filter of an operating air compressor indicates （）.Abroken inlet valvesBbroken discharge valvesCpulsations in the air distribution systemDoverloading of the air distribution system
单选题Air France carries out its Frequency Plus _____.Athrough its reduced ticket pricesBthrough its extensive network of partnersCby providing convenient flight schedulesDby offering excellent services on board
单选题The unloading system on an air compressor will （）.Aincrease compressor discharge pressure on demandBincrease compressor operating speed as necessaryCallow the motor to turn the compressor opposed only by frictionDreduce the compressor frictional load when starting
单选题In an air conditioning system, low head pressure associated with a reciprocating compressor can be the result of （）Abroken valve springsBtight drive beltsChigh line voltageDair in the system
单选题Sludge may form in the crankcase of an air conditioning compressor as a result of （）.Abubbling refrigerantBoverheating and oxidationClowered operating temperaturesDreducing the cloud or flash point
单选题The knock occurring when a cold diesel engine is started and continues while running at low speed, but stops when the engine reaches normal operating speed and temperature, is（）.Acaused by retarded injection timingBcaused by a mechanical defect in one cylinderCcaused by high fuel injection pressuresDnormal for these conditions
单选题（）are supplied by main switchboard directly.ASuez Canal searchlight, air compressor and air conditioning compressorBAir compressor, boiler blower and refrigeration plantCBoiler blower, Suez Canal searchlight and refrigeration plantDSuez canal searchlight, air compressor and boiler blower
单选题The compressed air is admitted to each cylinder through a cam operated by starting air valve when the piston has just passed its （）.ABDCBTDCCBBDCDATDC
单选题Broken valve strips in an operating low pressure, air compressor will cause （）.Aan immediate crankcase explosionBoil contamination in the compressed airCa decrease in compressor capacityDno immediate loss of the compressed air capacity
单选题Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?（）AThe density of the air entering the compressorBThe temperature of the air entering the compressorCThe designed rotating speed of the compressorDA leaking head gasket
单选题In a chilled water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by （）.Aincreasing refrigerant pressure in the coilBincreasing chilled water flow through the coolerCsub-cooling the refrigerant in the condenserDsuperheating the refrigerant in the compressor
单选题A knocking sound from one cylinder of an operating air compressor indicates （）.Aa defective or broken high pressure un-loaderBa loose valve plateCexcessive overloadDno compression
单选题A reciprocating air compressor is running roughly and vibrating excessively, indicating that the （）.Acompressor is overloadedBmotor is overloadedCfoundation bolts are looseDbelts are too tight
单选题If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably （）.Amisalignment or worn main bearingsBinsufficient cylinder lubricationCdefective or poorly fitted valvesDall of the above
单选题Sludge may form in the lubricating oil crankcase of a reciprocating air conditioning compressor as a result of （）.Awax precipitation in the lube oilBcontamination by dust, scale, or moistureCrefrigerant bubbles in the lube oilDrefrigerant reducing the lube oil viscosity
单选题Late fuel injection occurring at, or after TDC in a diesel engine is indicated by excessive exhaust smoke and （）Alow exhaust temperatureBlow firing pressureCfuel knock in each cylinderDmechanical knock in each cylinder
单选题Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of （）Arefrigerant bubbles in the lube oilBrefrigerant reducing the lube oil viscosityCoxidation of the lube oil from overheatingDreducing the floc or cloud point of the oil
单选题When the starting air valve closes on one cylinder, another starting air valve has （） opened on another cylinder whose piston has just commenced its downward stroke.AjustBnearlyCmerelyDalready
单选题Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by（）.Aleaky discharge valves on the LP cylinderBleaky discharge valves on the HP cylinderCinsufficient intercooler coolingDlow ambient air pressure
单选题Which of the following problems would be the probable cause for the faulty operation of a reciprocating air compressor suction valve?（）ACarbon build up in the piston ring beltBFaulty operation of a cylinder un-loaderCCompressor operation in an area of high relative humidityDLifting of intercooler rebel valve