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
Sludge may form in the crankcase of an air conditioning compressor as a result of ______.
A.bubbling refrigerant
B.overheating and oxidation
C.lowered operating temperatures
D.reducing the cloud or floc point
相关考题：
Crankcase explosions in propulsion diesel engines result from ____.A.the splashing of lubrication oil by the crankshaftB.the dilution of crankcase oil with particles of combustionC.broken fuel lines spraying oil on the crankcaseD.the ignition of unburned fuel and air in the crankcase
If the refrigeration compressor crankcase is sweating, the cause may be due toA.a shortage of refrigerantB.the compressor running continuouslyC.liquid refrigerant returning to the compressorD.the compressor short cycling on the high pressure cutout
第二组Under normal operation, some lubrication oil mist may be discharged from the air compressor to the air start system. This oil may be from excess compressor cylinder lubrication, from faulty oil scraper rings, or may even be suspended oil vapor contaminating the engine room atmosphere and drawn in at the compressor suction. Oil discharge is kept to a minimum by draining the after cooler, air receiver and starting system. If small quantities of lubrication oil do get passed into the starting air system, they will deposit as thin moist film over internal pipe surfaces but are not readily combustible. If a cylinder non-return valve leak while the engine is in operation, some hot gas, possibly with unburned fuel and cylinder lubrication oil, may be blown through the valve to the adjacent air manifold. With further heating from the leaky valve, this, together with the already deposited oil film, will carbonize and form. incandescent carbon. If starting air is applied to the system while still hot, the high pressure air coming into contact with the burning carbon may cause an explosion. Such an explosion will cause a flame to pass back through the air start pipe system, evaporating the deposited oil film and igniting it in the presence of air. Very high velocities and shockwaves are generated which may rupture pipes and fittings.Alternatively, if excessive oil has entered the air start system, a mixture of air and oil droplets may be discharged through the open cylinder non-return valve during starting. This spray may ignite due to high temperatures in the cylinder, causing a flame through the still open valve to the air manifold.To prevent an explosion, air start valves must be correctly maintained and lubricated to ensure correct timing and free movement with positive closing. Oil in the system must be kept to a minimum, pipe lines must be drained and cleaned internally when necessary and oil discharge from air compressors must be kept to a minimum by good maintenance.The passage is mainly aboutA.crankcase explosionB.scavenge box fireC.starting air pipeD.the danger of explosion in the starting air system
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
单选题A dirty intercooler on an air compressor will cause （）.Adamage to the un-loader operating diaphragmBan increase in current flow to the motorChigh pressure in the receiver and filterDan excessive consumption of crankcase oil
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If plastic film insulation becomes damaged in air conditioning system, （） may form within the film.AevaporationBcondensationCliquefiesDvaporization
单选题Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.Aoverheated compressor bearingsBexcess lube oil viscosityCcarbon deposits on the compressor piston ringsDwax crystals forming in the lubricant
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Insufficient refrigerant in a refrigeration plant may result in （）.Ahigh discharge pressureBfrosting of the crankcaseChigh temperature of the overboard waterDlow suction pressure of compressor
单选题Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to （）.Amaintain adequate coil back pressureBprohibit flashing in the liquid lineCreduce refrigerant volume in the systemDreduce compressor discharge line loading
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If the electric motor driving an air compressor fails to start, the cause may be a （）.Aleaking unloaderBtripped circuit breakerCcontrol line leakDdefective pop valve
单选题If the refrigeration compressor crankcase is sweating, the cause may be due to （）.Aa shortage of refrigerantBthe compressor running continuouslyCliquid refrigerant returning to the compressorDthe compressor short cycling on the high pressure cutout
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Crankcase explosions in propulsion diesel result from（）Athe splashing of lubrication oil by the crankshaftBthe dilution of crankcase oil with particles of combustionCbroken fuel lines spraying oil on the crankcaseDthe ignition of unburned fuel and air in the crankcase
单选题A dirty intercooler on the ship service air compressor will result in （）.Adecreased compression ratioBhigher than normal power consumptionCun-loader malfunctionDwater in the lubricating oil
单选题Starting air for auxiliary engines may be taken directly from the main reservoirs or through （）.Aan auxiliary reservoirBa controlling air bottleCan emergency air compressorDa main air compressor
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To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, you should （）Aadmit only enough fresh outside air to provide proper ventilationBreduce the air reheating system loadClower the compressor head pressureDoperate the purge recovery unit continuously
单选题In a normally operating diesel engine, the main cause of lubricating oil contamination in the crankcase is a result of the （）.Ametal particles loosened by wearBair when no air cleaners are usedCcondensation of water vaporsDbreakdown of the lubricating oil by dilution
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Which harmful consequence may be the result of lube oil sludge accumulation? （）AClogged oil pump suction screensBIncreased oil operating temperaturesCSticking piston ringsDAll of the above
单选题Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include （）Achanging the air filterBrecharging the systemCchanging compressor lubricantDrenewing container vacuum