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
Sludge may form in the lubricating oil crankcase of a reciprocating air conditioning compressor as a result of （）.
A
wax precipitation in the lube oil
B
contamination by dust, scale, or moisture
C
refrigerant bubbles in the lube oil
D
refrigerant reducing the lube oil viscosity
参考解析
解析：
暂无解析
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
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
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
Which lubricating oil additive is used in diesel engines to reduce the tendency(倾向)for sludge and varnish to form on the engine parts?A.Flash point improversB.Pour point improversC.InhibitorsD.Foam suppressors(抑制物)
单选题（） that everything in the engine crankcase is correct, start up the crankcase lubricating oil pump.ATo satisfyBTo be satisfiedCAfter satisfyingDAfter being satisfied
单选题Black smoke exhausting from an operating diesel engine is an indication of poor combustion which may be caused by （）Awater in the fuelBinsufficient fuel for combustionCclogged air intake passagesDburning lubricating oil
单选题One characteristic of a lubricating oil adversely affecting the result of centrifuging is （）Ahigh TBN valueBlow oil floc pointClow oil demulsibilityDlow oil neutralization number
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Excessive lubricating oil consumption in a running diesel engine can be caused by （）Aclogged lube oil pipingBexcessive valve-guide clearanceChigh lube oil viscosityDlow lube oil temperature
单选题Which of the following conditions is most likely to occur when unburned fuel contaminates the crankcase of a diesel engine?（）ALube oil is diluted and its viscosity is reducedBSulfuric acid is formedCBearings become pitted ad immediately failDValve stems develop sludge deposits
单选题In a refrigeration system, foaming of the crankcase oil may cause the （）.Aexpansion valve to overfeedBcompressor to knockCwater regulating valve to failDcrankcase drains to plug
单选题What function is provided by the crankcase ventilation system on some diesel engines?（）AIncreases the sludge forming tendency of lube oilBPrevents the accumulation of combustible gasesCImproves lube oil coolingDImproves cold weather starting
单选题Under normal conditions, the main source of crankcase oil contamination is attributed to （）Ametal particles loosened by wearBair when air cleaners are not usedCcondensation of water vaporsDbreakdown of the lubricating oil by dilution
单选题In a disk-type lubricating oil purifier, （）Athe purifier driving gears are lubricated by the reclaimedBoil as it leaves the bowl all dirt and sludge are automatically discharged with the cooling waterCsealing water must never be supplied until after oil is fed to the unitDdeterioration of the bowl ring gasket will cause the purifier to lose its water seal
单选题What is one effect of running a diesel engine at too cool a temperature? （）ABuildup of sludge in the lubricating systemBExcessive fuel consumptionCSevere heat stresses on mechanical partsDFoaming of the lubricating oil
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In engines with system, the lubricating oil can be added to the engine through the filling hole in the crankcase cover, by using a hand oil can, or through the separator pipe（）Alubricating oilBdry sumpCcirculated tankDwet sump
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When fuel enters the crankcase of a diesel engine, it （）Adilutes the lube oil and reduces its viscosityBforms sulfuric acid in the lube oilCcauses pitting and failure of the bearingsDcauses sludge deposits on valve stems
单选题Lubricating oil viscosity in an operating diesel engine can be reduced by（）Aincreasing cooling water flowBincreasing lube oil flowCdilution by fuel oilDadding SAE 70 oil
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Lubricating oil systems for diesel engine journal bearings are usually lubricated by which of the following types of lubricating oil systems?（）ASplashBGravityCPressureDBypass
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Which lubricating oil additive is used in diesel engines to reduce the tendency for sludge and varnish to form on the engine parts?（）AFlash point improversBPour point improversCInhibitorsDFoam suppressors