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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
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更多 “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 oilB contamination by dust, scale, or moistureC refrigerant bubbles in the lube oilD refrigerant reducing the lube oil viscosity” 相关考题
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
考题
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
考题
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
考题
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
考题
The ______is used to burn oil sludge.A.clarifierB.oily water separatorC.incineratorD.distiller
考题
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)
考题
单选题（） that everything in the engine crankcase is correct, start up the crankcase lubricating oil pump.A
To satisfyB
To be satisfiedC
After satisfyingD
After being satisfied
考题
单选题Black smoke exhausting from an operating diesel engine is an indication of poor combustion which may be caused by （）A
water in the fuelB
insufficient fuel for combustionC
clogged air intake passagesD
burning lubricating oil
考题
单选题One characteristic of a lubricating oil adversely affecting the result of centrifuging is （）A
high TBN valueB
low oil floc pointC
low oil demulsibilityD
low oil neutralization number
考题
单选题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 flash point
考题
单选题Excessive lubricating oil consumption in a running diesel engine can be caused by （）A
clogged lube oil pipingB
excessive valve-guide clearanceC
high lube oil viscosityD
low lube oil temperature
考题
单选题Which of the following conditions is most likely to occur when unburned fuel contaminates the crankcase of a diesel engine?（）A
Lube oil is diluted and its viscosity is reducedB
Sulfuric acid is formedC
Bearings become pitted ad immediately failD
Valve stems develop sludge deposits
考题
单选题In a refrigeration system, foaming of the crankcase oil may cause the （）.A
expansion valve to overfeedB
compressor to knockC
water regulating valve to failD
crankcase drains to plug
考题
单选题What function is provided by the crankcase ventilation system on some diesel engines?（）A
Increases the sludge forming tendency of lube oilB
Prevents the accumulation of combustible gasesC
Improves lube oil coolingD
Improves cold weather starting
考题
单选题Under normal conditions, the main source of crankcase oil contamination is attributed to （）A
metal particles loosened by wearB
air when air cleaners are not usedC
condensation of water vaporsD
breakdown of the lubricating oil by dilution
考题
单选题In a disk-type lubricating oil purifier, （）A
the purifier driving gears are lubricated by the reclaimedB
oil as it leaves the bowl all dirt and sludge are automatically discharged with the cooling waterC
sealing water must never be supplied until after oil is fed to the unitD
deterioration of the bowl ring gasket will cause the purifier to lose its water seal
考题
单选题What is one effect of running a diesel engine at too cool a temperature? （）A
Buildup of sludge in the lubricating systemB
Excessive fuel consumptionC
Severe heat stresses on mechanical partsD
Foaming of the lubricating oil
考题
单选题Crankcase explosions in propulsion diesel 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
考题
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（）A
lubricating oilB
dry sumpC
circulated tankD
wet sump
考题
单选题In a normally operating diesel engine, the main cause of lubricating oil contamination in the crankcase is a result of the （）.A
metal particles loosened by wearB
air when no air cleaners are usedC
condensation of water vaporsD
breakdown of the lubricating oil by dilution
考题
单选题The （）is used to burn oil sludge.A
clarifierB
oil/water separatorC
incineratorD
distiller
考题
单选题When fuel enters the crankcase of a diesel engine, it （）A
dilutes the lube oil and reduces its viscosityB
forms sulfuric acid in the lube oilC
causes pitting and failure of the bearingsD
causes sludge deposits on valve stems
考题
单选题Lubricating oil viscosity in an operating diesel engine can be reduced by（）A
increasing cooling water flowB
increasing lube oil flowC
dilution by fuel oilD
adding SAE 70 oil
考题
单选题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 of the lube oil from overheatingD
reducing the floc or cloud point of the oil
考题
单选题Lubricating oil systems for diesel engine journal bearings are usually lubricated by which of the following types of lubricating oil systems?（）A
SplashB
GravityC
PressureD
Bypass
考题
单选题Which harmful consequence may be the result of lube oil sludge accumulation? （）A
Clogged oil pump suction screensB
Increased oil operating temperaturesC
Sticking piston ringsD
All of the above
考题
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?（）A
Flash point improversB
Pour point improversC
InhibitorsD
Foam suppressors
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