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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 oil
B.refrigerant reducing the lube oil viscosity
C.oxidation(氧化) of the lube oil from overheating
D.reducing the floc or cloud point of the oil
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更多 “ 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 ” 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
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What is the most usual reason for the fresh water-sea water heat exchanger fouling in the sea side?A.lube oil sludge accumulating in itB.dirt and scale etc , formed on the surfacesC.deformation of the tubes and the shell or the platesD.lube oil leakage into sea-water side
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
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
单选题Excessive lube oil consumption by a reciprocating air compressor can be caused by （）.A
using a slightly dirty air filterB
using oil having an excessive viscosityC
intercooler or after-cooler leaksD
carrying the oil level higher than normal
考题
单选题A dirty intercooler on an air compressor will cause （）.A
damage to the un-loader operating diaphragmB
an increase in current flow to the motorC
high pressure in the receiver and filterD
an excessive consumption of crankcase oil
考题
单选题An increase in diesel engine crankcase pressure generally indicates excessive（）A
compression pressureB
lube oil header pressureC
scavenge air pressureD
piston ring blow-by
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单选题If plastic film insulation becomes damaged in air conditioning system, （） may form within the film.A
evaporationB
condensationC
liquefiesD
vaporization
考题
单选题In an air conditioning system, low head pressure associated with a reciprocating compressor can be the result of （）A
broken valve springsB
tight drive beltsC
high line voltageD
air in the system
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In general, the oil mist defectors include a base plate with air blast pumpThe function of air blast pump is to （）crankcase.A
supply clean air to the measuring compartment of the units for more accuracyB
generaate the pressure required for the extraction of the oil mist from theC
generate the pressure required for the extraction of the oil mist from the crankcaseD
supply clean air to the measuring track of the units for more accuracy
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Mist detectors used on large low-speed main propulsion diesel engines monitor and check for the presence of （）.A
fuel oil vapor at the sludge tank ventB
unburned fuel vapors in the scavenge air receiverC
lube oil vapors in the crank caseD
lube oil vapors in the engine room
考题
单选题Regarding a Diesel engine crankcase, the general arrangement and installation should preclude the possibility of （）A
free entry of air to the crankcaseB
water entering the crankcase while engine wash-downs are being performedC
excessive oil leakage during periods of increased blow-byD
sub-cooling internal components
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 chilled 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
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The accumulation of air and other non-condensable gases in a refrigeration system will （）.A
cause a loss of the liquid sealB
create a vapor lock in the liquid receiverC
collect in the condenserD
cause foaming of the oil in the crankcase
考题
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
考题
单选题How dose water enter the crankcase of a diesel engine?（）A
Through the crankcase exhausterB
As water vapor contained in blow-byC
Demulsifying lube oil passing through the main bearingsD
Condensation from vapor formed in the expansion tank
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
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