A . remove suspended and precipitated solids from the boiler water
B . completely drain the boiler in an emergency situation
C . prevent hardened scale deposits in the water drum
D . remove floating impurities from the oily water surface
[单选题]Temperature control valves installed in the jacket cooling water system of a diesel engine modulates the rate of water flow through the ().A . cooling water pumpB . nozzle cooling passagesC . cylinder jacketsD . heat exchanger
[单选题]Blow-off of the relief valves of the main cylinders during operation indicates ().A . the cylinder cover is crackedB . the injector holes is cloggedC . the cams are not properly setD . fuel pump is leaking
[单选题]The correct procedure for giving an auxiliary boiler a bottom blow, is to begin .A.when the boiler has been secured long enough for most solids to settleB.when the boiler has been cooled to ambient temperatureC.only after raising the water level to w
[单选题]D.iesel engine blow-by is the leakage of combustion gases past the( ).A.oil rings onlyB.compression and scraper ringsC.cylinder liner sealingD.cylinder liner ring grooves
[试题]A.ftertherobbery,theshopinstalledasophisticatesalarmsystemasaninsurance_________furtherlosses.A.)forB)fromC.)againstD)towards
[单选题]A. new Ezonexam switch is installed into an existing LAN and a new VTP trunk is set up with an existing switch. Which VLANs will be allowed on this new trunk?A.All defined VLANs are allowed on the trunk by default.B.Each VLAN, or VLAN range, that is
[单选题]Fins are installed on the generating tube surfaces in waste heat boilers to ().A . prevent soot fires in the exhaust systemB . prevent exhaust gas erosion of the tubesC . increase the velocity of exhaust gas flowD . increase the rate of heat transfer
[单选题]The intake valves in a diesel engine are reseated by ().A . cam followersB . push rodsC . combustion gasesD . valve spring
[单选题]The purpose of the safety relief valves installed on an auxiliary boiler is to ().A . relieve excess fuel oil pressure during the “off” fire cycleB . admit water to the dry pipeC . throttle the forced draft fan output for proper combustio
[单选题]F.usible plugs are installed in fire-tube boilers to _____.A.provide a means of draining the boilerB.warn the engineer of low water levelC.cool the crown sheet at high firing ratesD.open the burners electrical firing circuits