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16 Cards in this Set
- Front
- Back
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A float operated low-water fuel cutoff has its switch separated from boiler pressure by
a) a float cage b) a mercury envelope c) a flexible diaphragm d) a siphon e) packing |
C
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A mercury switch bulb is under high vacuum and contains inert gas a) so it will not explode b) to prevent corrosion of the contacts c) to decrease electrical resistance d) so contacts will not overheat e) because the switch is normally closed |
B
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A float operated level control a) will recognize swell and shrinkage and correct the feedwater flow b) will have the float in the boiler drum c) is only used on small boilers d) is used on firetube boilers only e) must be used when a boiler is manually operated |
C
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Overheating of boiler heating surfaces due to low water a) is the main cause of boiler failure b) will cause a furnace explosion c) can be eliminated with a low-water fuel cutoff d) cannot occur if the boiler is a hot water unit e) can be prevented with proper water treatment |
A
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A low water fuel cut-off is fitted to a boiler to prevent a) damage to the radial stays in the steam dome b) the fire from shutting off too quickly and damaging the boiler c) shutting off the water when there is no fuel d) damage to the boiler from an overheated condition e) damage to the boiler from over pressure |
D
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The purpose of a low water fuel cut-off is to a) shut off the feedpump when the water level gets too high b) shut off the fuel supply when the burner flame goes out c) shut off the fuel supply when the water pressure is too low d) start the stand-by feedwater pump when level is low e) shut off the fuel supply when the water level gets too low |
E
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A low water fuel cut-off may be activated by a) lowering the water level in the boiler b) lowering the water level with the try cocks c) lowering the water level in the gage siphon d) lowering the water with the surface blowdown e) lowering the water level in the sight glass |
A
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The CSA code states that a boiler not under continuous attendance must be equipped with a low-water fuel cutoff which a) must be a normally open switch b) can also activate an alarm c) may be equipped with isolation valves d) must be a manually reset device e) serves no other purpose |
E
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A low-water fuel cutoff which serves no other purpose a) cannot be equipped with isolation valves b) must be a normally closed switch c) must be a manually reset switch d) must be a float activated switch e) cannot be an electrical conducting type |
A
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A low-water fuel cutoff switch should close the automatic fuel valve(s) when the water level is a) at the lowest permissible water line b) at the lowest visible water line c) 1 to 2.5 cm above the bottom gage glass nut d) 1 to 2.5 cm below the gage glass nut e) 76 mm above the lowest permissible water line |
C
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A hot water boiler low-water fuel cutoff a) should be tested weekly during routine boiler operation b) cannot be tested during routine boiler operation c) cannot be tested d) should be located on the expansion tank e) must have a normally closed switch |
B
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The drain of a hot water boiler low-water fuel cutoff should be opened to flush out any debris a) annually b) daily c) weekly d) monthly e) each shift |
C
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To test a low water fuel cut-off a) call for an electrician who specializes in boiler controls b) lower the water level until the burner shuts down c) connect an ammeter to the mercury switch d) test the water column with a test gage e) shut off the fuel to the boiler |
B
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The float chamber of the low water cut-off is blown out often to prevent a) the chamber collecting sediment b) the electric wiring from deteriorating c) the mercury from oxidizing d) the magnets rusting e) water hammer to the chamber |
A
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The most reliable method of checking or testing a low-water fuel cut off is to a) manually trip the cut-off linkage to shut off the burner b) blow the float chamber down to see if the burner will cut out c) lower the water in the boiler to the level where the burner should cut out d) blow the low water cut-off down through the water column until the burner cuts out e) blow down the sight glass to see if the burner goes out |
C
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The low water cut-off can be tested by a) raising steam pressure b) shutting off the fire c) shutting off the feedwater d) opening the safety valve e) closing the steam discharge valve |
C
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