Chapter 8 Low Water Fuel Cut-Offs & Feedwater Controls

Question 1

The ______ operated low water fuel cut-off uses buoyancy to operate the switch.

a) Float
b) Electrode
c) Bi-Metal
d) Thermal

Answer 1

a) Float

Question 2

The type of low water cut-off that uses the conductivity of the water to operate it is the ________ type.

a) Float
b) Thermal
c) Three wire
d) Electrode Probe

Answer 2

d) Electrode Probe

Question 3

The main cause of heating boiler failure is overheating of the heating surfaces due to:

a) High water level
b) Too high a steam pressure
c) Low water level
d) Operator Error

Answer 3

c) Low water level

Question 4

A low water fuel cut-off combination pump control will ________ if the water level reaches a low level but still above the lowest permissible level.

a) Shut down the boiler
b) Start the feedwater pump
c) Close the fuel valve
d) Open the safety valve

Answer 4

b) Start the feedwater pump

Question 5

Low water levels can develop in hot water boilers due to human error.

a) True
b) False

Answer 5

a) True

Question 6

On a steam boiler you should test the low water fuel cut-off while the boiler is operating by:

a) Increasing the steam pressure
b) Blowing down the boiler
c) Opening the drain valve on the float chamber
d) Doing a “pop” test

Answer 6

c) Opening the drain valve on the float chamber

Question 7

A three wire (double pole) switch on a LWCO will shut off the fuel and sound an alarm.

a) True
b) False

Answer 7

a) True

Question 8

At normal boiler steaming rates, a condensate receiver tank should have enough water supply to keep the boiler supplied for ________ minutes.

a) 30
b) 15
c) 45
d) 60

Answer 8

a) 30