Book 1: 2-07 - Low Water Fuel Cut-Offs & Feedwater Controls

Question 1

At normal boiler steaming rates, a condensate receiver tank should contain a sufficient volume of water equivalent to the water evaporated by the boiler for a maximum period of _____ minutes.

Select one:

A. 45
B. 60
C. 20
D. 30
E. 15

Answer 1

D. 30

Question 2

Make-up water for the heating system usually comes from the:

Select one:

A. Returning condensate
B. Deaerator
C. Boiler feed water
D. City water supply
E. Boiler feed water pump

Answer 2

D. City water supply

Question 3

In a building heating system the condensate in the condensate receiver tank comes from the:

Select one:

A. Make-up water supply
B. Heating system
C. Deaerator
D. Boiler feed water
E. Economizer

Answer 3

B. Heating system

Question 4

Low water fuel cut-off devices require regular attention, the following intervals are recommended:
1. Once per shift
2. Daily
3. Weekly
4. Monthly
5. No attention is required

Select one:

A. 3,4,5
B. 1,2,4
C. 2,3,5
D. 2,3,4
E. 1,2,3

Answer 4

D. 2,3,4

Question 5

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

Select one:

A. High water conditions
B. High firing rates
C. Low steak conditions
D. Low water conditions
E. Scale build-up

Answer 5

D. Low water conditions

Question 6

The low water level fuel cut-off will shut off the fuel to the heating boiler when the water level drops below:

Select one:

A. One half of the gauge glass
B. 50 mm (2 in.) above the bottom of the gauge glass
C. 25 mm (1 in.) above the bottom of the gauge glass
D. The lowest permissible water level
E. The lowest visible part of the gauge glass

Answer 6

E. The lowest visible part of the gauge glass

Question 7

The float operated low water fuel cut-off works in the principle of:

Select one:

A. Differential pressure
B. Drum level variation
C. Steam density
D. Buoyancy
E. Temperature change

Answer 7

D. Buoyancy

Question 8

The low water fuel cut-off float is commonly used to operate both the Low water fuel cut-off switch and the:

Select one:

A. High steam pressure switch
B. Low fuel gas pressure switch
C. Feed water control switch
D. Low steam pressure alarm
E. Low feed water temperature alarm

Answer 8

C. Feed water control switch

Question 9

Possible causes of low water level include:
1. Leaks caused by the breakage or corrosion
2. Excessive blowdown
3. Automatic feedwater valve passing
4. Boiler feed pump failure
5. Excessive make-up

Select one:

A. 2,3,5
B. 1,2,3
C. 3,4,5
D. 1,2,4
E. 2,3,4

Answer 9

D. 1,2,4

Question 10

The float in the low water fuel cut-off will activate:

Select one:

A. A gate valve
B. An electrical switch
C. An electrical relay
D. A solenoid valve
E. A globe valve

Answer 10

B. An electrical switch