chapter 7 Flashcards
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, 4
D.
1, 2, 3
E.
2, 3, 5
C. 2, 3, 4
2. Daily
3. Weekly
4. Monthly
Make-up water for the heating system usually comes from the:
Select one:
A.
City water supply
B.
Boiler feedwater
C.
Deaerator
D.
Boiler feedwater pump
E.
Returning condensate
A.
City water supply
The float in the low water fuel cut-off will activate:
Select one:
A.
A solenoid valve
B.
A gate valve
C.
A globe valve
D.
An electrical relay
E.
An electrical switch
E.
An electrical switch
The float operated low water fuel cut-off works on the principle of:
Select one:
A.
Differential pressure
B.
Temperature change
C.
Buoyancy
D.
Drum level variation
E.
Steam density
C.
Buoyancy
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.
50 mm (2 in.) above the bottom of the gauge glass
B.
The lowest permissible water level
C.
One half of the gauge glass
D.
The lowest visible part of the gauge glass
E.
25 mm (1 in.) above the bottom of the gauge glass
D.
The lowest visible part of the gauge glass
Possible causes of low water level include:
1. Leaks caused by breakage or corrosion
2. Excessive blowdown
3. Automatic feedwater valve passing
4. Boiler feed pump failure
5.Excessive make-up
Select one:
A.
1, 2, 3
B.
2, 3, 5
C.
2, 3, 4
D.
1, 2, 4
E.
3, 4, 5
D. 1, 2, 4
1. Leaks caused by breakage or corrosion
2. Excessive blowdown
4. Boiler feed pump failure
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.
60
B.
30
C.
20
D.
15
E.
45
B.
30
In a building heating system the condensate in the condensate receiver tank comes from the:
Select one:
A.
Make-up water supply
B.
Deaerator
C.
Boiler feedwater
D.
Economizer
E.
Heating system
E.
Heating system
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.
Low feedwater temperature alarm
D.
Feedwater control switch
E.
Low steam pressure alarm
D.
Feedwater control switch
The main cause of heating boiler failure is overheating of the heating surfaces due to:
Select one:
A.
High water conditions
B.
Scale build-up
C.
Low water conditions
D.
Low steam conditions
E.
High firing rates
C.
Low water conditions
A second source of feedwater may be controlled by the:
Select one:
A.
Feedwater control switch
B.
Low water fuel cut-off device
C.
Automatic blowdown device
D.
Boiler operating control
E.
Boiler drum level control
B.
Low water fuel cut-off device
