Book 1: 2-09 - Boiler Combustion Controls

Question 1

The infrared scanner is mounted on the end of a sighting tube in such a way that it’s temperature will not exceed:

A. 50°C (98°F)
B. 100°C (212°F)
C. 120°C (248°F)
D. 75°C (167°F)
E. 150°C (302°F)

Answer 1

A. 50°C (98°F)

Question 2

The most commonly used flame detection devices are:
1. Ultraviolet detectors
2. Thermocouples
3. Flame rods
4. Infrared detectors
5. Photoelectric cells

Select one:

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

Answer 2

C. 2,3,5

Question 3

If the pilot flame fails, no power is generated by the thermocouple preventing the _____ from supplying fuel to the burner on boiler startup.

Select one:
A. Main fuel control valve
B. Main relay valve
C. Operating control
D. Air supply valve
E. Pilot fuel control valve

Answer 3

A. Main fuel control valve

Question 4

With the photoelectric flame scanner upon loss of flame it should take no longer than _____ seconds for the gas valve to close.

Select one:

A. 2
B. 20
C.10
D. 4
E. 15

Answer 4

D. 4

Question 5

The voltage supply generated by the thermocouple is usually not more than:

Select one:

A. 0 millivolts
B. 15 millivolts
C. 100 millivolts
D. 50 millivolts
E. 30 millivolts

Answer 5

E. 30 millivolts

Question 6

The rectifying photocell, shown in Fig. 10, is also known as a _____ cell.

Select one:

A. IR
B. Cad
C. UV
D. Photoelectric
E. Rectifying

Answer 6

B. Cad

Question 7

The time take for the automatic pilot valve to close in the event of a flame detection is about _____ seconds

Select one:

A. 15
B. 4
C. 10
D. 20
E. 2

Answer 7

C. 10

Question 8

A photoelectric cell reacts to the _____ emitted by the flame.
1. Ultraviolet rays
2. Thermocouples
3. Flame rods
4. Infrared rays

Select one:

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

Answer 8

B. 1,4

Question 9

If for any reason, the burner should go out during normal operation, or the fuel should fail to ignite during startup:

Select one:

A. Increase the fuel flow
B. No action is required
C. The air to the burner must be shut off immediately
D. The fuel to the burner must be shut off immediately
E. Increase the combustion air flow

Answer 9

D. The fuel to the burner must be shut off immediately

Question 10

When the hot junction of a thermocouple is exposed to heat it’s temperature is higher than that of the cold junction and a small ______ is generated.

Select one:

A. Conductance
B. Resistance
C. Wattage
D. Amperage
E. Voltage

Answer 10

E. Voltage