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 it takes 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

Question 11

A flame rod uses the principle that a flame is capable of:
Select one:

A. Holding the solenoid open
B. Heating the rod
C. Conducting electricity
D. Supplying fuel to the burner
E. Holding the solenoid closed

Answer 11

C. Conducting electricity

Question 12

The flame rod method of scanning is often referred to as:
Select one:

A. Ultraviolet detection
B. Infrared detection
C. Photoelectric scanning
D. Flame rectification
E. The ionized particle principle

Answer 12

D. Flame rectification

Question 13

The infrared scanner contains a _____ cell which reacts to infrared rays.
Select one:

A. Lithium bromide
B. Sodium chloride
C. Sodium sulphide
D. Lead sulphide
E. Lead sulphate

Answer 13

D. Lead sulphide

Question 14

In an oil fired boiler the fuel enters the furnace in a _____ state mixes with combustion air and is ignited.
Select one:

A. Vaporized
B. Gaseous
C. Liquid
D. Mixed
E. Solid

Answer 14

A. Vaporized

Question 15

Each automatically fired hot water boiler shall have a high limit temperature control that will shut off the fuel supply to the boiler to prevent the water from exceeding the maximum allowable temperature of:
Select one:

A. 150°C (302°F)
B. 120°C (248°F)
C. 200°C (392°F)
D. 75°C (167°F)
E. 100°C (212°F)

Answer 15

E. 120°C (248°F)

Question 16

The scanner is mounted as close to the flame as physically possible without subjecting it to a temperature over:
Select one:

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

Answer 16

E. 100°C (212°F)

Question 17

A thermocouple consists of two dissimilar wires welded together at one end to form a:
Select one:

A. Cold junction
B. Metering junction
C. Electric circuit
D. Reference junction
E. Hot junction

Answer 17

E. Hot junction

Question 18

In a gas fired boiler the fuel enters the furnace in a _____ state mixes with combustion air and is ignited.
Select one:

A. Liquid
B. Solid
C. Gaseous
D. Mixed
E. Vaporized

Answer 18

C. Gaseous

Question 19

Unburned fuel collecting in the furnace can mix with the combustion air and may ignite, causing a
Select one:

A. Spike in steam production
B. Boiler drum failure
C. Serious explosion
D. Fire tube failure
E. Water tube explosion

Answer 19

C. Serious explosion

Question 20

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

Select one:

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

Answer 20

B. 50°C (98°F)