chapter 9

Question 1

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

A.
IR

B.
Cad

C.
Rectifying

D.
UV

E.
Photoelectric

Answer 1

B.
Cad

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.
1, 2, 3

B.
1, 2, 4

C.
2, 3, 5

D.
3, 4, 5

E.
2, 3, 4

Answer 2

C.
2, 3, 5
2. Thermocouples
3. Flame rods
5. Photoelectric cells

Question 3

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.
Mixed

D.
Vapourized

E.
Gaseous

Answer 3

E.
Gaseous

Question 4

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

A.
The ionized particle principle

B.
Flame rectification

C.
Photoelectric scanning

D.
Ultraviolet detection

E.
Infrared detection

Answer 4

B.
Flame rectification

Question 5

The time taken for the automatic pilot valve to close in the event of a loss of flame detection is about _____ seconds
Select one:

A.
4

B.
15

C.
10

D.
20

E.
2

Answer 5

C.
10

Question 6

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

A.
Serious explosion

B.
Water tube explosion

C.
Fire tube failure

D.
Boiler drum failure

E.
Spike in steam production

Answer 6

A.
Serious explosion

Question 7

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

A.
75°C (167°F)

B.
50°C (98°F)

C.
150°C (302°F)

D.
100°C (212°F)

E.
120°C (248°F)

Answer 7

D.
100°C (212°F)

Question 8

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

A.
100 millivolts

B.
50 millivolts

C.
0 millivolts

D.
30 millivolts

E.
15 millivolts

Answer 8

D.
30 millivolts

Question 9

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.
Pilot fuel control valve

B.
Air supply valve

C.
Operating control

D.
Main fuel control valve

E.
Main relay valve

Answer 9

D.
Main fuel control valve

Question 10

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.
Increase the combustion air flow

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

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

Answer 10

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

Question 11

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

A.
Liquid

B.
Gaseous

C.
Mixed

D.
Vapourized

E.
Solid

Answer 11

E.
Solid

Question 12

The infrared scanner is mounted on the end of a sighting tube in such a way that its temperature will not exceed:
Select one:

A.
150°C (302°F)

B.
120°C (248°F)

C.
75°C (167°F)

D.
50°C (98°F)

E.
100°C (212°F)

Answer 12

D.
50°C (98°F)

Question 13

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

A.
2, 4

B.
2, 3

C.
1, 2

D.
1, 3

E.
1, 4

Answer 13

E.
1, 4
1. Ultraviolet rays
4. Infrared rays

Question 14

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.
20

B.
10

C.
2

D.
4

E.
15

Answer 14

D.
4

Question 15

When the hot junction of a thermocouple is exposed to heat its temperature is higher than that of the cold junction and a small _____ is generated.
Select one:

A.
Wattage

B.
Amperage

C.
Resistance

D.
Conductance

E.
Voltage

Answer 15

E.
Voltage

Question 16

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.
200°C (392°F)

B.
75°C (167°F)

C.
150°C (302°F)

D.
120°C (248°F)

E.
100°C (212°F)

Answer 16

D.
120°C (248°F)

Question 17

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

A.
Holding the solenoid open

B.
Supplying fuel to the burner

C.
Heating the rod

D.
Conducting electricity

E.
Holding the solenoid closed

Answer 17

D.
Conducting electricity

Question 18

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

A.
Reference junction

B.
Metering junction

C.
Hot junction

D.
Electric circuit

E.
Cold junction

Answer 18

C.
Hot junction

Question 19

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

A.
Lead sulphide

B.
Sodium sulphide

C.
Sodium chloride

D.
Lead sulphate

E.
Lithium bromide

Answer 19

A.
Lead sulphide