Chapter 106

Question 0

What does a thermocouple consist of?

Answer 0

Two dissimilar metals (hot and cold junction)

Question 1

List three methods of detecting flame failure on heating boilers:

Answer 1

Flame rod
Thermocouple
Photoelectric cell

Question 2

The infrared scanner should be mounted so that its temperature doesn’t exceed?

Answer 2

50 Celsius

Question 3

What is used in combination with a single thermocouple to provide enough electricity to shut the main fuel valve?

Answer 3

Transformer

Question 4

How are multiple thermocouples arranged so that they can provide enough electricity to control the fuel system?

Answer 4

In series, often called a thermopile

Question 5

Flame works on what principle when detecting a flame?

Answer 5

That a flame is capable of conducting electricity

Question 6

What fuel is generally used with flame rods?

Answer 6

Gas burners

Question 7

What does a photoelectric cell react to?

Answer 7

Infrared or ultraviolet rays

Question 8

What is the photocell commonly called?

Answer 8

Scanner

Question 9

List three types of photoelectric cell scanners:

Answer 9

Infrared scanner, ultraviolet scanner, rectifying photocell

Question 10

What reacts to infrared rays produced by a flame?

Answer 10

Lead-sulphide cells

Question 11

Ultraviolet scanners are mounted as close to flame without exceeding what temperature?

Answer 11

100 degrees Celsius

Question 12

Rectifying photocell is also known as what?

Answer 12

Cad

Question 13

What does a rectifying photocell consist of?

Answer 13

Cathode and anode

Question 14

What does ASME VI code describe?

Answer 14

Procedures for testing flame safeguard devices

Question 15

How long should it take for a flame rod to shut off the fuel due to flame failure?

Answer 15

4 seconds

Question 16

The outer sheath of a thermocouple used with a pilot burner is made of what metal?

Answer 16

Copper

Question 17

High limits temperature controls shut off fuel if the water temperature is?

Answer 17

Too high

Question 18

Fuel should be shut off immediately to prevent?

Answer 18

Furnace explosions

Question 19

A thermocouple used in conjunction with a gas valve must be inserted?

Answer 19

In the flame to work effectively