Chapter 1-2

Question 1

Natural gas has a boiling point of approximately what ?

Answer 1

-258f

Question 2

Odourant added to natural gas to give it a “rotten eggs smell” ?

Answer 2

Mercaptan

Question 3

Natural gas is approximately what % of methane ?

Answer 3

85-90%

Question 4

The specific gravity of natural gas is approximately what ?

Answer 4

0.60

Question 5

The specific gravity of air is equal to what ?

Answer 5

1.0

Question 6

What do flame characteristics indicate ?

Answer 6

The quality of combustion that is taking place

Question 7

Required air/gas ratio is what ?

Answer 7

The cubic feet or cubic metres required to burn one cubic foot of natural gas without having any excess air found in the products of combustion

10/1
10 being air 1 being natural gas

Question 8

What does a yellow flame indicate ?

Answer 8

Indicates there is no premixing of natural gas with the required air for combustion

Question 9

What does a blue flame indicate ?

Answer 9

A higher temperature and is the result of some premixing of the fuel with the required air for combustion

Question 10

1. What is primary air ?
2. What is secondary air ?

Answer 10

1. Air mixed with the fuel prior to its ignition (no flame)
2. Air mixed with fuel around the flame as in the yellow flame

Question 11

What is excess air ?

Answer 11

Air supply above the ideal or theoretical amount

Question 12

What is the composition of air ?

Answer 12

20% oxygen
80% nitrogen

Question 13

What is the heating value for natural gas ?

Answer 13

1000 BTU/cf

Question 14

How is the gas consumption of an appliance indicated ?

Answer 14

Rated on a hourly basis
1. Flow Rate = CFH
2. Heat Rate or Input Rate = Btuh

Question 15

What is the Input Rate/Hear Rate formula ?

Answer 15

Input Rate (Btuh) = heating value of the gas x gas flow rate

Question 16

Flow Rate formula ?

Answer 16

Flow Rate (cfh) = Input Rate / Heating value of the gas

Question 17

What is the flame temperature for Natural Gas ?

Answer 17

3500f

Question 18

What is the flame speed for natural gas ?

Answer 18

1ft/sec

Question 19

What is the ignition temperature for natural gas ?

Answer 19

1200f

Question 20

What are the limits of flammability?

Answer 20

Upper and lower limits percentage of air/gas mixture that will support combustion
Lower limit = 4%
Upper limit = 14%

Question 21

When the combustion of the fuel is not controlled within the confines of a burner system, the limits of flammability can be called the what ?

Answer 21

Explosive limits
Lower and upper explosive limits
L.E.L = 4%
U.E.L = 14%

Question 22

Pressure of a gas is determined by what two significant factors ?

Answer 22

Volume and Temperature

Question 23

What is Boyles Law ?

Answer 23

The volume of a gas varies inversely to the pressure, provided the temperature of the gas remains constant

Question 24

What are Charles laws 1 and 2 ?

Answer 24

1. The pressure of a gas varies directly with the temperature, provided that the volume of the gas remains constant
2. The volume of a gas varies directly with the temperature provided that the pressure of the gas remains constant

Question 25

Definition of flow

Answer 25

Movement of gas from a high pressure area to a low pressure area Relative to the pressure difference between two area

Question 26

Definition of pressure drop

Answer 26

A partial loss of total energy or type of “resistance”

Question 27

Pressure drop depends on what 5 factors ?

Answer 27

1. Length of run of gas pipe 2. Size of the gas pipe 3. Number of fittings 4. Size of the flow rate 5. Specific gravity of the gas

Question 28

What is absolute pressure ?

Answer 28

Pressure measurement of a gas from a perfect or complete vacuum.

Question 29

What is atmospheric pressure ?

Answer 29

Pressure the atmosphere exerts on the earths surface. Measured in pounds per square inch absolute (PSIA)

Question 30

What is gauge pressure ?

Answer 30

Pressure measurement taken by a pressure gauge in which zero is calibrated at local atmospheric pressure

Question 31

How to determine pressure drop in a gas line

Answer 31

Working pressure at gas meter outlet - working pressure at appliance