Chapter 12 Gas Utilities Flashcards Preview

Truck Company Operations Mittendorf 1998 > Chapter 12 Gas Utilities > Flashcards

Flashcards in Chapter 12 Gas Utilities Deck (44):
1

What odorant is commonly added to natural gas?

Thiophane

2

Newer distribution mains of polyethylene are recognizable by what color?

Pink or bright orange

3

What are the primary components of a meter set assembly?

Piping, shutoff valve, regulator, and meter

4

What does a green band on a riser near a stopcock valve indicate?

The service line is plastic

5

Why are rotary meters used?

To regulate high pressures and to handle quick surges

6

To turn off the flow of gas with a stopcock valve, you should turn the tang to what position?

Crosswise to the pipe

7

To eliminate the flow of gas to a multiunit dwelling, which stopcock should you shut off?

The stopcock on the common riser

8

Who should restore the flow of gas to a building when the supply has been shut off?

Only a gas company representative

9

What are the three categories of natural gas emergencies?

Inside leaks, outside leaks, and leaks resulting from fires

10

Normally, what type of gas leak poses the greatest danger?

Gas leaks inside structures that present the potential for an explosion

11

Natural gas supplies approx. ___ of the energy requirements of the U.S.

1/3

12

What hydrocarbons is natural gas generally comprised of?

Methane and Ethane

13

What chemical impurities can be present in natural gas?

Nitrogen, carbon dioxide, hydrogen sulfide, helium

14

What percent of natural gas is methane?

97 PERCENT

15

What may be used in natural gas at 400 parts per million and used for identification? how?

Helium
Seepage from underground storage or breaks in gas lines can be differentiated from seepage from natural underground pockets

16

What concentrations is Thiophane used in natural gas?

1 pint per million cubic feet

17

Natural gas transmission lines have pressures up to what PSI?

1000 PSI

18

How big are transmission lines?

12-36 inches

19

What pressure can be found in distribution mains?

60 psi

20

What are distribution mains made out of?

Older--steel or copper
Newer--polyethylene

21

What color are polyethylene distribution mains?

Pink or bright orange

22

What is the pressure inside customer gas lines?

1/3 psi

23

How is the pressure in a customer line regulated?

regulator and gas meter

24

What is a MSA and what 3 locations can these be found?

Meter Set Assembly

Outside sets--outside of structure
underneath sets--underneath structures, stairs..
Curb meter box--vault underneath sidewalk

25

What does a MSA consist of?

Piping
shut-off valve
regulator
gas meter

26

What is a riser?

pipe rising vertically from the ground close to the exterior wall of a structure

27

What is a shut-off valve called?

stopcock or service cock

28

What does a flat washer on the stopcock indicate?

service line is plastic pipe inserted inside an older metal pipe

29

What does a ring on the stopcock valve indicate?

branch service

30

What does a band (normally green) on the riser near the stopcock indicate?

service line is plastic

31

What pressure does the regulator receive? what does it reduce it down to?

60 psi--down to 1/3 psi

32

What is an earthquake valve?

emergency vibration-sensitive shutoff device

33

What is a Nordstrum valve? How far can the tang be turned?

an industrial shutoff valve used for high-pressure applications

The tang can only be turned 1/8th turn

34

When dealing with branch service, what occupancy has the standard service? the others are branch service

the occupancy farthest from the supply main

35

Generally, what is the safest and most direct method of eliminating the flow of gas to a structure?

turn it off at the stopcock

36

What does a basic stopcock consist of?

Internal core
Casing
Washer
backing nut
circlip

37

What does a G chiseled or painted on the curb indicate?

required by OSHA--shows the location where the service line passes beneath the curb and indicates the side of the building on which the MSA is located

38

In an emergency situation where the stopcock wont turn, how might you free it up to turn?

Loosen the backing nut up ONE TURN ONLY. tap the backing nut with non-metallic hammer,and turn 1/4 turn

39

What are the 3 primary objectives when dealing with a gas leak emergency?

Safety
Protection of Property
Prompt and efficient control of incident

40

What 3 categories can natural gas be divided into?

Inside leaks
Outside leaks
Leaks resulting in fires

41

What is a service entrance cock?

It is a master valve where the service enters the building

42

What is the best immediate procedure for responding to an outside leak?

Call the gas company

43

Of all the decisions to be made, what has the most variables?

Where to stop a leak

44

Pipe lines may contain hazardous contaminates known as what?

PCBs--Polychlorinated biphenyls