Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Sheet Metal 2nd Period AP > Gas line sizing > Flashcards

Gas line sizing Flashcards

1
Q

NPS stands for?

A

(Nominal pipe size) As the pipe gets stronger the wall thickness increases and the inner diameter decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Consideration when sizing a gas line?

A
  • Type of fuel
  • Length of piping (longest run)
  • Individual branch loads
  • Maximum flow capacity
  • Type of materials to deliver the gas
  • Within allowable maximum pressure drop
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where is the gas load for the appliance determined from?

A

Gas load for the appliance will be determined from the rating plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Maximum pressure drop Natural gas?

A

1 inch WC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Maximum pressure drop Propane?

A

1 inch WC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

If pressure drop exceeds the maximum?

A

The gas line is probably undersized and a larger line may need to be installed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of gas piping materials can be used?

A

Steel
Cooper
Polyethylene (plastic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What schedule of black iron pipe is most commonly used for gas connections?

A

Pipe-schedule 40 steel.

For residential it is threaded and rated for a maximum of 125 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the minimum diameter for threaded pipe used for natural gas, unless it is schedule 80?

A

Threaded pipe for natural gas must not be smaller than 1/2 inch diameter unless it is schedule 80

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When can pipe used for propane be smaller than 3/8 inch?

A

Pipe used on propane may be smaller then 3/8 inch if it is used for a branch line to a single appliance no longer than 25 feet.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What type of fittings are to be used with steel pipe?

A

Steel or malleable iron fittings are to be used with steel pipe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the maximum size of steel pipe that can be threaded in a gas piping system?

A

Maximum size steel pipe that can be threaded in a gas piping system is 2”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What materials can tubing be made of?

A

Tubing can be cooper or steel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How can copper be joined, and what must it be pressure rated for?

A

Cooper can be joined by flaring, brazing or compression fittings and must be pressure rated for 125 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Types of cooper:

Type K used for?

A

Underground gas, oil and water lines as well as plumbing and HVAC above ground, very thick wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Types of cooper:

Type L used for?

A

Plumbing and heating systems, medium wall thickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Types of cooper:

Type M used for?

A

Water distribution systems, heating and sprinkler system, thin wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Types of cooper:

Type G used for?

A

All above ground and indoor natural gas and propane installations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Plastic pipes used for?

A

Outdoors, underground. Is joined using thermal fusion or compression. Tracer wire required. Does’t work with liquid propane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Hose minimum rated working pressure for hose and hose fittings?

A

350 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Maximum length of hose on a permanent installation?

A

10’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Minimum length of hose on a construction heater?

A

15’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Maximum length of hose on a portable appliance (BBQ)?

24
Q

How must CSST be protected if run inside a wall?

A

CSST (corrugated stainless steel tubing) if run inside a wall must be protected from damage using protection plates

25
How are bushings allowed to be used?
Bushings are allowed but they cannot be nested
26
How can appliances such as a gas range or dryer be connected?
Appliances such a gas range or dryer can be connected with **flex** connector
27
What is the maximum length of a flex connector on a vented appliance?
2'
28
What is the maximum length of a flex connector on an unvented appliance?
6'
29
What length of unthreaded pipe must be exposed when a pipe protrudes through a ceiling or wall?
1"
30
What length of unthreaded pipe must be exposed when a pipe comes through a floor?
2"
31
What is the minimum depth (length) of a drip/dirt pocket, and how is it determined?
Drip/dirt pocket is designed to collect water, liquids, dirt, debris and the depth (length) of the pocket must be **minimum 3"** or the **diameter of the piping** it serves whichever is greater
32
Which 3 fittings cannot be used in a gas piping system?
- Street tees - Street elbows - Close nipples
33
What is the minimum depth at which gas lines must be buried, and how does this change for commercial installations when gas lines traverse a driveway or parking lot?
15" and 24"
34
What color must gas lines be painted in commercial buildings?
Yellow
35
Where must yellow band markings be placed for gas or propane lines?
Yellow band markings at 20' gas or propane markings at 20'
36
Where must yellow bands be placed on residential copper tubing?
Residential cooper tubing must have yellow bands at **6'**
37
Where should the shut-off be installed in relation to the appliance, and how far can it be from the appliance?
Shut off will be installed on the **final drop or rise and close as possible** to the valve train of the appliance usually within **2'**. It can be located **up to 50'** away from the appliance as long as it is accessible and clearly tagged.
38
If gas line on the roff, what is the maximum length of pipe before an expansion loop is required?
100'
39
What is the pressure and duration for rough-in testing?
15 psig for 15 min
40
What is the duration and pressure for finish testing?
10 minutes at working pressure
41
What is the allowable pressure drop when pressure testing a gas line?
0" wc
42
What is the minimum size of the face on a test gauge?
3" in diameter Visibility Accuracy Durability
43
After the pressure test where should the air be vented to, and how far should the purge point be from a building or air intake?
The air should be vented to a **safe location** and the purge point should not be any closer than **10'** to a building or air intake.
44
What type of inert gas should be used when purging a gas line that is 4” or larger?
Carbon Dioxide or Nitrogen
45
What is **standing pressure**, and what are the typical settings for natural gas and propane?
**Standing pressure** is the pressure in a gas line that taken downstream of the service regulator and/or the second stage regulator and upstream of the appliance regulator with only the pilot burning. It is usually set at **7" wc for natural gas** and **11" wc for propane**.
46
What is **operating pressure**, and where is it measured in the gas line?
**Operating pressure** is the pressure in the gas line taken downstream of the service regulator and upstream of the appliance regulator with the appliance's main burner operating.
47
What is **differential pressure**, and what is the maximum allowable pressure drop?
**Differential pressure** (also called pressure drop or pressure loss) is the difference between the standing pressure and operating pressure. The maximum pressure drop is 1" wc
48
What is **manifold pressure**, and where is it measured?
**Manifold pressure** is the pressure at the burner. It is taken downstream of the appliance regulator with the main burner operating.
49
How can inches of water column be converted to psi?
nches of water column can be converted to psi by multi plying by 0.0361.
50
1 psi in "wc?
28" wc
51
14"wc in psi?
0.5 psi
52
When is it necessary to add equivalent length for fittings in a 2 psi gas line installation?
In a 2 psi gas line installation, **you will need to add equivalent length for fittings if you have more than a reasonable amount**.
53
How far must a vent termination be from a moisture exhaust duct?
Vent termination must be at least **3'** from a moisture exhaust duct
54
What is the maximum pressure drop allowed in 2 psig systems, and where can it be found?
2 psig systems allow up to a 75% pressure drop depending on the sizing table. Table A.4 with a pressure drop of 1.5 psig
55
56

Sheet Metal 2nd Period AP (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions