E3: Use Codes, Regulations / Standards to Size Gas Piping Systems

Question 1

What is considered the consumer gas piping system?

Answer 1

The fuel gas from point of supply –> gas burning appliance

Question 2

What is the gas fitter responsible for?

Answer 2

Installing a pipe system that is capable of supplying enough fuel to each gas-fired appliance

Question 3

What are factors that affect the gas rate of flow?

Answer 3

1) Relative density of the gas
2) Length of pipe
3) Pressure drop
4) Diameter of pipe

Question 4

How can we decrease pressure drop?

Answer 4

Through good engineering practices

Question 5

What happens if there is too great of a pressure drop?

Answer 5

The system will be very noisy
- Sonic velocity = speed of sound dt increase flow of gas

Question 6

What is considered low pressure?

Answer 6

14” WC (= 0.5 psi)

Question 7

What is considered high pressure?

Answer 7

2 psi or more

Question 8

Pipe size is up to the?

Answer 8

Installer - determining pressure drops

Question 9

What is the sequence of the pipe system in the gas code book?

Answer 9

1) Type of Gas
2) Type of pipe
3) System supply pressure
4) Pressure drop

Question 10

Does type K tubing have larger or smaller inside diameter than types G and L?

Answer 10

Smaller

Question 11

Are CSST pipe table in the Gas code book?

Answer 11

No, have to go by manufacture supplied sizing table

Question 12

What is the most important factor affecting flow of gas?

Answer 12

Pressure Drop

Question 13

What are pipe loads?

Answer 13

it expresses the volume of fuel that must pass through a pipe each hour

Question 14

How are pipe loads determined?

Answer 14

by all the appliance max inputs that are connected to that pipe

Question 15

What are the capacity table pipe loads expressed in?

Answer 15

MBH or kW

Question 16

What happens if the required load demand is not shown on that table?

Answer 16

Go to the next larger table value.

Question 17

The longer the length of run of pipe =

Answer 17

the greater the pressure drop that will occur for a given flow rate

Question 18

In order to ensure min pressure drop, what must happen?

Answer 18

pipe sizes will need to increase for systems w/ longer runs

Question 19

How does one obtain the pipe length of a system?

Answer 19

Take the distance from the system supply meter (or regulator) –> furthest appliance

Question 20

What is the longest measured run (LMR)?

Answer 20

the distance that represents the worst case scenario

Question 21

What % is added in to account for fittings?

Answer 21

20%

Question 22

For all low pressure and 2” psig tables, has the 20% fitting allowance been added in?

Answer 22

Yes

Question 23

What is it considered when branch lines are connected within 2’ of the outlet of a meter or pressure regulator?

Answer 23

Considered to be a manifold

Question 24

How are lines connected to the manifold sized?

Answer 24

Independently of the rest of the system.
Each one having an individual longest measured run

Question 25

What length is assumed for the manifold?

Answer 25

Zero length
- It’s size must be = or greater than the outlet size of the regulator

Question 26

Most gas appliances are not designed to accept inlet pressures of what?

Answer 26

Over 0.5psi (3.5kPa)
a line pressure regulator would be required before appliance (for 2psi systems)

Question 27

What happens if a pressure regulator is located more than 2’ before the inlet of the appliance?

Answer 27

a multiple pressure piping system is created
- each pressure zone will need to be sized separately

Question 28

What is high pressure gas?

Answer 28

Anything over 0.5psig

Question 29

What is low pressure sizing

Answer 29

when fittings are included in table

Question 30

What is high pressure sizing?

Answer 30

When fittings are not included in that table