E3: Use Codes, Regulations / Standards to Size Gas Piping Systems Flashcards
What is considered the consumer gas piping system?
The fuel gas from point of supply –> gas burning appliance
What is the gas fitter responsible for?
Installing a pipe system that is capable of supplying enough fuel to each gas-fired appliance
What are factors that affect the gas rate of flow?
1) Relative density of the gas
2) Length of pipe
3) Pressure drop
4) Diameter of pipe
How can we decrease pressure drop?
Through good engineering practices
What happens if there is too great of a pressure drop?
The system will be very noisy
- Sonic velocity = speed of sound dt increase flow of gas
What is considered low pressure?
14” WC (= 0.5 psi)
What is considered high pressure?
2 psi or more
Pipe size is up to the?
Installer - determining pressure drops
What is the sequence of the pipe system in the gas code book?
1) Type of Gas
2) Type of pipe
3) System supply pressure
4) Pressure drop
Does type K tubing have larger or smaller inside diameter than types G and L?
Smaller
Are CSST pipe table in the Gas code book?
No, have to go by manufacture supplied sizing table
What is the most important factor affecting flow of gas?
Pressure Drop
What are pipe loads?
it expresses the volume of fuel that must pass through a pipe each hour
How are pipe loads determined?
by all the appliance max inputs that are connected to that pipe
What are the capacity table pipe loads expressed in?
MBH or kW
What happens if the required load demand is not shown on that table?
Go to the next larger table value.
The longer the length of run of pipe =
the greater the pressure drop that will occur for a given flow rate
In order to ensure min pressure drop, what must happen?
pipe sizes will need to increase for systems w/ longer runs
How does one obtain the pipe length of a system?
Take the distance from the system supply meter (or regulator) –> furthest appliance
What is the longest measured run (LMR)?
the distance that represents the worst case scenario
What % is added in to account for fittings?
20%
For all low pressure and 2” psig tables, has the 20% fitting allowance been added in?
Yes
What is it considered when branch lines are connected within 2’ of the outlet of a meter or pressure regulator?
Considered to be a manifold
How are lines connected to the manifold sized?
Independently of the rest of the system.
Each one having an individual longest measured run
What length is assumed for the manifold?
Zero length
- It’s size must be = or greater than the outlet size of the regulator
Most gas appliances are not designed to accept inlet pressures of what?
Over 0.5psi (3.5kPa)
a line pressure regulator would be required before appliance (for 2psi systems)
What happens if a pressure regulator is located more than 2’ before the inlet of the appliance?
a multiple pressure piping system is created
- each pressure zone will need to be sized separately
What is high pressure gas?
Anything over 0.5psig
What is low pressure sizing
when fittings are included in table
What is high pressure sizing?
When fittings are not included in that table
