*Bk 29- Gas Utilities Flashcards
What is the ignition temperature of natural gas?
And it’s flammable range?
- 1100 degrees
- 4-14%
Gas carried by service lines generally don’t exceed how much psi?
60psi
Gas mains normally 40 to 60 psi
What is the gas psi reduced to at the service meter? (This is the pressure that is supplied to the inside of a home)
1/3psi
Older mains that transport gas are what color and are made of what?
What color are newer pipes?
- Salmon beige or orange, made of plastic
- Yellow made of polyethylene
A ring on a stopcock valve indicates what?
A branch service
A flat washer on a stopcock valve indicates what about the service line?
That a plastic pipe is inserted inside an older metal pipe
What does a band on the stopcock indicate?
The service line is plastic
What can you look for at the curb to help locate which side the MSA is on?
The letter “G”
To reset an earthquake valve, how much should you turn the reset button?
1/4 of a turn
The _____ Valve is a shut off valve used on high-pressure risers and piping at industrial/commercial sites.
Nordstrom
(Larger version of a residential stopcock)
When dealing with a stuck tang (no pin driven in backing nut) during an emergency condition, you should loosen the backing nut how much?
1/4 turn only
For a faint odor of gas inside a structure, always check the condition of the _________ as a first action.
Pilot light
(If a leak is suspected, pouring soapy water over the suspected area can confirm its presence.)
What must be done before operating on a gas leak with a plastic pipe to prevent a spark?
Fog down pipe with wet water
Does a gas leak in a steel pipe create a huge spark potential?
No, the current is drawn off and safely dissipated to the ground by the conductive pipe
Small gas leaks that have caught fire may be extinguished with _______ in order to approach the shutoff valve.
Dry chemical extinguisher or CO2
For large gas leaks that have caught fire, what can you apply in order to approach the shutoff valve?
Fog pattern on hose line
Transmission lines that bring in natural gas into SoCal are 12 to 36 inches in diameter.
Pressure in such a pipeline can be as high as _____ psi
1000 psi
Redwood plugs work on gas pipes made of ____ and don’t work on ones made of ____
Steel
Polyethylene
In dealing with a curb valve with a “faucet” type handle and the valve is too deep to reach with the hand, a ____ can be used for extra reach.
Sprinkler key
Per T.B. 49:
As a precautionary measure, any oily mist or liquid encountered in any natural gas pipeline system should be presumed to contain _____. Notify hazmat.
PCB’s (polychlorinated byphenyls)
Above ground gas lines must be made of _____ and cannot be _____
Steel
Plastic
_______ gas mains are normally located underneath city streets, parallel to curbs, under grassy parkways, between the curb and sidewalk, and occasionally in alleys
Distribution
Gas _____ lines run from distribution mains to structures, via an outside riser, where pressure regulators and meters are located.
Service
What is the name of the shutoff valve on a riser used to stop the flow of gas to the gas meter?
Stopcock or service cock
Can also be called the “service shut-off valve”
Gas utilities:
Personnel should recognize and understand that a swift-kick to an earthquake valve may possibly shut off the flow of gas, when is this a viable option?
only in the event of a damaged or frozen stopcock, never done in lieu of a normal shut-off procedure
A curb valve is also referred to as an _____ Valve. These valves can be installed in addition to stopcocks and are underground ___ to ___ feet by the sidewalk
Emergency Shut-off
2 to 3 ft
(These valves are used for public assembly occupancies such as schools, hospitals, churches, etc.)
Ventilation can bring gas into proper explosive mixture with air, therefore, all sources of ignition shall be ELIMINATED prior to __________.
opening any windows
If it is determined to be UNSAFE to ENTER a structure due to a gas leak, consider what 3 things?
-Turn off gas at the meter.
-Spot apparatus in safe zones.
-Establish a water supply and prepare for fire suppression operations.
The Fire Department’s role at a gas leak outside of structures is to?
maintain public safety
The only sure way to safely check suspected areas of gas is to use a _____
combustible gas indicator
Can the bend back method be used to stop a gas leak in small diameter lines?
No, There is an extremely high potential for creating a static charge that usually accompanies the increased pressure of gas flowing from the restricted opening as the pipe is bent over
Is CRIMPING plastic pipe acceptable?
Yes, Crimping plastic pipe is acceptable as long as all tools used to work on plastic pipe are grounded
The cylinder inside a stopcock that allows or blocks the flow of gas is known as the ____
Core
It is connected to the tang and rotated by turning the tang. It is held in place by the backing nut.
What toxic gas on rare occasions, is present in leaks at natural gas compressor stations or at underground storage fields?
Hydrogen sulfide
The common odorant in natural gas is a _____ and _____ mix.
Mercapitan and thiophane
Considerations at a NATURAL GAS FIRE should include:
-Protect exposures.
-Generally, let the gas burn until the supply is shut off.
-If necessary, control evacuation and maintain site security.
-Notify The Gas Company.
Multi-meter service is a row of meters connected to a common riser. Multiple meters are also known as “______”
Headers
