Gas Utilities Flashcards
How is gas delivered in city of Los Angeles ?
Underground service pipes
What is added to natural gas as oderants?
Mercaptian/Thiophane mix
1 pint per million cubic ft of gas
Large quantities inhaled natural gas are ok true or false
False lg quantities can cause asphyxiation
What’s the ignition temperature of Natural gas?
1100 degrees F
What’s the flammable range of natural gas?
4-14%
What’s the transmission lines pressured at ?
1000 psi
How is natural gas generally distributed
Transmission lines and distribution lines
What the size of transmission lines in Southern California
12-36” in diameter
What pressure are service gas lines ?
Medium 60psi
What pressure is the meter set assembly reduced to ?
Low pressure 1/3 psi
What are gas mains generally?
Polyethylene
What are older distribution mains?
Steel or copper
Polyethylene mains are color coded what colors?
Yellow new national standard
Pink or orange older installations
What are above ground gas lines made of ?
Must be made of steel
Where can gas distribution lines be found ?
Underneath city streets Parallel to curbs under feast parkways between curb and side walk and occasional alley
Where can meter set assembleies be found?
Outside set
Underneath stair set
Curb meter set
Cabinet set
What additional categories are MSAs
Residential
Industrial
Multiple gas meter
What’s the basic MSA consist of
Piping,
Shut off valve
Regulator
Gas meter
What’s another name for shut off valve?
Stopcock or service cock
What are special interest of stopcock for personnel shitting of to consider?
A ring around stopcock indicates a branch service
Flat washer indicates platic pipe inside older metal pipe
A band indicates service line in plastic
Up the rider the regulator reduced from med to low pressure
Next pipe fittings leading to gas meter after meter gas flows through pipes to structure
What is required by Cal OSHA mark the location where device line passes beneath curb and indicate which side of building the MSA is located?
A G chiseled or painted
What are some MSA equipped with?
Vibration sensitive shut off valve
Earthquake valves
Turning reset button ______ completes the reset of device
One quarter turn
What are industrial shut off valves known as ?
Nordstrom valves
What kind of meter is used in industrial gas lines?
Rotary meter
MSA in multiple habitation or commercial occupancies are equipped with Main and individual shut offs true or false ?
True
What is branch service mean?
In multiple structures and commercial areas. May be served by single service called a standard service Main
The building furthest away is standard service and the rest are branch off of that pipes
To turn off gas Sgt off valve should be ?
Crosswise
How far can you turn the packing but when using tow wrenches
1/4 turn if loosen too much core can fly out and leak medium pressure 40-60psi gas
What are curb valves ?
Emergency shut off valves
Can be found schools churches hospitals
Located near Pepe Perry line 2-3ft underground marked by a lid marked gas company
Who carries equipment that can detect gas and its LEL?
Haz Mat companies
Is crimping plastic piping ok
As Long tools are grounded
The gas company stated that its product is ____ free from impurities
97%
How can you prevent ignition from plastic pipe?
Fogging down with wet water
What are considerations of natural gas fire
Protect exposures
Let gas burn until supply is shut off
Control evacuation and site security
Notify gas company
Small fires may be extinguished with?
Dry chemical or CO2 if necessary
Large fires involving natural gas
Fog stream can be used to approach valves try to keep water out of excavations
