Book 29 Flashcards
common source of heat in buildings due to its convenience, abundance, and relatively low cost
Natural gas
natural gas delivered to the property, via
underground service pipes
Pure natural gas is completely
odorless
For the purpose of leak detection, what is added so that as little as 1% of natural gas in the air can be detected?
Odorant
What is the common odorant , which is used in solution of 1 pint per million cubic feet of gas?
Mercapitan/Thiophane Mix
Natural gas, when inhaled in limited concentrations is considered what?
Non-toxic and not hazardous
Is natural gas lighter or heavier than air?
Lighter
Natural gas has a ignition temp of what?
1100 degrees
Natural gas has a flammable range between?
4 and 14 percent
What do transmission lines of natural gas maintain pressure up too?
1000 psi
What are used to maintain appropriate flow and pressures for natural gas?
Booster compressor stations at specific intervals
To compensate for fluctuating, what do gas companies maintain?
Underground or above ground storage facilties
How is natural gas generally distrusted by?
Combination oof transmission lines and distribution lines
Transmission lines bring natural gas into the Southern Cali area and vary in diameter from
12 to 36 inches
How is natural gas distributed to Gas Company Customers?
By distribution mains
Gas is carried by service lines, as medium pressure, which normally does not exceed what psi?
60 psi
At the service meter (Meter Set Assembly) the pressure is reduced to a low pressure (approximately what psi?
1/3 psi
What are distribution lines generally made of ?
Polyethylene
What are older existing gas distribution mains made of?
Steel or cooper, rare to find
What color are the polyethylene gas mains?
Yellow, national color code for newer installations
What color are older gas mains?
Plastic pipe can be pink (salmon beige) or orange in color
What will be running the length of the pipe for location plastic gas lines below ground?
Wire
What type of material will be gas pipes above ground?
Steel
Where are gas distribution mains normally located?
Underneath city streets Parallel to curbs Under grassy parkways Between the curb and sidewalk Occasionally in alleys
How is natural gas distributed from a distribution main to the customer?
By a service line
How is the pressure for a customer line regulated and measured?
By a regulator and gas meter
Gas companies refer to gas meters as what?
MSA= meter set assemblies
Where can meter set assemblies be located at?
- Outside sets: outside the structure
- Underneath sets: underneath structures, stairs, etc.
- curb meter box: vault underneath a sidewalk
- cabinet set: enclosure on the exterior of the structure
What are MSA categorized as?
Residential
Industrial
Multiple Gas Meter
The basic MSA consists of what?
Piping
Shut-off valve
Regulator
Gas Meter
The pipe rising vertically from the ground close to the exterior wall of structure is called a what?
Riser
Tracing the riser up from the ground the first fitting is the shut -off valve called the what?
Stopcock or service cock
-primary concern for shutting off the gas to a structure
A ring on the stopcock valve indicates what?
Branch service
A flat washer on the stopcock valve indicates that the service line is a what?
Plastic pipe inserted inside a older metal pipe
A band on the stopcock valve indicated the service line is what?
Plastic
Up the riser, past the stopcock, is a flat circular device called a what?
It reduces medium gas pressure up to what psi to a relatively low level of approximately what?
Regulator
60 psi to 1/3 psi
The gas meter measures what?
The amount of gas that is used
When locating a MSA what do you initially look for?
A “G” - either chiseled or painted on the curb
Required by Cal-OSHA, marks the location where the service love passes beneath the curb and indicated which side of the building the MSA is located
Where are MSAs and shut-off valves normally located at?
Outside wall of a structure. Location is easily accessible to gas company personnel who read the meters for billing purposes
If an MSA is not visible along an outside wall, it us usually found in what following locations?
- Crawl space, under building
- beneath outside staircase
- outdoor cabinet, new condos
- underground garage
- sidewalk or parkway vault, side of building
- basement, shut-off usually accessible from outside building
- subsurface, parkway or sidewalk
Some MSA’s may be equipped with an emergency vibration-sensitive shut-off device known as what?
Earthquake valve
Marketed by private industry and are normally mounted on the discharged side, right side as you face the meter, of the MSA
What may possibly shut off the flow of gas?
Swift-kick
How do you reset the Earthquake valve?
Turning a reset button, one-quarter turn, completes reset of this device
In Industrial MSA’s, what can be used to utilized to control the flow of gas in the service main
-curb valve & curb valve extension handle
Industrial shut- off valves that are used for high pressure applications are known as what?
Nordstrom Valves
Nordstrom valves are larger than standard shut-off valves and may require more effect and larger tools to shut off the flow of gas. Some have gate valves with wheel handles, which direction do you turn it to close?
Clockwise
Industrial applications that are high pressure can use how many regulators in series to regulate the gas pressure?
Two regulators
What type of meter is used to regulate the high pressure and handle quick surges?
Rotary meter
Meters under the sidewalk are called what and common in what area?
Curb meters, commercial areas
The lid over the curb meter is made of what?
Lightweight concrete or fiberglass set in a metal frame
How can a curb meter be easily identified?
Gas company markings
Industrial MSA’s are physical what than MSAs used for residential applications?
Physically Larger
Multiple habitational or commercial occupancies are often equipped with multiple what?
MSA’s:
Provide a master stopcock and a separate meter and stopcock for each unit
Who is required to identify the individual MSA’s, as to which unit or building they serve?
GAs Co.
Who do you notify if the identification of has worn away and can have the meters properly marked?
Gas Co.
In some commercial areas, multiple structures may be commonly serviced by a single service pipe called what?
Standard service main
What identifies a standard service man that multiple structures may be commonly serviced by a single service pipe?
A metal ring
In a branch service, the occupancy that s further from the supply main is a what?
The occupancies are what?
Standard Service/Branch service
All MSA’s that are served from the branch main will be identified by what?
A ring at the stopcock
To turn off the flow of gas, turn the ____, _________, to the flow of gas; crosswise to the pipe
Tang; crosswise
What shape can the tang on some stopcock be?
Square
Tangs can be easily turned with which tool?
Crescent wrench
If a tang appears to be stuck, do not apply too much pressure. If the tang breaks off, it will be difficult to stop the flow of gas. It is recommended that who service a stuck tang?
The Gas Co.
How do you approach a stuck tang in a EMERGENCY CONDITIONS:
- 2 wrenches: 1 on the tang, other on the backing nut
- Hold tang steady, loosen backing nut ONE-QUARTER TURN ONLY!
If the backing nut is loosened to far, the core can fly out, leaking medium pressure gas, at __ to __ psi.
40 to 60 psi
Newer stopcock have a pin driven into the backing nut, and bolt, and cannot be loosened. What are some other options to unstuck a tang:
- Give backing nut a tap with non-metallic hammer, freeing the core
- Turn the tang, one-quarter turn, to stop the flow of gas; half-turn will continue to let the gas flow
- Tighten backing nut to lock the core in the “OFF” position
What is a larger version of a residential stopcock? It is used on high-pressure risers and piping, at industrial/commercial sites, and comes in various sizes to fit different diameter pipes.
Nordstrom Valve
The tang on a Nordstrom valve can only be turned how, in either direction, ensuring the “ON” and “OFF” positions are easy to locate.
One-Quarter Turn
Some industrial meters are equipped with a gate valve that has a wheel handle (similar to an OS&Y), turning the handle in which direction several revolutions will shut off the gas
Clockwise
What valves can be installed in addition to stopcock at public assembly occupancies, normally located near the property line, by a sidewalk.
They are 2 to3 feet underground and under a small metal, concrete or fiberglass lid; with “Gas Company” markings in raised letters.
Curb Valves- also referred to as an Emergency Shutoff Valve
To gain access to a curb valve, lift the lid with a common utility tool, screwdriver, in the hole. If the lid is stuck, and additional leverage is necessary, insert the point of a what in the hole and apply proper leverage.
Pickhead Axed
The curb valve has what type of handle to it and which direction do you turn it to stop the flow of gas?
“Faucet” type handle, turn CLOCKWISE
If the curb valve is too deep to reach with the hand, what can you use for extra reach?
Sprinkler Key
Natural gas emergencies can be divided into 3 categories:
- Inside Leak
- Outside leaks
- Leaks resulting in fires
The greatest danger results from gas leaks where, due to the potential for ignition and explosion
Inside structures