Emegeincies 2 Flashcards
Natural gas is delivered via pipeline to NYC at approximately 700-1400PSI .ITS REGULATED DOWN TO LOWER pressures to distribution mains. This distribution mains can be high,medium and low .this pressures are
High -60 PSI
MED- 3-15 psi
Low- 1/4 psi
Properties of natural gas are
Mainly of methane but contains ethane propane and nitrogen Colorless Odorless Lighter than air Explosive range 5%-15% Non-toxic Asphyxiant
In NYC PIPING CAN be steel , plastic cast iron or copper . What piping is not allowed inside structures in NYC
Plastic and copper
Gas meters
Supply most at 1/4 psi may be commercial at 1-3 psi
Can supply individual occupancies or entire buildings
Regulators usually found before gas meters on high and medium pressure systems to reduce gas to 1/4 psi (except if 1-3 psi)
Peck vent releases excess gas of regulator fails
Gas shut offs
Most 1/4 turn
Use hailligen,pliers ,vice grips
Turn wing cock valve counter clockwise e
Order of preference for shutting gas
- Appliance valve
- Meter
- Interior gas riser valve ( if there is one )
- Master meter
- Head of service
- Exterior gas riser valve
- Curb valve
- street valve (only in extreme cases)
In some older high pressure gas services(con ed) the moan shut off valve will require approximately how many turns
4 1/2 to 5
Head of service valve (building service valve) just inside building where gas service enters
Most 1/4 turn
If meter(s) outside it will be before meters
Exterior gas riser valve
Located on riser outside the building before any exterior meters
1/4 turn
All external meter installations will have have riser valve installed prior to meter
If curb valve is found look for exterior riser valve
Valve may be outside if meter are installed inside building
Curb valve
Usually found on the sidewalk side of the curb
Shuts gas supply to building
Shut using gas key on apparatus
1/4 turn
Before checking see if nut is white if so it is plastic close gently
Long service on national grid may have curb valve across street from building it supplies ( ID by arrow cast into cover pointing to building it supplies) 1/4 turn
Some older curb valves are gated and may require multiple turns , if quarter does not shut gas continue to turn until resistance felt . This may occur between 7 1/2 to 15 turns .DO NOT TURN VALVE MORE THAN 15 X
Street valve (aka main or isolation valves )
Located on street side of the curb
Can look like curb valves
DO NOT OPERATED STREET VALVES EXCEPT UNDER EXTREME CIRCUMSTANCES AND ONLY UPON DIRECTION OF FD. IC AFTER CONSULT ION WITH UTILITY SUPERVISOR
Plastic pipe
Gas flowing out of plastic pipe generates static electricity which builds up on the outside and inside surface of pipe
Coming near or touching gas pipe could result in a spark that ignites the gas
Do not fold leaking pipe
FDNY lights are intrinsically safe
Non FDNY lights and thermal imaging camera are not intrinsically safe
Turn flashlights on before entering building or explosive area and do not shut off while in explosive atmosphere
If there is an indoor gas leak and you need to ventilate may you use department fans
No not intrinsically safe
Use fog stream
At a major indoor gas leak you may need to vent ,if going to vent where should you start ?
Start at upper floors if possible then work your ways own to the first floor and then out of the building
When you have major indoor gas leak you should check what exposures ?
At least 3 exposures on both sides of the occupancies with positive gas readings
Indications of outdoor leaks
Heavy gas odor in area
Opaque cloud rising from ground
Dirt and debris may be seen blowing into air from excavation (high pressure leak)
Loud roaring sound (high pressure leak)
If gas readings are obtained in electric, sewer or any other utility manhole, than we must
Check surrounding properties
If arrive at the scene of a serious gas incident prior to the arrival of the gas utility personnel and finding gas readings in the electric manhole the following info should be requested from the utility company via FDNY dispatcher
- ID of buildings be supplied electricity by involved manhole(s)
- If you detect gas at the point where electricity enters building request location of the manhole that supplies electricity to the building and any other buildings it supplies
- Utilize info to prioritizing checking buildings for presence of gas
CAN WE REMOVE SEWER MANHOLE COVERS
Yes with approval of chief
Can we remove electrical manhole covers
Yes only when requested by gas utility representative
And approved by on-scene chief
Utility company gas representative mist test cover for stray voltage first ( no stray voltage can remove)
What manholes should not be
Square or rectangular electric manhole covers
Do not pull any manhole covers if manhole fire in the area
Smoking or arcing in electrical manhole or transformer vault
If any Doubt to which manhole affected
What is the indoor action level for gas emergency
10% LEL
What is the outdoor action level
20 % LEL
FDNY will evacuate at what LEL percent
10 % if unable to reduce percent immediately
Converting percentage of LEL into percent of gas in air (used by Con Ed)
10 % LEL is equal to .50 % of gas in air
20 % LEL is equal to 1.00% of gas in air
Every 10 % the LEL raise the % of gas on air goes up .50
100 % LEL is equal to 5.00 % LEL (lower explosive limit
