Natural Gas
According to the nova ops manual on utility emergencies , what are three indications there may be a natural gas pipeline leak in the area?
Any unusual odor near the pipeline.
Dead or discolored vegetation in an otherwise green location.
Fire coming from the ground or appearing to burn above the ground.
Dirt being blown or appearing to be thrown into the air.
Water bubbling or being blown into the air at a pond, creek, or river.
A dry spot in a moist field.
B.L.E.V.E stands for?
Boiling liquid expanding vapor explosion.
Where does Carbon Monoxide come from / why does it form?
Carbon monoxide (CO) is formed by the incomplete combustion of the fossil fuels – gas, oil, coal, and wood used in boilers, engines, oil burners, gas fires, water heaters, solid fuel appliances, and open fires.
How can you tell if a downed power line is still energized?
Trick Question , You can't and shouldn't attempt to make that decision.
Often wires will appear to be de-energized because they are lying still on the ground with no movement or arching. Firefighters must approach electrical emergencies involving wires, transformers, transfer stations, etc., assuming that they are fully energized until a power company representative can confirm otherwise.
What is another common item used in the distribution of electricity commonly found on the ground?
ground based electrical transformer
Signs on the Natural Gas markers shall list what information?
Signs on the markers list the commodity transported, the name of the pipeline company and a telephone number where company representatives can always be reached.
What is the "Vapor Density" of Propane?
Is it lighter or heavier than air?
What is the proper positioning of the Engine?
The vapor density of propane is 1.56, making it heavier than air. Propane will seek low areas and accumulate until it dissipates or find an ignition source.
Engine companies shall position the apparatus prior to and upwind of the hazard area if at all possible and determine the most efficient water supply. The other responding units shall stage upwind and prior to the affected area and await an assignment from the engine company or Incident Commander.
CO is flammable , what is it about CO being flammable and its properties that makes it so dangerous?
CO is flammable and has a wide explosive range. The LEL for carbon monoxide is 12.8% and
the UEL is 74%. In terms of parts per million (ppm) carbon monoxide’s explosive range would
equate to 128,000 on the LEL and 740,000 on the UEL.
If a power line has been damaged and is hanging , nearing but not touching the ground , is it still dangerous? why?
The most hazardous conditions involving power lines are where the lines do not come in contact with the ground. The computerized system that manages the electrical grid will detect a fault and attempt to restore power. This action will instantly make the previously harmless wire deadly, creating a surge over 20,000 volts through an unsuspecting person who comes in contact with the wire.
What is the explosion risk in ground based electrical transformers due to?
If opened, they may cause an explosion due to the accumulation of flammable gases.
The common or "trade name" given to the yellow piping commonly used for Natural Gas.
The trade name for flexible gas line is corrugated stainless steel tubing or CSST /Trac Pipe or Ward Flex.
What size Propane cylinder is the most common and at what pressure does the relief valve relieve the cylinder pressure?
The most common propane incident will involve the 20 lb. cylinder (commonly used with grilling). It is estimated that there are 50 million of these cylinders in circulation. Every propane container will have at least one relief valve. The relief valve is designed to operate and release pressure when the internal pressure exceeds 250 psig
Carbon monoxide cannot be detected by the body and can only enter the body by the respiratory system. Once in the lungs and the blood stream it is absorbed into the blood and combines with the hemoglobin of the blood and excludes the needed oxygen we require for survival.
What are the symptoms of CO poisoning?
Symptoms of exposure include headache, nausea, fatigue, confusion and dizziness. Rapid transport to an appropriate treatment facility is of the utmost importance.
At an incident where a downed power line is laying on a vehicle with someone inside , what is the distance you should stay back from the vehicle?
At incidents where an individual is in a vehicle that has downed wires, stay 30 feet away from the vehicle until the power can be locked out.
When is it ok for firefighters to enter electrical vaults or substations to mitigate hazards?
Never
Firefighters should request the assistance of the electrical company immediately and focus their efforts on securing the area around the hazard to prevent civilian injuries. The power company because of their technical expertise best handles these types of emergencies.
What is the proper order or sequence for shutting off the gas utility in a leak or fire situation?
Shut Off for Natural Gas
Gas shut off valves are quarter-turn, Figure 6. The proper sequence for shutting off the utility in either a leak or fire situation is as follows:
1. At the appliance (if can be safely done).
2. At the meter.
3. At the curb box.
When mitigating a cylinder leak , is it better to have the cylinder leaking while on its side or while standing? Why?
If a container is on its side and liquid product is escaping from the relief valve the pressure in the tank is not significantly decreased. The liquid will boil off and expand to approximately 270 cubic feet of vapor for every pound of liquid released. The best objective would be to turn the tank over or upright the tank until vapor is releasing. With the liquid expansion ratio of 270:1, it is far safer to have a vapor leak than a liquid leak.
Commercial buildings have many sources of CO not found in residences.
What are some examples?
Parking garages, drive-through windows, auto repair bays, various processes, un-vented gas burners in large confined spaces, forklifts, etc. Recognizing this, NIOSH established 35 PPM as the acceptable level for commercial buildings.
Should the driver of the vehicle with the power line on it leave the vehicle? what if they are injured?
Where possible have the individual stay in the vehicle even if they are injured. If they must leave because of injuries or fire, have the victim jump clear away from the vehicle without touching the vehicle and the ground at the same time. Have them jump as far as possible, landing with both feet at the same time. Tell them to shuffle away, keeping their feet closely together to prevent step potential.
What other hazard besides the fire must be mitigated when power cables burn in a confined space?
When electrical wiring burns in a confined space, it gives off large amounts of carbon monoxide gas. Firefighters should check the nearby exposures with CO detection/monitoring equipment as this gas can travel along underground conduits and seep into nearby buildings. It can be present in sufficient amounts to result in an explosion in a distant structure. You should check and then continue to monitor the CO levels
Commercial gas meters are usually much larger and operate at higher pressures than residential meters. Turning off the wrong valve may create a more serious problem.
Which valve is the correct valve to shut off?
Commercial occupancies may have several valves. The valve to shut off is the one located prior to the regulator.
When making your approach towards the propane tank what is important to keep in mind as you choose your path?
When approaching a propane tank, do not stand or walk in the path of the relief valve; it may open at any time to relieve the tanks internal pressure.
The majority of carbon monoxide incidents occur in the winter months, and the most common source of residential CO-related poisoning is un-vented supplemental heaters. Other common sources of carbon monoxide include what?
Malfunctioning cooking appliances.
Tobacco smoke.
Clogged chimney.
Auto exhaust.
Malfunctioning water heater.
Malfunctioning oil, wood, gas, or coal furnaces.
Malfunctioning gas clothes dryer.
Wood burning fireplace, decorative fireplace, gas log burner, or any unvented space heater.
Appliances in cabins or campers, barbecue grills, lack of adequate ventilation, pool/spa heaters, and ceiling-mounted heating units.
Generators.
Malfunctioning batteries.
Relining of sewer lines.
Are/can Cable tv or telephone cable dangerous when down?
At incidents where it appears to only be cable or telephone wires down, don’t assume that these wires are not energized or hot. They may have crossed the power lines and became energized.
What is a good question to ask the power company when they tell you the power is no longer energized/live?
When advised by the power company that power is down, ask them how they determined this. Recently, an engine company arrived on the scene of a fire in a ground transformer and witnessed the door to the transformer blow off and fire was emitting about five feet into the air. After making a safety zone, they waited for the arrival of the power company before conducting any extinguishment efforts. Once the power company arrived, the power company worker advised the crew that the power was off and they could extinguish the fire. When questioning the power company worker how he had determined the power was off, he stated that traffic lights one block away were out and the circuit had blown. The engine company advised the worker that the power to those lights had been out for several hours. The worker then went back to confirm power down and realized it was still energized. Complacency and ignorance can kill you!