By Daniel P. Sheridan
During my fire service career, I must have responded to thousands of natural gas leak emergencies, some with devastating consequences. The worst one, prior to our most recent disaster in Harlem—where eight lives were lost and which destroyed two five-story tenements—was in Harlem as well.
Sometime in the early 1990s, we responded to a gas explosion in an 11-story type I high-rise fireproof multiple dwelling (HRFPMD). The building was a senior citizens housing complex; not exactly a nursing home but rather a home that served the needs of the elderly.
Gas leaks in these HRFPMDs are very routine occurrences for my department. Generally speaking, people live very close to each other in these buildings, so if there is a gas leak, someone will smell the Mercaptan that the gas company uses as an odorant and calls the gas company and/or the fire department. This particular day, the occupants of the building were on a day trip to Atlantic City. The building was almost empty except for one unfortunate soul that didn’t make the trip that day and stayed back. People were saying that it was a miracle that there was only one fatality. The reality is that if the building was fully occupied, someone would have detected the gas and called the fire department.
Gas has the following properties:
- It is composed mainly of methane but also contains ethane, propane, and nitrogen.
- It is colorless.
- It is odorless (Mercaptan is added to give gas the rotten egg odor).
- It is lighter than air.
- It has an explosive range of five to 15 percent.
- It has an ignition temperature of 1,163°F.
- It is nontoxic.
- It is an asphyxiate.
Because of the heavy call volume concerning gas leaks, there can be a tendency to become complacent. I know at times I can be guilty of this myself. One of the ways to combat this is to make sure that we are always in our full personal protective equipment when responding to these calls. We need to remain constantly vigilant and resist the urge to fall into the complacency trap.
I recall an incident in a six-story type III multiple dwelling; it started out very routine. We located the source of the gas leak in an apartment on the third floor and entered the apartment to find that it was coming from the stove. On further investigation, we discovered that the occupants were stealing gas by rigging a piece of tubing bypassing the meter. Things started unraveling pretty quickly; the gas started spewing out of the tube and somehow ignited. Our gas emergency now had become a fire.
It was fortunate that the gas had ignited because it saved us from having a major gas leak in a confined space. A hoseline was then required to keep the fire from spreading. Once the gas was shut down at the meter in the basement, we extinguished the fire. It is extremely important to remember that if gas is leaking and it’s on fire, DO NOT EXTINGUISH IT.
Many of the older buildings in New York City still have the old gas pipes that were used for lighting and are now either capped or have paraffin to close the openings. Recently, while dining in an old restaurant in Greenwhich Village with my uncle, he pointed out the old light fixtures and asked me about them (photo 1). I explained what they were and that they leak frequently. Sometimes, we get called for a gas leak in these older buildings and the firefighters check the usual culprits: the stove or the dryer. After finding that they are not the cause, we usually find an old fixture with a slight leak.
(1) Photo by author.
If we don’t get an exact apartment or location, it can be extremely frustrating trying to locate the source. When I first came on the department, I don’t recall having any meters available. We would get to the area where we thought the leak may be and tried to track down the leak using the only tool available: our sense of smell. We would literally put our noses up to the cracks in the door and try to determine if that was the source. Shortly thereafter, I remember the department issuing every battalion car a meter that sensed gas. Today, every ladder company has one as well as a meter that also detects a percentage of the lower explosive level (LEL).
Picture yourself looking at your car and thinking that you need air in your tires. Unless you put an air pressure gauge on the stem and measure the pressure in the tires, you can, at best, guess. The same holds true with gas; the only accurate way to measure the gas is by taking a reading with a meter that measures the percentage of the LEL.
If your department doesn’t have a meter that is capable of determining the LEL, get one. Gas leaks are like fires in how people report them. Think about it; in a multiple dwelling, where people live practically on top of one another, anytime someone burns a pot or has any type of smoke condition, you will get a few calls to the dispatcher. Conversely, in a private dwelling, if no one is home, we usually don’t get the call until the fire or smoke makes itself known by either venting out the windows or some other opening. The same thing is true with gas, if someone smells gas in a multiple dwelling and no one is home, the neighbors will smell the Mercaptan and call someone, be it the fire department or gas company. If no one is home in a private dwelling and there is a gas leak, who and when will someone call the fire department?
The worse-case scenario is a gas leak in a private dwelling where the gas is filling up the house. Someone calls the fire department. We arrive, we do what we always do: position our trucks in front of the building. The house is now loaded with gas and looking for a source of ignition. We get to the front door and find no one home (WE DO NOT EVER RING THE BELL!). The door is now forced and we introduce air into a too rich to ignite gas environment. The levels drop now with the influx of fresh air to an acceptable level (five to 15 percent), and there is an ignition source.
Think of a gas leak as you would a potential backdraft. No firefighters would ever intentionally do something that would cause a backdraft; we would heed the warning signs. If we pulled up to a strip mall at 0200 hours and encounter backdraft conditions, we would adjust our strategy and tactics accordingly to prevent the backdraft. The same should hold true with a gas leak. If we had a meter that detected the levels of gas, we would know exactly what may lie ahead. For example, if the meter pegs out at 100 percent, we would know that the area is either too rich or just right for an explosion. This would be the time to form a strategy to prevent the explosion. We would haveq to take the appropriate measures, which may include the following:
- Our number-one priority is to try and shut the gas as close to the source as possible.
- We do not want to cause any sparks. Static electricity can even be a problem.
- If your flashlight is not intrinsically safe, it may cause a spark.
- If the electricity needs to be cut, do so outside the building. Also make sure there is no emergency backup power; many people today have generators that kick on automatically.
- Vent vertically, but keep in mind that if the area is too rich too burn, we may be bringing the levels down.
- A fog hoseline should be stretched and can be used to vent. (Gas is explosive when it is in a confined space. If you have a gas leak outside, there is no need to try and disperse the gas with a fog hoseline. You may make the situation worse by bringing the levels down. You should stretch a hoseline to protect exposures.)
Gas leaks may become a more common occurrence in the future as more people are becoming gas customers. People are moving away from oil heat and turning to gas because it’s clean, more efficient, and cheaper. Fracking is increasing and making the supply more readily available. As the amount of gas use increases, call volumes and emergencies will increase accordingly. Stay safe, and don’t become complacent.
Photo found on Wikimedia Commons courtesy of Highway Patrol Images.
Daniel P. Sheridan is a 25-year veteran of the Fire Department of New York and a covering battalion chief assigned to Division 6 in the South Bronx. He is a national instructor II and a member of the FDNY IMT. He is a consultant for www.mutual-aid.org.
