By Daniel Sheridan
In November 2011, five firefighters were inside a home in Pennsauken, New Jersey,, when there was a major gas explosion. The firefighters were all taken to Cooper University Hospital. The home on the 2500 block of 42nd Street was occupied, but no homeowners were injured in the blast. The fire started around 6:20 a.m. The home was severely damaged.
I received this story via my Blackberry one day last year, but it’s an example of a type of event firefighters seem to be seeing more and more. I am not sure if these incidents are actually happening more often or if we are finding out about them when they happen because we live in an age of instantaneous information. I have been to literally thousands of gas leak emergencies in my career–99.9 percent of the time we find the source of the gas leak and contain it by shutting off the petcock valve at either the stove, the meter in the apartment, or in the basement. In the worst case scenario, we have to shut down the gas service to the whole building.
In New York City, there are buildings in the older parts of the city that still have the piping for the old gas lamps. Sometimes the plugs get worn and fall out and we receive a call for an odor of gas. The firefighters naturally assume that is the stove and don’t find the leak. After 15 frustrating minutes of being unable to find the leak, they have already opened the windows and the odor dissipates. Generally, the firefighters will leave and tell the citizens to call back if the odor comes back. Hopefully either the occupant or the firefighters will have notified the local gas company and they will come with more sophisticated meters and better knowledge to locate the leak.
The other night we responded to a gas leak in an older building. The truck company went to the location of the reported leak and found that the stove was indeed leaking. These types of calls are so routine that I really don’t give them much thought, I do instinctively know how dangerous these can turn out to be, but I don’t get too excited about them either unless we can’t shut the gas off. The local gas company showed up on scene (it’s very rare for them to show up while we are actually there). The only time that I normally see them is when they get call first and they need our help for forcible entry.
I stayed in the street in front of the building, I let the dispatcher know that we had a gas leak in an apartment on the third floor and that the gas company was already on the scene. The lieutenant of the truck company let me know that he was having trouble finding the shutoff for the gas in the apartment. This worried me a little bit. I had all the companies remain on the scene. I don’t like having an uncontrolled gas leak in a fully occupied building. I conferred with the gas company representative and told him that we could not shut the gas off in the apartment. He let me know that the shutoff was in the basement; he had been to this location before.
The truck company went to the basement and needed to force entry into a few doors before finally locating the shutoff. When I came on the fire department, we responded to gas leaks on a daily basis, and were surrounded by project-type buildings that each contained more than one hundred apartments. We didn’t have any meters back then, so we relied literally on our sense of smell, putting our noses up to the cracks in the doors and seeing where we thought the odor was the strongest. At some point, the battalion car obtained a meter that didn’t have any gauges on it but rather emitted a steady beeping noise, the idea being that the intensity of the beeping would increase the closer we got to the source of the leak. Finally, every truck company got one and we still use them today.
Yes, the meters are good– they help us locate the leak–but the meter doesn’t tell us how much gas is leaking. The nice thing about getting a call for a gas leak in a multiple dwelling is that with so many people living in close quarters, they usually notice it pretty quickly and notify the fire department and/or the local gas company. We normally get there pretty quickly and mitigate the situation without any consequences. Once we turn off the gas, we NEVER turn it back on. We notify the gas company and a representative come and resolve the problem.
The problem is when the gas leaks for a long time and it goes unnoticed. This usually happens in private dwellings. In one of the outer boroughs we had a few instances where some houses blew up because of leaking gas. Remember that the pipes that are carrying the gas may be more than a hundred years old. Sometimes contractors doing work rupture pipes or some other event occurs that compromises the piping. The local utility company thought that the situation was so dangerous that they donated a meter that is capable of actually measuring the percentage of gas in the atmosphere to every truck company in our department.
I remember a gas leak that we responded to in a 14-story, fire-resistive, multiple dwelling that destroyed the top three floors of the building. Unbelievably, we only had one fatality. The destruction was such that it looked as if a bomb had been dropped from the sky to the top of the building. The reason for only having the one fatality was that the occupants of the building were all senior citizens and were on a day trip to Atlantic City. The flip side of that coin is that is that if they had all been home, we would almost certainly have been called much earlier. I have seen roach bombs, normally one can of aerosol, destroy an entire apartment.
We now have the ability to know now the exact percentage of gas in a building. Natural gas has an odorant placed in it from the local gas company, but if they didn’t put it in we would never know when it was leaking. Gas has an explosive range of between five and 15 percent. If it is less than that it is too lean to explode, too rich and you have the same situation. The problem is when it is between those two numbers. We have a meter that reads a percentage of the lower explosive limit (LEL). For example, if the meter reads 20 we know that it is at the 1 percent level. If it is 80 percent, we are at the 4 percent level. The local gas company wants us to evacuate at the 80 percent reading.
I think every company that responds to a reported gas leak should have a meter that can read the percentage of gas in the atmosphere. I still can’t believe it when I call to an officer and ask him what the meter is reading and he responds back to me that he left the meter on the truck. More often than not we will not have a problem, but if you are responding to an unoccupied house or apartment and someone tells you that they have been smelling gas for a while, YOU MUST TAKE A READING BEFORE ENTERING. Engine companies should be on a hydrant and be ready to stretch a line. Remember, too, that if the atmosphere is too rich and you open a window you may bring the levels down back into the explosive range. I realize that these are routine emergencies, but stay alert, and be safe.
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.