Don Collins: Choosing the Proper Extinguishing Agent

By Don Collins

Throughout history the means of extinguishing fires has always been to remove any component of the “Fire Triangle,” or its more recent name, “Fire Tetrahedron.” Although this certainly holds true today as well, there are so many more resources available to assist us in meeting that goal. This article discusses some of these options and also some of the limitations and potential hazards they may present.

 I recently heard of two separate incidents in which individuals put water on a grease fire; one fire was worse than the other. Neither resulted in injuries; however, one incident qualified the fire site for an unexpected kitchen remodeling. Our first reaction on hearing about these incidents might be, “What idiots!” or “Some people will never learn.” but let’s thing about it. Do we as fire service professionals share some of the blame? Should we be more aggressive in our fire prevention programs?  Some people just naturally resort to what they know, kind of like a muscle memory sort of scenario: Water is what you use to put out a fire. We know that this is not necessarily the case for every fire, certainly not for grease fires. It is much the same in our profession. We tend to go with what we are used to or what we are comfortable with–not necessarily what is appropriate for the scenario that may not be your everyday call. For example, why do we reach for the 1¾-inch speed lay when fire is blowing out of every window? Go big early!

No one knows your first-due district better than you. That being said, you should have the resources available to mitigate most, if not all, incidents that may go wrong in your district. However, do your neighboring districts or mutual-aid companies know about those special hazards that may be lurking in the shadows? They could be on a cover assignment and be first due at some point. Shouldn’t they be as prepared as you are?  Once again, it falls back to preplanning and training. I am a proponent of working smarter, not harder. Let’s train and come up with tactics and strategies now, not at 2 a.m. on a cold wintery morning when the tone goes off for that fueling facility or an incident in the rail yard. Initial response protocols and preplanning can go a long way in ensuring the successful outcome of an incident, no matter how large it may become.

Another responsibility that may be overlooked if your department has a special type of extinguishing agent is to brief all mutual-aid companies on any hazards associated with that agent. A case in point is Halotron, which displaces oxygen as it extinguishes. Because of this characteristic, all companies operating at an incident where it is in use should be informed that it is in use, and the use of personal protective equipment including self-contained breathing apparatus should be strictly enforced.

We know that the life safety of members and civilians is our primary objective; however if there is no threat to life and no real threat of fire extension, there may be situations where the application of a more appropriate extinguishing agent may be preferable to an immediate agent that happens to be on hand. In the name of property preservation, there may be scenarios where it may be beneficial to await the arrival of the proper agent for extinguishment–for example, using dry chemical to fight a fire in a computer room when a Halon extinguisher may be in an adjacent room. Sure the dry chemical did the job; however, the cleanup and decontamination of all the electronics may be more costly than the fire loss itself. 

If you respond to a petroleum tanker rollover with fire, do you have an adequate foam supply to knock the fire down? If you don’t have any foam available and you are attacking the fire with water, you need to be aware that the fuel is lighter than water and will most likely travel in the direction of the topography. Containing the running fuel should be a primary consideration, and you should request Department of Public Works or Department of Transportation resources sooner than later. Some early considerations should include the basics of life safety and exposure concerns, but not too far down on the checklist should be primary spill control down catch basins and sewers. As damaging as the effects to water supplies and the environment can be in a rural area, they can have life-threatening potential in a more urban setting if they run underground, ignite, and expose a widespread area. Tarps placed over catch basins and sewers and covered with any available speedy dry, sand, or dirt can protect against runoff.

“Foam is not foam, is not foam.” Do you have the resources to extinguish an ethanol type of fire or control the vapors of an ethanol spill?  Aqueous film-forming foam (AFFF) is only effective if the fuel is 10 percent or less ethanol, otherwise Alcohol resistant (AR)-AFFF is basically the only agent that is effective; a special polymer added to it protects the water from being absorbed by the alcohol. If you happen to have a tanker rollover and need to request mutual aid for foam, you must identify the  type of spill. AR-AFFF will work on regular gasoline and ethanol spills; AFFF is not effective on ethanol. Keep that in mind when requesting additional resources.

Also, consider that a shiny new pumper with foam capabilities may not be of much help  if the foam has to be applied from an extended distance. If you are much more than 150 feet from your foam source, you are not likely to get an adequate amount of foam onto the fire, no matter what size pump or lines you may use. Don’t look to get your money back, but realize that there are limitations and you may have to resort to buckets or barrels of foam and a portable eductor for closer proximity to the fire.

Sometimes, it may become necessary to await adequate resources before you initiate an attack, which is counter-intuitive to what most of us are accustomed to and may initially be perceived as a questionable strategy by the public. Some years ago, I attended the Advanced Flammable Liquid Firefighting School hosted by Williams and Fire Hazard Control, in Beaumont, Texas. The scenario posed was a tank fire. The initial impulse may be to cool the tank to the best of your ability; however, most tanks will have containment dykes that if they fill with water during your cooling efforts would totally defeat their purpose. Since the fuel is lighter than water, it would flow outside the containment of the dyke in case of tank failure. Another disadvantage to cooling the tank is that unless you can guarantee cooling the entire 360° of the tank, the tank is at risk for failing in the area it is not being cooled, creating a larger problem than the initial fire. They recommend not initiating an attack unless you have one and a half times the anticipated amount of foam product on hand; otherwise, you will have potentially wasted all of your time and resources by not extinguishing this fire in one attempt—a real eye-opening experience, even for veteran firefighters, if you ever get the opportunity.

Finally, I will share one story that I recall from early in my career that has always stayed with me. In the fall of 1993, 11 firefighters from Newton, Massachusetts, responded to a local industrial park, which ended up being their last call since they all suffered career-ending injuries. There was a sodium fire in a barrel. They followed protocol by using salt and soda ash to extinguish it. What they didn’t realize was that one of the shovels was damp. That slight bit of moisture reacted with the sodium and caused an explosion.  Although no one suffered fatal injuries that day, two were injured critically and endured multiple surgeries. It was certainly a dark day for the Newton Fire Department. I listened to the entire call that evening, and my heart went out to them. It was a numbing experience. 

Remember, there is no substitute for preplanning and training. Labels and placards are in place for a reason. Use the proper equipment and extinguishing agent for the conditions you are mitigating. Don’t choose them just because you always use (or grab) that equipment or agent. Learn from other incidents, even if they weren’t in your area. There is no need to reinvent the wheel. Become familiar with all of your resources, especially those you don’t use every day. Make sure companies outside of your district are familiar with any special hazards within your district; hopefully, they will share the same information with you.


Don Collins Assistant Chief/Shift Commander Massport Fire-Rescue, Logan International Airport, Boston, Massachusetts.  29 year fire service veteran, EMT-P, HazMat Tech, CISD Peer Support Counselor


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