Flammable Liquid Fires Put Thinking Ahead of Fast Action
departments
The Volunteers Corner
A fundamental error made at sizable flammable liquid fires is the immediate application of foam before making a determination of the amount of foam required.
Fire fighters are only human when they react to flaming petroleum product or polar solvent incident by starting an attack with foam lines at once. However, they may be setting the scene for an even larger and more hazardous problem.
Remember, if you have not extinguished the fire by the time your foam supply runs out, the flames that remain will start burning the applied foam and will gradually spread throughout the flammable liquid area. Now you face the original extinguishment problem, but have that much less foam to handle the situation.
Price of waste: By asking members of fire departments attending training sessions we have conducted in Connecticut, we have found that four 5-gallon cans of foam concentrate is about as much as you can expect to be on an engine. Here and there, you will find an engine equipped for greater foam capacity, but they are few and far between. So let’s say that the first-in engine company immediately applies its 20 gallons of foam concentrate and the second-in engine company does the same. However, the blazing highway tanker requires the application of at least 130 gallons of foam concentrate for extinguishment.
While you wait for more foam to arrive on the scene, the remaining fire burns off your original application of 40 gallons of foam concentrate and you still need 130 gallons of foam liquid. However, the total amount needed for this incident has now jumped to 170 gallons because you wasted the first 40 gallons. In some areas, that additional foam concentrate is hard to come by and even if it is available, it may have to come from too great a distance and take too long in transit to be of any use.
That’s why it is important to estimate how much foam is needed to extinguish a flammable liquid fire immediately. A delay of foam application for a few minutes can give other apparatus time to arrive with enough additional foam to extinguish the fire—and thereby minimize your problem.
Protect exposures: If you don’t have enough foam for an immediate and successful attack, your first objective becomes the protection of exposures. We are all aware of the need to protect buildings that are exposed to fire. You also will be aware of endangered motor vehicles in the area.
At a bulk storage plant, we’re aware of the other tanks that are exposed to the fire, but what about the gasoline tanker with a ruptured compartment and the railroad tank car with other derailed tank cars around it? In the case of the highway tanker, the immediate exposures are the other compartments of the tanker. For the railroad tank car, the immediate exposures are the burning tank car and those next to it.
Use master streams—if the water is available—to protect these hazardous exposures. Remember, deluge sets can be set up and then left unmanned for safety reasons. Always expect an explosion and allow as few men as possible in the immediate area only as long as absolutely necessary and then none at all when there are indications that your efforts are not cooling the tanks.
In an area where there is not enough water for adequate cooling and your failure is ordained, evacuation of all personnel is mandatory. Obviously, civilians have already been removed from the area.
Determine what’s burning: In addition to sizing up the general situation, the first-in officer should make every effort to identify the product that is burning. Binoculars can be a vital safeguard by making it possible to read a DOT placard at a safer distance. The placard color and design at least indicate the category of any hazardous material and the number on the placard keys you to basic information about the product in the DOT guidebook that should be aboard every apparatus. The number identifies the product and refers you to a page in the guidebook with basic information on handling fire, spill and health incidents.
Identification of the product is necessary to determine the type of foam needed for extinguishment. Petroleum product fires can be extinguished with protein, fluoroprotein, high-expansion and AFFF foams. More and more fire departments are putting AFFF on their apparatus because it will extinguish a fire in about half the time of the other foams mentioned and only about half as much foam concentrate is needed.
The major problem is when polar solvents—or miscible liquids—which mix readily with water, are burning. For polar solvents, or alcohol-type liquids, an alcoholtype foam is required. Ordinary foam will be dissolved as fast as it is applied to polar solvents. If all you have is AFFF, apply it at about a 10 percent concentration—or at the highest ratio your eductor will permit. It isn’t the best answer, but it will have a desirable effect.
The answer, of course, is to also carry alcohol-type foam—available in both protein and AFFF foams. Storage space on the apparatus is the drawback to doing this.
You should make every effort to approach a flammable liquid fire—or even a spill or leak—from windward to avoid vapors that can ignite any second. You also should approach from the high side so that your apparatus does not get trapped by a flowing spill and become part of the problem when ignition occurs. Just because there is no product spill on your arrival, that is no assurance that a spill will not occur before you have the incident under control.
