Tuesday, June 26, 2012

Fire Extinguisher Selection

A client sent a picture to me today that started me thinking about fire extinguishers. It was a picture taken at his facility of a welding rig trailer with a fire extinguisher attached to the center of the trailer tongue. Sounds good, right? I’m sure the welder knew that having a fire extinguisher around his operation was a god idea, and this one was right out in the open where it could be easily seen. The problem was that the welder was either worried about the extinguisher being stolen, or simply falling off, so he attached it to the trailer with zip ties. He used two of those big, beefy models that probably have a breaking strength of about 200 pounds. So, unless you happen to have a pair of diagonal cutting pliers in your hand when the fire breaks out, the extinguisher is effectively inaccessible, despite being right out in the open.
   Of course, fire prevention is a much better option than fire fighting, even for professionals, but the OSHA standards still dictate that fire extinguishers must be present on a variety of jobsites, and for many tasks. It’s even a great idea to have one (or more) at home, for about the same reason it’s a great idea to wear your seatbelt in the car. The first step, then, is to pick the right type of extinguisher. To do that, the workplace has to be evaluated to determine what kinds of fires may be present. The types of combustibles will dictate the types of fire extinguishers that are appropriate. Using the wrong type of extinguisher for a given fire could be merely ineffective, or it could make matters much worse. If you don’t believe that, try spraying an air-pressurized water (APW) extinguisher on a raging grease fire. (Okay, that was just a thought experiment; don’t really try that.) If there is any doubt as to what exactly might catch on fire, consult the SDS or MSDS, and seek help if you’re still not sure.
    Class A fires are ordinary combustibles, such as wood and paper. Class B fires are flammable liquids (think oil or gasoline.) Class C fires involve energized electrical equipment (that APW extinguisher we mentioned earlier is starting to seem a little limited!) And Class D fires are combustible metals such as sodium, magnesium, and aluminum. There is also a fairly recently designated Class K fire, involving cooking oils or fats. This would technically be a subset of Class B, but there are some control techniques that apply to larger kitchens that warrant their own class.
   To choose the right extinguisher, then, one only has to match up the fire type with the extinguisher type; it will be printed right on the label. What if the label is worn off or illegible? Then it’s time for a new extinguisher! Extinguishers may be effective on more than one type of fire. As an example, one of the most common types of extinguishers is the dry chemical, Class ABC extinguisher. It is usable on all three common types of fires.
   Once the extinguisher is chosen, then it should be mounted in a designated place, and kept accessible. That means we shouldn’t pile stuff up in front of it, obscure it, lock it away from people, or tie wrap it to a structural member! If people cannot get to the extinguisher, there is no point in having it. (Oh, and they need to be trained on how to use it properly.)
   That should be enough to start out on, and I’ll look at extinguisher capacity, inspection, and use in a later post. If you have any good fire extinguisher photos (that don't incriminate anyone) share them on our Facebook page.


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