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Friday, February 19, 2010

A Fire extinguisher

Fire and the Prepper

Fire is a disaster that can strike us easily. It is much more likely that we will deal with a fire in our lifetime than that we will have to face TEOTWAWKI. In the Western USA, we also often live in areas subject to wildland fires. So we do have to plan for that also. Some quick notes on fire extinguishers in this piece. A future article will provide very basic coverage of wildland fires and your family's prepping measures.

We all know enough about fire extinguishers to buy a dry chemical extinguisher. Because all the excellent public information programs tell us that they can be used on all types of fires. But how much capacity do we need? How many for our houses? What about those carbon dioxide and halon-type units?

A review. For fire to happen, there must be fuel, heat, oxygen and a self-sustaining chemical reaction between the former three . For our purposes, there are three classes of fires. Type A is fire in paper, wood, couches, and rubber or the like. Extinguishers rated to work on A use this metric to measure effectiveness: each numbered increment represents the extinguishing power of 1.25 gallons of water; so a 5A would equal 6.25 ga of water. Water breaks the heat side of the tetrahedron and the steam from application helps break the oxygen side of the tetrahedron.

Type B is in flammable liquids. The metric for this rating is that each B increment represents one square foot of burning fuel that the layperson can extinguish. So a 40-B would extinguish 40 square feet of burning liquid. Dry chemical B extinguishers attacks the chemical reaction that supports the burning process. Foam type extinguishers cut off the oxygen and some provide attack on the heat also.

Water fog, or class AB or B rated foam, can be used on a class B fire, but for the prepper this will mean having a charged hose line with a good adjustable nozzle if water fog is used.

Type C indicates fire involving energized electrical equipment. This rating on an extinguisher just means that the extinguishing agent does not conduct electricity.

For the prepper, our agent choices are: water, dry chemical, gas type, and portable foam units.

Pressurized water units are venerable performers on A class fires as they are easy for laypersons to use. Just watch out for energized electricity around them or any use on class B fires! And follow manufacturer's directions to enable them to survive Montana Winters.

Dry chemical units work well but have a few downsides: the powdery mess which can get into electronic equipment and other inconvenient places, the cloud of powder can obscure the firefighter's vision, and the agent melts onto hot surfaces, forming a very tenacious film, so cleanup is hard. But these agents work well and are versatile. Better a hard cleanup than a lost home tragedy.

Carbon dioxide, and halon-types, extinguish B and C fires with no mess and work very well for fires in enclosed areas, but do have some downsides: carbon dioxide units are notoriously heavy so can be hard to bring to bear, if a class B fire is in an open area, there is a high probability of reignition as oxygen reaches the fire again, these agents are nearly useless on class A fires, and these agents displace air so the prepper in an enclosed space who is using one of the gas extinguishers could be overcome from lack of oxygen. Plus, these units cost much more than dry chemical-based units, often easily by a factor of three.

One note here, there are small halon-type units available that are about the size of a large spray can. Maybe keep one near your computer or entertainment center for quick knockdown of electrical fire? Cold Fire(r) is one brand that is easily available at Costco and other major retailers for a good price.

Portable foam units work well, but make sure that your unit is rated for AB, not just A. The downside of these units is that they are technique sensitive. These units cost significantly more than dry chemical-based units but less than gas-based extinguishers.

The OSHA “gold standard” is a 3-A 40-BC unit for business use. the small 1-A 10-BC units that fit in the little brackets on the wall work for small spaces or for your car or SUV. If you store large amounts of flammable liquids , you might consider buying one of the large, wheeled units. These units can be surprisingly easy to deploy and feature good ratings of 100-BC and above.

Plan your placement of extinguishers carefully. An extinguisher is useless if you might have to go through the fire to access the extinguisher. For example, have extinguishers available in rooms on both sides of the kitchen so you can access a unit no matter where you are in the house. In a shop, have a unit available at the entrance as well as in high risk areas in the shop.

Whatever capacity you choose, don't forget that you have to be able to physically haul it and deploy it. A few 4-A 80-BC units in your retreat? Can all family or group members handle them effectively? Or would it be better to buy a few more smaller units that are more generally deployable? Place units near high fire risk areas. So near the kitchen, woodstove, fuel storage area, shop, barn, etc. Also consider having a unit available in your sleeping area so you can start an attack, or facilitate you and your family's escape quickly.

Here are some useful links to learn more:

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1 comment:

  1. Love the blog title, thought Id just point out that haylon is actually banned in the UK now and we use a FE36 replacement gas.