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The right fire extinguisher and how to use it.

Are you prepared for a grease fire in your kitchen? Do you know what to do if flames shoot out from under your car hood? Do you have a fire extinguisher that's suited to the fire at hand? Is it charged and in good working condition? Do you know how to use it?

Answering yes to all these questions can mean the difference between minor fire damage and disaster. Take the right steps and you may be able to at least contain a small fire until firefighters arrive. (See the box on page 128 for facts you should know about fighting fires.)

Classifying three types of fire

To pick the right extinguisher for your kitchen, workshop, car, media center, or home computer workspace, you must first know how fires are classified. Applying the wrong extinguishing agent can spread the fire or endanger your life.

For example, water is a good choice for putting out a wood or paper blaze, but it will spread a grease fire. Spray water on an electrical fire and you risk electrocution. The chart on page 122 explains the properties of various extinguishing agents, and which types of fires they are meant to fight.

Underwriters Laboratories (UL) classifies three kinds of household fires:

Class A fires involve common solid combustibles: wood, paper, fabric, rubber, and plastics. Water quenches such blazes through cooling action. Other agents work by interfering with combustion.

Class B fires are fueled by the vapor-air mixture that forms above flammable liquids such as grease, oil, gasoline, tar, paints, and cleaning solvents. To put out the flames, you must interfere with com

bustion or cut off the oxygen supply.

Class C fires are sparked by electricity but feed on class A or B materials. This type of fire requires a nonconductive extinguishing agent to put out the flames.

What puts out each type of fire

Dry chemical, carbon dioxide (CO.sub.2), and halon are the three agents most commonly found in household and automotive extinguishers.

Dry chemical extinguishers. These units have been around the longest and have a proven record. Two types are suitable for home use: ammonium phosphate, universally regarded as the best multipurpose extinguishing agent, bears an ABC rating, meaning it puts out all three classes of fire; sodium bicarbonate (common baking soda) in combination with flowing and drying agents bears a BC rating and is more effective for extinguishing class B fires. Sodium bicarbonate extinguishers are especially well suited for the kitchen, which is where three out of four household fires begin.

The drawback of dry chemical extinguishers is the mess they leave behind. All use pressurized gas to expel the powdery agent, covering everything in their path with a nonflammable coating. The residue can be easily vacuumed and wiped from washable kitchen surfaces, but it's harder to remove from carpeting and upholstery, and may ruin electronic equipment. Of the two dry chemical mixtures, ammonium phosphate is the more corrosive and tends to harden on heated surfaces. The other two types of household extinguishing agents are gaseous.

Carbon dioxide (CO.sub.2) extinguishers. Carbon dioxide gas pressurized to a liquid state is utterly clean, environmentally safe, and nonconductive. It extinguishes class B and C fires by cutting off oxygen and smothering them.

But there are disadvantages to using CO.sub.2 instead of halon. Canisters for CO.sub.2 require much heavier casing, for one thing; a CO.sub.2 extinguisher weighs half again as much as a same-size halon unit. And CO.sub.2 is about half as effective as halon for extinguishing class B fires. It also has a shorte "throwing distance" than halon; you have to be closer to a fire to fight it with CO.sub.2.

Salespeople may try to dissuade you from buying CO.sub.2 by warning of the dangers of oxygen depletion, as well as of thermal shock to electronic equipment. Usually, neither problem is serious with the quantities of CO.sub.2 used in fighting household fires; flames are far more likely to damage your equipment than thermal shock. CO.sub.2 is extremely cold, so be careful not to touch the end of the extinguisher's hose, or get in the way of the gas cloud.

Halon extinguishers. Halon, developed in the 1970s to protect computers, was soon adopted for protecting airplanes and, ultimately, homes. The heaviest of the gaseous agents, halon chemically interrupts combustion to extinguish class B and C fires. It's especially effective for putting out fires in cramped, enclosed spaces,

such as car or boat engines.

Larger units (9-pound capacity and over) contain enough halon to earn a rating (though a low one) for class A fires as well. (Halon puts out these fires by cutting off air supply.) If a smaller halon extinguisher is used on a class A fire, the flames may be temporarily stifled, but the blaze is likely to rekindle when tbe halon disperses.

Most of these extinguishers use halon 1211 as the extinguishing agent and nitrogen as the expellant; "blended" units use halon 1301 as the expellant. Although some manufacturers claim blended units are more effective, independent testing has failed to prove this claim. Also, blended units may not operate properly in extreme temperatures.

Halon can be harmful if inhaled; however, quantities contained in household extinguishers don't usually pose a health risk. The gas is most dangerous for infants, elderly people, and those with respiratory problems.

Halon becomes more dangerous under heated conditions; evacuate the fire area as soon as possible.

Halon extinguishers have another very serious drawback. Scientific evidence has linked halon, along with chlorofluorocarbons (CFCs), to the destruction of the earth's ozone layer (see page 129).

What the label tells you

Fire extinguishers are rated according to standards established by Underwriters Laboratories. Ratings assigned by UL and other authorized testing laboratories, such as Factory Mutual Research Corporation, indicate how effective a given extinguisher is in fighting each type of fire. Labels display symbols for the specific class or classes of fire the extinguishing agent can fight. A slash through a symbol means that it's hazardous to use the agent against that class of fire.

Fire extinguishers are also rated with a number indicating the size of the fire they can put out. For example, a unit rated "1A" should put out a blazing stack of 50 pieces of 20-inch-long 2-by-2s. An extinguisher with a "2A" rating should put out approximately twice as big a fire as the 1A unit.

A unit rated "1B" should snuff 3-1/4 gallons of flammable liquid burning in a 2-1/2-square-foot pan.

A "C" rating means the agent is nonconductive and therefore safe to use on electrical fires. Class C designations are never preceded by a number.

In addition to a UL or other laboratory rating, a fire extinguisher also has operating instructions (visual as well as written). These tell where to position yourself relative to the fire, and give specific step-bystep directions. Familiarize yourself with these directions.

Disposable fire extinguishers: some cautions

The biggest news in extinguishers is the boom in sales of disposable units, most filled with halon. Many of these units aren't rated by an approved testing lab. Those that are seldom earn very high ratings, and almost none qualify for an all-purpose ABC rating. Many disposable units lack gauges, so there's no way to tell whether they're fully charged. All disposable units must be replaced after a single use, even a minor one.

Perhaps the most significant problem with these units is recovery of unused halon. Several manufacturers have set up recovery and recycling programs for these extinguishers, but most units are carelessly discarded. To encourage the move toward responsible recovery, the EPA recommends that consumers who have partially expelled disposable halon units return them to the manufacturer with a request that the halon be recovered.

Things to think about before you shop

First and foremost, don't invest in a fire extinguisher unless it's listed by an independent testing laboratory, such as UL or Factory Mutual Research.

To select a suitable extinguisher, make an assessment of the hazards in your household. Evaluate portability of the unit; ease of removing it from its mount; ease of handling and operation; and capacity, range, and firing time.

How hefty is your model? Remember that weight designations refer to capacity rather than to the gross weight of a fully charged extinguisher. For example, a 5pound dry-chemical extinguisher actually weighs about 8 pounds, a 5-pound halon unit can weigh 9 pounds, and a 5-pound CO.sub.2 unit weighs about 15 pounds. All household extinguishers of 10-pound capacity or less will discharge completely within a maximum of 30 seconds.

Consider who's going to be using the extinguisher: is the extra power worth the extra weight?

Although UL ratings of same-size, sameagent extinguishers are generally close, they do vary somewhat from brand to brand, so shop around. If you have any questions, call your fire department.

Most of the extinguishers offered for household use are the stored-pressure variety. These combine the extinguishing agent and expellant in a single container. Most have pressure gauges (dial-andpointer types are easiest to read) that indicate whether the unit is fully charged. Because they can be easily recharged, they are an economical choice for home use. Rechargeable units are superior from an environmental standpoint as well. Prices vary widely, and dry chemical units are often discounted.

Choosing the units for your home

Ideally, every household should have a sodium bicarbonate extinguisher in the kitchen. At the very least, keep a box of baking soda handy. (But remember that while sodium bicarbonate is one of the best agents against grease fires, it's not effective against class A or C fires.)

For all-around protection, have a dry chemical (ammonium phospbate-type) extinguisher on every floor of your house. This is the most versatile unit and the least expensive to buy and maintain. Ammonium phosphate extinguishers are also excellent for garage and workshop fires. And of all three commercial extinguishing agents, dry chemical is the most effective in outdoor and windy situations.

If you are particularly concerned about protecting prized stereo or computer equipment, halon is the most effective weapon. An alternative without the environmental questions is CO.sub.2.

If you do buy a halon extinguisher, target the applications that really demand it (see chart, page 122). We suggest you avoid blended and disposable halon units altogether. With 1-1/4-pound rechargeable halon units readily available, there seems little point in buying a disposable unit. Once you bring your extinguishers home, install them in plain view, near an escape route and well away from potential fire hazards. Finally, make sure all family members know what to do if fire strikes and that teenagers and adults know how to operate the extinguishers.

Maintaining your fire extinguisher

Keeping your unit in good working order is as important as having the right one on hand. If it has been tampered with or even slightly used, take it in for service. Local distributors usually handle inspection, servicing, recovery, and recharging. To find a fully licensed dealer, look in the yellow pages under Fire Extinguishers.

In general, dry chemical can cake up in the canister. When you check the pressure gauge, it's a good idea to turn the unit upside-down and shake it to fluff up the chemical; replace dry chemical every six years. Halon and CO.sub.2 can leak out of the unit, so it's a good idea to have these extinguishers weighed annually. Plan on paying a $10 service charge on top of any cost for replacing extinguishing agents: about $1.50 a pound for dry chemical, $1 for CO.sub.2, $10 for halon. The cost of recharging smaller units may be about the same as the cost of replacement. At home, follow the manufacturer's maintenance instructions. Check the pressure gauge monthly to make sure the unit is fully charged. If it has a pie-shaped dialand-pointer gauge, the pointer should register well within the green wedge. What's ahead for halon extinguishers?

As a fire-fighting agent, halon was a breakthrough discovery. Now, however, scientific evidence is mounting that it, along with chlorofluorocarbons (CFCs), is also damaging the ozone layer-the 3-millimeter-thick "shield" that surrounds the earth, 15 miles above the surface, and filters out dangerous ultraviolet (UV) radiation.

For purchasers of fire extinguishers, the largest problem remains safe and proper disposal of partly used halon units. But recycling opportunities are expanding, and several extinguisher manufacturers have begun encouraging distributors to promote CO.sub.2 over halon for home use.

While CFCs have received more media attention and are more significant by volume, balons are more potent ozone depleters (halon 1301 is 11.4 times more destructive than the most damaging of the CFCs). In terms of destructive potential, halons account for as much as 14 percent of U.S. production of ozonedepleting chemicals.

In 1987, the United Nations sponsored a conference in Montreal to discuss the problem. Since then, 45 of the participating nations have signed an international treaty calling for a 20 percent cut in CFC production over 1986 levels by 1993. The Montreal protocol went into effect in January 1989, establishing an additional 30 percent cut by 1998 and a freeze on halon production at 1986 levels by 1992. Many scientists, environmental groups, and the EPA fear that such cutbacks may not be enough to stop the breakdown of the ozone layer. New findings suggest that the problem in certain seasons and latitudes may be bigger than predicted. In light of this evidence, the EPA is moving to phase out production and use of ozonedestroying chemicals worldwide.

When to fight a fire: words of caution

Just because you have an extinguisher doesn't mean you should try to put out every fire. Stand and fight only if all of the following statements, taken from the National Fire Protection Association's recommended procedures, are true:

* Everyone is leaving the house and the fire department is being called.

* The fire is small and confined to the area where it started (wastebasket, cushion, small appliance, etc.).

* You can fight the fire with your back to an escape route.

* Your extinguisher is rated for the type of fire you are fighting, and it is in good working condition.

* You know how to operate the extinguisher.
COPYRIGHT 1989 Sunset Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Date:Mar 1, 1989
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