Fire extinguishers 101
Please read this when you have time to take this information in. Read it a couple of times if necessary.
The most common type of fire extinguisher you will encounter is called a Dry Chemical A:B:E 1.0kg unit. If ever you have to use it you can be confident that it is safe with electrical, flammable liquid, paper or wood fires. You don't have to think about it, just use it. The 1.0kg unit is also the cheapest unit you will find and is sold everywhere. They are sometimes on special at $20 but they are hardly ever more than $30. By the way ABE stands for: A=Paper, wood & textile, B=Flammable liquids, paint, petrol, diesel, hot grease, etc. & C=Electrical equipment, appliances, switchboards, electric motors and other electrically powered machinery.
At $20 to $30, you should buy at least 2, preferably 4. When you get them home or in your boat or caravan remember this – always mount them between the potential source of the fire and an exit. This means that you can always escape AWAY from the fire. When you install the extinguisher, show it to your family, including children above, say, 10 years old. Show them how to unclip the unit from the wall and how to activate the trigger according to the instructions that come with the extinguisher, that is, if you are not there yourself if a fire occurs. Make sure it is mounted so that people cannot bump it as they walk past.
WHAT THEY DON'T TELL YOU
Firstly 1.0kg extinguishers (all of them) are made to a price. The dry powder under full discharge will work for only 9 seconds. That's right 9 seconds. When there is a fire you do not have time for a rehearsal. If you have a fire, immediately aim the extinguisher at the base of the flame, if you can see it. If you put the fire out in one burst, open the trigger as you may need whatever is left in the extinguisher if the flame erupts again. A one second burst should be enough to close off oxygen to the fire but you be the judge at the time. If the fire is inside a cabinet try to direct the extinguisher through ventilation holes, etc.
Now that you know how little extinguisher time you have, consider mounting two extinguishers alongside each other, one for backup.
How to improve efficiency of your fire extinguisher
The actual extinguisher chemical in your A:B:E extinguisher is a fine dry powder called ammonium phosphate, which is non-toxic. It will, however, settle into the bottom of the fire extinguisher container. If the container is left alone for years (which is likely) the powder will continue to settle. What you should do, every year or so, is take the fire extinguisher off its mount, turn it upside down and give it a shake and possibly a light tap to dislodge the settled powder. This will keep the extinguisher in tip-top condition. Also take the opportunity to check the pressure gauge needle is still in the 'green'.
Another option for you is to choose a fire extinguisher with a 1.5kg powder load. In real terms, you get an extinguisher with about twice the firefighting capacity of a 1.0kg unit. They are not that heavy that they are unwieldy and may tip the balance in your favour in a serious fire. Like 1.0kg units the 1.5kg unit is very cost effective. A 1.5kg unit gives you about 15 seconds of service. A long time.
Finally, read the advisory notes on the carton the unit comes in and rehearse in your mind now and then what you need to do in case of a fire. What do they say in the scouts? – Be Prepared!
Other interesting stuff about fire extinguishers
The active ingredient (powder) in a fire extinguisher is Mono Ammonium Phosphate (MAP). Cheap fire extinguishers mix cheap Kaolin (TALC powder) with the MAP. It is not inflammable but it is not as effective as MAP.
TALC powder is more likely to compact in the base of the extinguisher so that's why it's important to take the unit off the wall, turn it upside down and vigorously shake occasionally.
Details of discharge time. Even though a 1.0 kg will discharge for up to 9 seconds, the first 4.5 seconds is the most effective. In the case of 1.5 kg units the first 9 seconds is the most effective (15 seconds total discharge time).
ABE powder should not be used where there is an open bucket of powdered pool chlorine or bleach. These products should not be stored anywhere near potential of fire.
All fire extinguishers have an expiry date of 5 years after manufacture. Australian legislation requires that after this date, extinguishers be disposed of by replacing and emptying unit. We are reluctant to advise you to do this, as an old fire extinguisher can be an ok secondary unit (after you have new primary units).
Do not throw out the old extinguisher without discharging it to empty. You can have some fun!
If you have a garden – even a grass lawn – you can gain some practice using a fire extinguisher by giving it a good shake and then spraying the powder over your flowers or vegetables. You can even get an idea of how to most effectively aim the unit for the most effective coverage (in the event that you need to aim an extinguisher in a real fire).
The MAP happens to be the world's most popular fertiliser, so hose it in afterwards!