Fire extinguishers, for your reference.

[goldnugget]

Hello everyone,

As I started to discuss a little of my firefighing knowledge and safety precautions on the gas hotwater thread, I thought I would share SOME OF WHAT I know about Fire Extinguishers, how to use them, storage and signs to look out for to make sure it will most likely work when you need it.

First things first...what sort?

Well there is well and truely an assortment of fire extinugishers out there, and each has their own characteristics and specific type of use they are designed for. I will primarily discuss the most common type of extinguisher available to most people which is the Dry Chem Powder (DCP) type extinguisher. These are generally easy to identify without looking at the label, they will be a red cylinder with a white band around it near the top (some older cyclinders may not have the white band or the band has deteriorated over time).

DCP extinguishers are available in an assortment of sizes, commonly 1kg through to 9kg (each manufacturer has their own variation eg 1.3 kg, 2.3 kg, 4.5kg and 9kg).

The most common that you as a general (non commercial) citizen will find are 1kg capacity (sometimes 2kg) from places such as Bunnings, Autopro etc (and sometimes at Aldi), and also from Safety Shops (may stock larger units).

What to look for in an extinguisher?

You are better off getting an extinguisher with a metal head, it may cost a few bucks more but the plastic head units tend to leak out propellant (diferent expanding properties) and also are more suseptable to damage (accidently snapping it while loading and unloading gear)

I have seen cheap aerosol can type extinguishers for sale..I would recomend staying clear of these due to lack of capacity and they dont have a gauge.

This brings me to the next point being the gauge..generaly there is a red zone to the left (recharge), a green zone in the middle (charged), and a red zone on the right (overcharge), when buying an extinguisher make sure the gauge is sittin happily in the middle of the green zone or slightly higher (just in the overcharge area is fine too) but if the needle points way into the overcharge zone and beyond indicates either a faulty gauge or possible continuing pressurization within the cylinder due to chemical reaction (contamination).

You will notice that when inspecting your extinguisher, there should be a pin (similar to a grenade)held in by a soft plastic thread or soft wire or some similar type of mechanism to prevent the unit being accidently discharged. Sometimes this pin works its way loose, I find that if the pin is hooked onto a rubber band and then the rubber band can be looped over the cylinder head to keep it in place, this allows the operator to still pull the pin before use (Do not use zip ties as they can be dificult to break).

All extinguishers these days are designed to be used upright..as they are a compressed cylinder with an internal syphon tube, it is comparable to a regular (but oversized) aerosol can, if you tip it while in use you will get propellent (non flammable in this case) and no active product coming out.

How long do they last? This has a double answer (triple actually),

1) in the sense of operating time, once the trigger is pulled and allowed to operate continuosly, a 1kg will only last about 10 seconds tops. As a result, you can extend its capabilities by using it in short bursts (quite often a short burst is all thats needed to knock the flames down anyway), see what the flames are doing, and if necesary hit it again.

2) As far as the cylinder goes, if the unit has not been used, and has ben maintained and its holding charge..pretty much until the unit itself fails (I will get to what to do with your extinguisher shortly to make sure its

maintained).

3) If the extinguisher is used in a commercial environment it is bound by regs governed by Australian standards, in this case they are required to be serviced 6 mthly, and pressure tested 5 yearly (private extinguishers are not required to go through these with the exception of car clubs etc where racing cars must have currently certified safety gear).

How to maintain your extinguisher? Well the first thing I have mentioned is keep an eye on your gauge, if it drops down to the recharge zone and the extinguisher HAS NOT been dicharged, this could be a faulty gauge or leaky seal on the head of the extiguisher that has allowed propellant to escape.

As far as the contents go..they are a really fine powder (essentialy baking powder) which will compress into a solid block over time. What fire equipment tech guys will do (during their 6 mthly check of commercial gear) is tip the cylinder upside down (make sure the pin is in) and tap it with a rubber mallet along the body, they then feel the powder shift (loosen) before putting it back on the hook.

The compaction of powder is eccentuated by fitting it upright in a vehicle (car caravan boat) as movement and vibration compacts the contents, I would recommend fitting extinguisher brackets on their sides, or better still upside down (I have seen this on some boats), where the action of actually picking up the unit for upright use loosens the powder immediately prior to use and the powder keeps loose while laid on its side. Commercially the loosening of the powder is required every 6 mths as part of its 'service', and you should try and get in the habit of doing it as well.

Make sure the discharge nozzle is not blocked by mud (insect nests), if your exinguisher has a hose, remove it, poke wire through it and blow it out to make sure it is clear.

If an extinguisher has been discharged, even slightly or dropped and a little puff of powder comes out, firstly check the head to make sure it has been discharged(you will see powder in the head, if yours has a hose take it off and double check), there is a fair chance (90%+) that the remaining propellant will continue to leak out by the next day effectively making that extinguisher useless...this should be then discarded or refilled professionally.

Cost to refill?

Varies, unless you know someone in the trade, you would be better dropping a small unit (1kg) to its appropriate area (gas cylinders) at the tip, the cost is generally equal to the purchase of a new one, larger ones...generally the larger it is, the more cheaper it is to have it refilled compared to replaced, but it will still have to be within pressure test date (or manufacture) to be legally refilled.

Lastly a few final words..

the contents of a DCP extinguisher are corrosive, any gear that has had powder coated on it should be thoroughly blown out and if practical washed or it can cause issues down the track. My previous job was in the commercial fire protection industry, maintaining and certifying commercial premises and in their obligations to comply with Australian standards conducting workplace fire training...prior to that (When I was in Victoria) I was an operational firefighter and training officer with an urban CFA brigade (equivelent to your Aux QFRS fire fighters)

.

So if you have extinguishers, check them, if you have any questions, post them here (others may benefit) or PM me and I'll see if I can steer you in the right direction.

Cheers Jay.

[rayke1938]

Thanks for a comprehensive post that should be compulsory reading for everyone. I have just checked all mine and they had all compacted.

Cheers

Ray

[Old Scaley]

Thanks for the post. It reminded me to check mine. I have a wood heater in the house so would not be without one in the house and one in the boat.

[goldnugget]

Hi guys, sorry I have been offline for a while.

Another extinguisher worth mentioning that is very handy is the water extinguisher (plain red large 9lt capacity), used primarily for paper, timber textiles ('A' Class materials).

It is a handy one to have on rural properties, as well as people that do out in the field welding, grinding etc (risk of starting grass fires), and people that love to go bush.

The water extinguisher (for home use not commercial, all commercial must be certified), is one of the only ones you can refill yourself with no special tools or gasses. Simply make sure it is fully discharged, unscrew the head off the cylinder (don't stand over it just in case it is still pressurised). Once removed you will see a little plastic tube inserted in the top, leave that there and fill with normal water (the tube ensures that water will only fill to the bottom of the tube, then overflow, allowing room for propellent)...if there is no tube, then leave a couple of inches gap from the top of the water to the top of the cylinder. replace the head tightly...you will notice a small valve on the head (schroder valve), give it a little spray of crc and hook up an air-compressor and fill till the gauge says its full...if your gauge is buggered and the needle doesn't move then take it to the pressure indicated in writing on the gauge (with your hand held tyre gauge). This is really handy for open and remote areas (particularly if you have a quality 4x4 compressor fitted to your vehicle) and a much better equivalent to a bucket of water.

[bootyinblue]

Top tip of fitting the dry chemicals upside down as turning them the right way up to use gives them one final chance to shake loose the powder and work far more effectively.

And when you do discharge an extiguisher, brace yourself and hold on! They do have some pressure to them and if the pressure doesnt stun you a little bit, the noise of the bigger funnelled ones and the amount of powder from the dry chemical ones will suprise you!

[goldnugget]

Just a quick note..thanks booty and everyone,...regardless of how an extinguisher is mounted it should still (powder type) be loosened (tipped, agitated) manualy about every six months.

My personal fave way of keeping a powder extenguisher is on its side, particularly in a vehicle because the motion constantly keeps the powder loose by movement.

Another thing too, you dont have to get too close to a fire with an extinguisher, depending on the size of the fire, a starting distance of about one and a half metres is good, preferably upwind, if the wind is working in your favour you can get closer as this disipates heat and smoke away from you and helps to get the powder 'in there'.

Particularly important to remember as Booty said, they are a pressurised unit, and if using an extinguisher on say a stove top fire, the initial pressure may well blow the contents out of a pot and initially spread the fire if you are too close..so start from a safe distance and if you need to, work your way in closer if it is safe to do so.

If using an extinguisher at the scene of an MVA (motor vehicle acident) where a fire has started be mindful of where you are standing and what liquids are scattered over the road and the accident scene, use the wind to your advantage. If you come accross an MVA and have an extinguisher but there is no fire, have it ready in case you need it.theres heaps more, I can go for ages on fire safety topics, all scenarios are diferent, if theres any specifics you want to know raise it on the thread or PM me.

Cheers, stay safe,

Jay