Thread: Fire Extinguisher Fun

Originally Posted by BobL

There were only heat detectors installed on an automated system but they were fooled because it was such a small fire and the air-conditioning system too efficient.
Interestingly in another lab we had a very low level slow smoke release when a mains power wire on a freezer door seal heater overheated and it lightly charred (yellow brown) the insulation.. In that lab we had a dust particle monitoring system that detected the smoke about 30 minutes before the smoke detector although we didn't find the source until much later.

Heat detectors in such an environment seems silly to me too. They are typically installed in areas where smoke detectors would produce fault alarms such as kitchens or areas that produce large amounts of steam or other simulated condition. They also detect the fire at a later stage than smoke detectors as the fire needs to have developed to produce some heat in order for the detector to "notice" an increase in the temp in the room or if it detects a rate of rise greater than a predetermined amount.

It's not unusual to attend an alarm where a detector has gone into alarm but attending crews cannot find the source of the alarm. re-setting the alarm and heading back to station without knowing what caused the situation is less than ideal because the last thing you need is for the place to burn down after it's been deemed safe. These days, finding the source of the alarm is much easier as we all have thermal imaging cameras now. It's easy to pick up the heat signature from such items as you explained or other common causes such as burnt out balasts in fluoro lights or downlight power supplies even without removal of the covers. It's certainly made our life so much easier and less hit and miss.

Also great for finding kids hiding in bushes at night after they light up the entire streets wheelie bins on bin night!

Simon

Originally Posted by simonl

It's not unusual to attend an alarm where a detector has gone into alarm but attending crews cannot find the source of the alarm. re-setting the alarm and heading back to station without knowing what caused the situation is less than ideal because the last thing you need is for the place to burn down after it's been deemed safe. These days, finding the source of the alarm is much easier as we all have thermal imaging cameras now. It's easy to pick up the heat signature from such items as you explained or other common causes such as burnt out balasts in fluoro lights or downlight power supplies even without removal of the covers. It's certainly made our life so much easier and less hit and miss.

I worked in a 7 storey lab building in the US for a few years and was there when the fire alarm went off (multiple times). There is a whole drama around this I won't go into so to cut a long story short, the alarm was from a smoke detector in a lab on on level two but there was no fire or hint of smoke in that or adjacent rooms.This happened several times before they got out the thermal imaging gear and swept the whole building. It was a very big building with a large central services core where all the ducting and services ran so there were lots of normal hot spots so it took hours to check everything but they found nothing. After that there were no more alarms but everyone was on edge because it was a building full of biohazards and radioactive stuff.

Weeks later someone noticed a fluoro in rarely used services tunnel in the basement connecting the cores of adjacent buildings was not working, and when it was finally attended to a burnt out ballast was found. It was reckoned that smoke from the ballast had slowly worked its way along the tunnel roof and into the core. The lab where the alarm had gone off had a fresh air vent that drew air from the outside but it was leaking and drawing air and smoke in from the core. Every time someone went down the tunnel and they turned on the lights, thats what triggered it off. It was subsequently tested and confirmed to be the case. There were multiple smoke alarms high up in the roof of the core but the layout of the stuff in the core directed the smoke up to where the leak in the vent was sufficient to grab all the smoke.

Originally Posted by simonl

You'd be surprised at what is still flammable in a room. Besides, I would expect on such systems that they would have a dry pipe system. The sprinkler plumbing is charged with nitrogen so that in the event of a damaged sprinkler head, initially only nitrogen gas comes out. Workers will then have a pre-set amount of time to investigate and then override the system to prevent an unnecessary discharge from the head. Can't state for sure that is what is installed but they are available. All depends on what the people with the $$$ are prepared to pay when the place is built.

Also, bear in mind that sprinklers are not necessarily designed to extinguish the fire, they are primarily designed to initially inhibit fire spread and extension to give occupants enough time for safe egress until a response from the local fire brigade. The BCA (building Code of Austrailia) is very strict with building of this class as it invariably has occupants who may be non ambulatory. As such they will be venerable in the event of an evacuation. The BCA does not concern itself with the cost or damage to equipment in the event of fire, it's main concern is the safe egress of ALL occupants in the event of an incident. Having said that, there are provisions in the BCA that enable designers to "deem to satisfy" the BCA by other means if they can demonstrate compliance. New technology or installing a different system that still achieves the same level of protection but does not pose the same damage risk to machines can therefore be installed.

Simon

Would that still apply if the sprinklers are installed as a requirement of the National Trust because the building is listed in their register. The Gables building at work is probably one of the most recognisable winery linked buildings in Australia for those who drink wine.

Dean

Originally Posted by cba_melbourne

I is crazy. In new buildings, the laws require there to be sprinklers even in MRI and NMR rooms. The MRI magnet is filled with liquid Helium at -269 degreesC, and sometimes additionally with large amounts of liquid Nitrogen at -196C. There is absolutely nothing that could burn. Yet an expensive mess is to be expected if a sprinkler gets damaged during a Helium fill or suddenly leaks.

The problem with liquid N2 and Liq He is that they both have a BP below that of LOX -183ºC.
This means O can condense out of the air and LOX will assist the rapid burning of lots of things that normally won't burn or won't burn that fast in air

Originally Posted by Oldneweng

Would that still apply if the sprinklers are installed as a requirement of the National Trust because the building is listed in their register. The Gables building at work is probably one of the most recognisable winery linked buildings in Australia for those who drink wine.

Dean

I cant be sure. The legislation pertaining to national trust if somegthing I not familiar with.

Simon

Originally Posted by simonl

At work, start of every shift At home I have 2 vaporizing liquid extinguishers. These are the ones that replaced the ozone depleting BCF (Bromo,chloro,Difluromethane) which are OK to use but a little expensive to buy. Vaporising liquid are the go in the shed as it does not create a mess that costs more to clean up than the fire! That white powder makes a lovely grinding paste! Also, vaporising liquid extinguishers are "reasonably" easy to test as you can tell with a shake how much liquid is there which is a backup to just relying on the gauge. As it requires pressure to store it in the liquid phase, you know it must be charged. WRT Dry powder, once they are discharged even the smallest amount of powder, they will go "flat" very quickly since the valve cannot seat properly as it has powder in it, within hours the charge of dry nitrogen will escape and you will end up with an extinguisher with near on 9Kg of powder but no pressure. While the gauge should reflect this, if the extinguisher is old it's not unusual for the needle to stick and still show "full" in the green zone. Best way to check is to look in the nozzle or give it a tap. It should be clean and have no sign of powder, if it has then it's been used. Of course nothing beat water for A class fires.... as long as any electrical hazard has been isolated. Cheers, Simon

Hello Simon,

Any chance of a bit more information regarding the vapourizing liquid extinguishers? Size, cost, best place to buy. I have a dry powder extinguisher in the shed which I will replace.

Bob.

Originally Posted by Anorak Bob

Hello Simon,

Any chance of a bit more information regarding the vapourizing liquid extinguishers? Size, cost, best place to buy. I have a dry powder extinguisher in the shed which I will replace.

Bob.

Me too, please.

Originally Posted by Anorak Bob

Hello Simon,

Any chance of a bit more information regarding the vapourizing liquid extinguishers? Size, cost, best place to buy. I have a dry powder extinguisher in the shed which I will replace.

Bob.

Hi Bob & Block,

Give me some time, I'll ask when I'm back at work. I have a couple but they didn't cost me anything as I "acquired" them from a workmate who knew a mate who worked for an extinguisher servicing company. I installed a garage door opener when he built his house and the extinguishers were a payment, even though I did it as a favour.

To identify the type of extinguisher, they are red with a yellow band. I'll post a pic of one. Only thing you really need to consider, do you want an extinguisher suitable for flammable liquid? These extinguishers are rated as A(E) which means they are suitable for class A fires: wood paper, textiles etc. and the (E) indicates it can be used where an electrical hazard exists. If you want an extinguisher that will handle a flammable liquid fire then you need one suitable with (B) class fires. This is why dry powder extinguishers are so popular, you can buy them with an AB(E) rating, even though I don't like them because of the mess they leave!

Just quietly, I'm confident that any flammable liquid fire I have in my shed I will handle with my A(E) vaporising liquid extinguisher, even though it's not designed for it. Main reason for this is because there is a chance the vaporising liquid can splash the flammable liquid when it vaporises and spread the fire. But with some careful technique, this can be mitigated to some extent.

I'm almost embarrassed to confess that I have 4 extinguishers, 2 vaporising liquid, a dry powder and a 9L water stored pressure. Not that I'm pessimistic about having a fire, it's just that I have accumulated them over the years. Also, the 9L water makes a good water pistol when my nieces and nephews are around!

Anyway, I'll have a look for you guys. I am lead to believe they are not cheap though, compared to the dry powders.

Cheers,

Simon

This is what they look like

Cheers

Simon

Originally Posted by simonl

Hi Bob & Block,

Give me some time, I'll ask when I'm back at work. I have a couple but they didn't cost me anything as I "acquired" them from a workmate who knew a mate who worked for an extinguisher servicing company. I installed a garage door opener when he built his house and the extinguishers were a payment, even though I did it as a favour.

To identify the type of extinguisher, they are red with a yellow band.

I had a bit of a look on the web and it jogged my memory from fire safety training days at uni that there is a bit of confusion about "the extinguishers with the yellow band"

For example this one (http://www.fireextinguishershop.com....ainless-steel/) has a yellow band but is not an "vaporising liquid" extinguisher but a "wet chemical" extinguisher used to fight far and oil fires in restaurants.

This one http://lrd.kangan.edu.au/auto_toolbo.../fire_ex_6.htm also says it is a "vaporising liquid" extinguisher but its most definitely not.

Using a "Wet chemical" extinguisher on electrical apparatus is considered dangerous.

The Wormald fire page shows all the types of extinguishers http://www.wormald.com.au/fire-produ...classification

It shows the "vaporising liquid" extinguisher as having a bright yellow band while the wet chemical" extinguisher as having a beige or as they call it "oatmeal" band but unlike the other extinguishers I notice there is no link to the specific details of the vaporising liquid type of extinguisher.
The only extinguisher with a distinctly yellow band for which details are provided is the Sapphire MRI extinguisher http://www.wormald.com.au/fire-produ...-extinguishers which is a type of "vaporising liquid" extinguisher. Perhaps this has taken over as the standard "vaporising liquid" extinguisher?

It looks like the "vaporising liquid" extinguishers are not that easy to get hold of.
They might only be available as part of a contracted service or plan with a fire service authority.
When we purchased the Sapphires back in 2009 I think the cost about $1200 each.

Crickey Bob! I didn't know they cost THAT much. I'm glad I didn't just discharge it in order to cool my drinks! The Wet Chemical extinguishers are called Oatmeal in colour and are specifically for fat fires. They contain a alkali (from memory) which when mixed with the burning oil, turn it into a soap, and extinguishing the fire. Absolutely useless for any other fire, but very good for that specific fire hence why they are widely used in places light KFC, Maccas, and other food places. It also creates minimal cleanup after a fire although any fire at a food place will need to be inspected and signed off by the health inspector prior to commencing trade again.

I have never seen a Wet Chemical extinguisher with a yellow band. I have only ever seen them in Oatmeal in colour. Having a yellow band would cause confusion.

Cheers,

Simon

Originally Posted by simonl

the 9L water makes a good water pistol

even if it is a tad hard to run with.....lol....and also good for weed sprayer

I get outdated but unused, water ones from the school (I do work for) for nothing...new ones are only an extra $15.00 over the cost of pressure test and refill, so when I want I ask for one
fill it up with water (and weed killer if required), some air and ya ready to go....

Originally Posted by eskimo

even if it is a tad hard to run with.....lol....and also good for weed sprayer

I get outdated but unused, water ones from the school (I do work for) for nothing...new ones are only an extra $15.00 over the cost of pressure test and refill, so when I want I ask for one
fill it up with water (and weed killer if required), some air and ya ready to go....

The local waste transfer station also have lots that get thrown our after they come up to their hydro test date. They are also a good source of stainless steel sheet.

Not much to go wrong with them, perhaps a new O ring seal or even a new trigger or gauge and they are good to go. They have a schrader valve so can easily be recharged to their nominal 700 Kpa. The biggest trick is to make sure they have pretty close to 9L. Any less and you wont have the same firefighting capacity and any more and you will run out of pressure before the contents are emptied. There is usually a sleeve inside the neck that extends into the cylinder. If you fill it up with the liquid to the bottom of that sleeve then you have 9L. Just make sure you never have your face or head over the valve or in front of the gauge. If ever they fail while recharging, you don't want your face in front of them….. Not that they fail very often.

Simon

In the linked "Fire Extinguisher Shop" there are CO2 extinguishers. How would these go for a typical shed application, i.e. flammable liquid fire? They say they can be used on Class B Fires - flammable and combustible liquids but then state that they have limited effectiveness.

I had a look around the office here and there are both CO2 and dry powder type extinguishers. I'm sure most of the 40 odd staff would not be aware of the after effects of using the dry powder extinguisher.

BT