Are portable water mist extinguishers safe on gas fires?

[Guest PaulNewm]

Hi

I have seen the dry water mist extinguishers with an AF rating. Are they safe in a household, which typically has petrol (B rating) in the garage, gas fire (C rating) in the kitchen and electrical risks in computers etc? The manufacturer says the extinguishers are suitable for B,C and electrical. But there is no certification!

Paul

[Tom Sutton]

It appears they are LPCB approved to EN3, if so; they will have an A-F rating which means they will extinguish all those classes of fire.

What is very important is how those fires are tackled, each one is different. For instance gas, you never extinguish the flame because you will have an explosion risk you should isolate the appliance from the mains and this also applies to electric appliances, then you can deal with it as a class A risk. As for the 35kV dielectrical test ensures that the extinguishers can be safely used near electrical equipment.

[Safelincs]

The water mist extinguishers, while so far only being certified for A and F ratings are capable of fighting B and C ratings as well. So far there is no relevant approval process that would allow a water based extinguisher to be tested for B and C ratings. The manufacturer is currently trying to get this changed, though.

I attended a demonstration of the water mist extinguisher recently and you can see the B and C demos following this link.

Harry

[Safelincs]

I heard an interesting discussion today where the small 1 litre dry water mist extinguisher was considered as a replacement for halon riot police extinguishers. Anybody any views?

Harry

[Tom Sutton]

They have a very poor class B rating (21B) for the 6litre and the 1litre is not indicated. I wonder how they would preform on a running/spill petroleum fire?

[Tom Sutton]

I heard an interesting discussion today where the small 1 litre dry water mist extinguisher was considered as a replacement for halon riot police extinguishers. Anybody any views?

I have done a little research and assuming the extinguisher is for public order policing where police officers can get flammable liquids on their clothing.

For a class “B” fire in a container then I would not recommend a dry water mist because of the rating but the above scenario is more akin to a spill type fire and the method of rating is calculated differently. It says the recommended minimum rating = 10 X the amount of flammable liquid spilt in litres. Therefore the contents of a petrol bomb are likely to be about 0.25litres X 10 = 2.5 and the 1litre water mist extinguisher has a rating of 5B then in theory it should be adequate.

Having said that, I would still be cautious and conduct some practical tests, using a dummy dressed in riot gear to prove it would be effective.

[Safelincs]

Thanks, Tom, I think you are right, it really needs testing. We might give it a try ourselves before taking it any further. If we do, I will post a video.

Harry

[Tom Sutton]

Harry I stand corrected the 1ltr version doesn't have an A or B rating therefore I would not consider it, on reflection you would have to use the 6ltr as a minimum if you require a multi-rated extinguisher.

[Guest Jerzy Klimkowski]

Some two years ago, I have designed the core of the CeaseFire, Ogniochron, Telesto and JewelSaffire water mist extinguishers. This is the unit called 'pulsator'. These watermist extinguishers, provided the nozzle, called 'Ela', is correctly selected should work well on gas fuel fires and on fires on human clothing (there are papers to corroborate this mist stream to be completely safe for human skin). However, this is not the case for some high-pressure extinguishers usually of a German or American makes, because they have the throw which is a bit excessive and te droplets a bit too large. As to the required volume of the extinguishing agent (pure water) - take your pick, 1, 3 and 6 ltr of water in twice the size cylinders are available. There was some work on building wheeled units of much larger capacity, but as I am no longer with the Telesto or the Jewel I cannot be sure. I am currently working on a more robust design, for more info contact me directly at jerzyklimkowski@wp.pl, this is not the place to locate my commercial messages :-).

[Guest vishwash]

Some two years ago, I have designed the core of the CeaseFire, Ogniochron, Telesto and JewelSaffire water mist extinguishers. This is the unit called 'pulsator'. These watermist extinguishers, provided the nozzle, called 'Ela', is correctly selected should work well on gas fuel fires and on fires on human clothing (there are papers to corroborate this mist stream to be completely safe for human skin). However, this is not the case for some high-pressure extinguishers usually of a German or American makes, because they have the throw which is a bit excessive and te droplets a bit too large. As to the required volume of the extinguishing agent (pure water) - take your pick, 1, 3 and 6 ltr of water in twice the size cylinders are available. There was some work on building wheeled units of much larger capacity, but as I am no longer with the Telesto or the Jewel I cannot be sure. I am currently working on a more robust design, for more info contact me directly at jerzyklimkowski@wp.pl, this is not the place to locate my commercial messages :-).

hi there i want to know the function of this pulsator tube how this tube break water in to fine mist or dry mist .

is there some one who can explain me this.

[Tom Sutton]

The distinguishing feature of Telesto’s dual fluid, low pressure technology is its ability to atomize liquids into extremely small droplets and carry the droplets on an air stream. By adjusting nozzle design, water volume and air pressure parameters. How they do it will be a trade secret and I am sure we will not know for a very long time.

[Guest TJ from Brum (England)]

The distinguishing feature of Telesto’s dual fluid, low pressure technology is its ability to atomize liquids into extremely small droplets and carry the droplets on an air stream. By adjusting nozzle design, water volume and air pressure parameters. How they do it will be a trade secret and I am sure we will not know for a very long time.

All your info here's very useful, many thanks.

[AnthonyB]

Whilst Firebug did mark their water mist for Class c they are no longer in the market and so you have the Jewel product which is only marked AF(E)

It can be used on class B & C, but as it doesn't meet EN3 criteria for these fire types it can't be marked as suitable for them, the Class B ratings being very poor.

It's only British sensibilities that steer people from using water mist (& indeed water spray/foam spray) on electrical fires. EN3 (the base document) allows these extinguishers to be marked as suitable for direct use on electrical fires up to 1000V but currently only Jewel (only on their water mist) and Britannia (all wet models other than water jet) go as far as to implement this.

They are safe directly on electrics - a client used one on a live 415V industrial tumble drier on fire (after the CO2 was ineffective) and of course was totally unharmed.