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Topic Title: Water mist extinguishers
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Created On: 12 August 2017 09:25 AM
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 12 August 2017 09:25 AM
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lyledunn

Posts: 1098
Joined: 13 August 2003

Anyone with practical experience of use or specification of these portable extinguishers specifically for electrical fires?

-------------------------
Regards,

Lyle Dunn
 12 August 2017 06:28 PM
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sparkingchip

Posts: 9838
Joined: 18 January 2003

I installed the electrical supply and first fixed the cabling for a Plumis Automist system

It is "portable" in do much as it can operate off a tank of stored water that can be stood in a hallway or the like with a decorative cover around it if needs be.

I don't know how it would cope with a electrical fire.

There is a discussion on the forum in relation to the installation I did as it needed to go on a RCD protected supply as it is in a TT installation and I could not justify leaving the RCD out, but wanted a 13 amp outlet that would not be prone to any nuisance tripping.

Andy Betteridge
 13 August 2017 09:19 AM
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lyledunn

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Andy,
These are high pressure de-ionised water mist in manual extinguisher form. They claim to be safe for use on live electrical fires. Tested at 37Kv for use up to 1KV at 1m and accredited by LPCB etc. I look after general safety in over 100 premises and it would be an enormous benefit to have a single type extinguisher device.

-------------------------
Regards,

Lyle Dunn
 13 August 2017 10:32 AM
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sparkingchip

Posts: 9838
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A new one on me.

It is probably a lot safer for the person using the extinguisher to be surrounded by a mist of water that gas or powder, beyond that I've nothing to contribute.

Andy Betteridge
 13 August 2017 11:25 AM
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broadgage

Posts: 2322
Joined: 07 August 2007

I have seen a demonstration of a water mist extinguisher, intended for railway use, it was impressive.

Several test fires were extinguished.

One was petrol spilt onto grass
Another was a chip pan.
The last was a vehicle adjacent to live 11KV conductors, a simulation of a vehicle striking a pole and bringing down the wires.

It was also suggested that one of these extinguishers could be used on a person with burns. Clean water applied generously but without undue force is often the best first aid treatment for burns. The pure water applied as a mist would be excellent for this purpose.
 14 August 2017 08:32 AM
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Zoomup

Posts: 3169
Joined: 20 February 2014

Originally posted by: lyledunn

Andy,

These are high pressure de-ionised water mist in manual extinguisher form. They claim to be safe for use on live electrical fires. Tested at 37Kv for use up to 1KV at 1m and accredited by LPCB etc. I look after general safety in over 100 premises and it would be an enormous benefit to have a single type extinguisher device.


Back in the 60s/70s NuSwift, an extinguisher firm in London, said that its water extinguishers could be used safely on electrical fires as the droplets of water sprayed from the portable extinguisher hose could not carry an electrical current because they were separated. This though would not prevent an accumulation of water pooled around on the floor causing an electrical shock hazard. But with mist, things may be different as it has less volume of water presumably being used.

Z.
 14 August 2017 09:15 AM
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AJJewsbury

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How effective are these mist extinguishers if there's a draught in the room? Either from an open window on a windy day or from mechanical ventilation or fan-assisted heaters. Could it stop the mist reaching the seat of the fire?
- Andy.
 14 August 2017 11:18 AM
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OMS

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Joined: 23 March 2004

Not very Andy - similar to a gas suppression system, they tend to be in "lights out" areas that can be closed up (or remain closed up) before deployment (with appropriate pressure relief venting)

I've used them in switchrooms, transformer rooms, UPS battery rooms etc instead of inert gas suppression systems (typical in data halls)

I've also deployed them in generator rooms/containers and similar plant spaces but you do need to shut louvres first

They also have a big application in maritime applications

Perhaps try a google for Marioff for some typical self contained systems that can deal with engine rooms to about 500m3 or above

I've not yet been brave enough to put one in a data hall however - although we are looking more at hypoxic systems rather than a more traditional argon/nitrogen mix to give a resultant O2 concentration of around 12% - so not instantly incapacitating to persons present

Regards

OMS

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Let the wind blow you, across a big floor.
 14 August 2017 12:44 PM
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weirdbeard

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Originally posted by: lyledunn

These are high pressure de-ionised water mist in manual extinguisher form. They claim to be safe for use on live electrical fires. Tested at 37Kv for use up to 1KV at 1m and accredited by LPCB etc. I look after general safety in over 100 premises and it would be an enormous benefit to have a single type extinguisher device.


Hi lyle, wouldn't a draw back of the water mist compared with an abc type fire extinguisher be that in unheated rooms or exterior, they could freeze?

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:beer)
 14 August 2017 04:06 PM
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lyledunn

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Good questions AJ and WB. I will seek answers. So you have deployed them OMS without any concerns? The premises I look after would be simple with proposed replacement of CO2, wet chemical and foam at end of life. The key advantage is training.

-------------------------
Regards,

Lyle Dunn
 14 August 2017 05:41 PM
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Dave69

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We install these in plenty of places, they will extinguish small fires but we use them to protect escape routes. Main thing is they make one hell of a mess when they go off so we use two detectors to trigger them, both have to be in alarm before it goes off. Also they are not connected to the premises fire alarm system as the last thing you want is them going off in an upstairs landing when the alarm is in a cellar.
 14 August 2017 06:24 PM
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OMS

Posts: 22314
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Originally posted by: lyledunn

Good questions AJ and WB. I will seek answers. So you have deployed them OMS without any concerns? The premises I look after would be simple with proposed replacement of CO2, wet chemical and foam at end of life. The key advantage is training.


For clarity Lyle - yes, we've used water mist suppression as fixed systems for rooms of "high hazard" - I've not deployed portable water mist - it's not a fixed building service to be honest.

For portable extinguishers, as you say, the principle issue would be the training

To be honest, if the extinguisher freezes, then that would be unusual as everything else would also be frozen - and we tend to maintain most internal spaces at a fabric protection temperature to prevent this - although, clearly some facilities do have unheated spaces by design that might also currently contain other types of portable extinguishants

From a draught perspective, then any draught that would influence a water mist would also influence CO2 - but perhaps less of an effect on wet chemical or powder as they tend to "cling"

As ever, if you are trying to change the fire precautions, then the responsible person under the RRO needs to evaluate that change as part of the risk assessment

One for FireNet perhaps ?

Regards

OMS

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Let the wind blow you, across a big floor.
 14 August 2017 11:16 PM
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Timeserved

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Lyle,water mist seem to be all the rage at the moment and yes they are safe to use on electrical fires, but I can't stop thinking why you would want to go to all the trouble, why not replace the existing portable fire extinguishers with an "all risk" one instead? These cover most classes of fire.
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