Author Topic: Foam extinguishers or Water?  (Read 12978 times)

Offline Underground

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Foam extinguishers or Water?
« on: July 13, 2007, 07:39:02 PM »
I wondered if there is a simple explanation as to why offices tend to have a lot of foam extinguishers in them instead of plain old water ones.  Is it a cost issue?

Offline AnthonyB

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Foam extinguishers or Water?
« Reply #1 on: July 13, 2007, 07:57:31 PM »
Two main reasons, a few lesser ones:
1) Lighter & easier to handle - you can get 13A from a 6 litre foam spray, saving you several kilos in weight over a 9 litre plain jet water, which is also traditionally 13A rated (many now are 21A, but most people calculating requirements treat them all as 13A rather than research which make is being used)
2) Most (but not all) spray foam extinguishers have passed the EN3 35kV dielectric test meaning if sprayed on electrical equipment the operator is not at risk from a shock along the discharge unlike with plain water jets. This means in the modern mixed risk office with plenty of electrical equipment around they are safer in use
3) Smaller extinguishers take up less space, which is sometimes a factor with end users
4) Many modern materials like plastics can act as liquifiable solids once alight, putting them into Class B

Personally I never install 9 litre plain waters anymore and in fact prefer the water additive spray (or the 'super' foam spray that some manufacturers offer instead/as well) as you can get 13A from a 3 litre extinguisher, making it easy for operators to handle & move, plus the dielectric protection and there is minimal cost difference between the three types anymore
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Offline Redone

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Foam extinguishers or Water?
« Reply #2 on: July 13, 2007, 09:18:48 PM »
Agree with everything you say Anthony, but you cannot beat a 6m jet and 9ltrs of wet stuff, admittedly in trained hands.

Offline kurnal

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Foam extinguishers or Water?
« Reply #3 on: July 13, 2007, 10:22:07 PM »
The foam spray is wetter than the wet stuff.
I  too very rarely specify the 9l water any more- just from the manual handling point of view. Applying the manual handling risk assessment along side the fire risk assessment you cant justify it any more-  there is  an equivalent lighter product available so there is a duty on the employer (as opposed to the RP) to specify the lighter one.

But there is one factor that may change my mind- duration. For some difficult to wet fires there may be a benefit in a 90 second discharge over a 20 second time to counter re-ignition.  The ratings are just given based on test fires after all.

Offline Redone

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« Reply #4 on: July 16, 2007, 03:23:21 PM »
I like the longer duration as well Kurnal plus the safer working distance with the jet.  Office girls do struggle with the 9ltr, care home staff seem to manage, manual handling all day I suppose.  I don't supply, only train with the types already on site, bar powder.

Offline Richard Earl

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Foam extinguishers or Water?
« Reply #5 on: July 16, 2007, 04:09:49 PM »
i agree i always advise afff in offices but i have been told by some one that afff MAY be banned due to its non enviromental freindliness and replaced with pure water??????? dont know how this one will go down mmm we will wait and see

Offline AnthonyB

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« Reply #6 on: July 16, 2007, 09:02:18 PM »
Some AFFF compounds have always been withdrawn, however a variety of Biodegradable compounds that aren't strictly AFFF, but have similar properties are readily available: Saffires Foam & Aquamist compounds, Chubb's PuraFoam & Nu Swift's ECO Premier (also used by it's sister companies like GFA, LW Fire, & its trade wing BWH now used by MK Fire).
Many of these new compounds have combined impregnating & wetting as well as foaming properties and boast very high test ratings. The only problem is that with most maintenance companies other than the original maker/supplier this is all lost on recharge as for simplicity & economy they only stock & bung in normal 6% AFFF
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Offline Richard Earl

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Foam extinguishers or Water?
« Reply #7 on: July 19, 2007, 09:11:28 AM »
hi i thought saffire had with drawn their enviro foam as it was found not to be what it said on the tin??????

Offline Jason Miller

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Foam extinguishers or Water?
« Reply #8 on: July 19, 2007, 02:02:37 PM »
Anthony is a great source of knowledge and is correct.

9 litre water was the standard until the "spray" nozzle was combined with AFFF foam to make a 6 litre size adequate. And, yes, you'll never get them refilled with the original foam so don't worry about the "environmentally friendly" versions.

This has been improved upon by the "water additive" in 3 litre size for a 13A (sold by Chubb as Hydrospray at £189 but by "proper" online companies for around £33) rating or 6 litre for 21A but many extinguisher companies can't afford to have the extra types in stock because they are not run professionally. They also don't want to have to stock the additive for refills.

As for discharge time, I'd be disappointed if someone was hanging around for 60-90 seconds trying to put a fire out in a building so the shorter time is also a great safety factor.

And, these days, when the 5 year discharge test is due, it's often cheaper to get a new one online than have the old one refilled.

Jason Miller

Offline Redone

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« Reply #9 on: July 19, 2007, 03:44:47 PM »
Care staff have no choice but to hang around in the building, as they have the responsibility for the evacuation of anyone at risk, that's why in my opinion the 9ltr water with it's longer throw is safer to use, puts a bit of distance between you and the nasty bit, plus, and it's a big plus I believe, staff can (in most cases) hit a fire anywhere in an occupants room from the room door, without the added worry of the door closer operating and closing them in.  One step back, the door closes and they are safe, relatively speaking.

I know you need to move closer to complete the job, but an initial attack in an enclosed room is about as dodgy as it can get.

Offline gm137

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« Reply #10 on: July 30, 2007, 06:34:16 PM »
In training scenarios, I've found that the wide spray pattern of the discharge from AFFF extinguishers makes it easier for novice users to tackle class A fires when compared with standard water extinguishers (producing a jet). As Redone states, though, there may be advantages to having water extinguishers available for trained users.

Offline jayjay

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« Reply #11 on: July 31, 2007, 12:43:17 PM »
Must agree with Redone, that is exactly what I tell the res care staff when training . Foam extinguishers require the user to approach a fire much closer with increased risk.

Foam extinguishers should use for what they are designed for, flammable liquids but not deep fat fryers.

It always amazes me when I see foam extinguisher training films with a nice fire in a tray of flammable liquid then the operator sucessfully puts out the fire.
In over 30 years of fire safety I  have never visited a premises and found trays of flammable liquids or even similar situations where the training would be applicable.

Offline gm137

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Foam extinguishers or Water?
« Reply #12 on: July 31, 2007, 03:08:47 PM »
Jayjay makes a good point:  realistic training is a key factor in sucessful first-aid firefighting, particularly when an extinguisher requires a comparatively close-range attack (as with AFFF).

Many fire procetction companies have special offers under the title of "office protection pack" or similar, comprising a 2kg CO2 and a 6 or 9 litre AFFF extinguisher along with stands, signs etc. The reason most often cited for including the AFFF unit is the increased fire rating it gives compared to an equivalent capacity water unit.

Offline Jason Miller

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Foam extinguishers or Water?
« Reply #13 on: July 31, 2007, 03:12:48 PM »
Water additive should be specified in place of AFFF unless it is for flammable liquids.

As far as realistic training, it's just not practical and I expect it to become more and more simulated with the next generation to be simulated flames on a waterproof screen and using simply water with air (this is happening in the USA and we will follow eventually).

Jason