Fire ratings and measurements.

[TFEM]

Can anybody tell me when fire ratings were introduced and when the standard measurement changed from gallons to litres?

Ha ving a little problem with an insurance company who state that a 3 litre hydrospray is not satisfactory....they are insisting on a one gallon water extinguisher!!

John

[Golden]

Soda acid or stored pressure?

[colin todd]

Not sure that ratings are the answer to everything.

[AnthonyB]

1 gallon water? Are they using the old FOC Rules circa 1920's to 1960's?

Fire ratings have existed since the late 70's in the UK with the introduction of BS5423:1977 & subsequent editions and the type/size charts went out of the window in the following years.

I suggest that you refer them to BS5306-8 (and it's original combined service/installation edition BS 5306:Part 3:1980) and bring them into this century

I might have a 1 gallon water extinguisher in my museum you can buy, it's 40 years old but has FOC approval!

Fire ratings are not the be all and end all (no one uses them much any more it seems anyway) nor is slavishly following BS5306-8 which appears to have turned into a salesman's charter as much as a technical guide, but they are a benchmark if nothing else

[TFEM]

Thanks Anthony.
The point that I'm trying to get across is that the 3 litre hydrospray/foam spray with a 13A rating has the same fire fighting capacity as the old fashioned 2 gallon water....no idea where one gallon comes from.
This can then be read in conjunction with 5306 Part 8 which refers to 13A rated extinguishers.
John

[lancsfirepro]

I'm equally flummoxed by the reference to a gallon extinguisher.  Fire ratings aside, I do tend to agree though that a 3 litre hydrospray is unsuitable for most applications.  Yes they have a 13A rating but the skill needed to achieve that fire rating is WAY beyond that of your average person.  As such, I won't have anything to do with supplying 3 litre extinguishers for class A cover.

Quote from BS5306-8:2012
Fire ratings of extinguishers are determined during controlled tests by experienced users. When using the fire rating of an extinguisher to calculate the required levels of coverage, it is therefore important to take into account the total discharge time of the extinguisher, and its range of discharge, in combination with the levels of experience of the potential users.

I visited a warehouse in the Wirral that was storing bog rolls a few weeks back and it had 3 litre hydrosprays fitted - scandalous.  They don't have the discharge length.

[TFEM]

But the same applies to a 9 litre water with a13A rating. That rating is still achieved by professionals. They both have the same fire fighting capacity.
We've put a few 3 litres in small schools where they're easier to handle and less likely to actually get used but are now installing 6 litre water sprays.
Agree though that premises with greater risk would necessitate something more substantial.
John

[AnthonyB]

Fire ratings alone, then if you need 13A you comply whether you have an old cumbersome 9 litre water jet or a 2 litre super foam (yes you can get 13A from a 2 litre, TOTAL make one).

Looking at the bigger picture though, I agree there are several factors - potential users, weight, discharge pattern/range, 35kV test pass needs, B or F rating needs - that all need to be accounted for.

For 99% of applications the 9 litre water jet is obsolete (if you genuinely need the range and power, don't need to worry about electrics and have suitably fit staff it still has a role.)

Personally for general use it's the 6 litre water spray, if you need B rating 6 litre foam spray although I will use the 3 litre water additives and foams where a compact light weight extinguisher is needed.

I'd not expect the average user to try and put out a 13A sized fire, that's quite big, hot and smoky for the typical indoor workplace with no PPE, 5A is more of a 'small' fire. A more industrial environment with decent fire team training is different, but not as common.

[colin todd]

I am with Gazza the Coal on this one. If someone invented a super agent that could get a 13A rating with a teaspoonful of the agent, when tested with a skilled operator, would you want a wee girl in an office to use it on anything.

[TFEM]

We are all taught that 13A is the benchmark and 5306 Part 8 confirms that.
Surely 13A is 13A in a wet extinguisher? We can't go around saying that anyone likely to use it needs to be vetted as to their ability to tackle fires and provide extra cover if not considered capable?
It's all down to the floor area and additional risk. I can't go into a convent and say "the standard says 1 x 13A rated per 200m2 but I'm going to recommend you have 2 x 13A per 200m2 because you're all weak old ladies".
Or should I?
John

[AnthonyB]

We are all taught that 13A is the benchmark and 5306 Part 8 confirms that.
Surely 13A is 13A in a wet extinguisher? We can't go around saying that anyone likely to use it needs to be vetted as to their ability to tackle fires and provide extra cover if not considered capable?
It's all down to the floor area and additional risk. I can't go into a convent and say "the standard says 1 x 13A rated per 200m2 but I'm going to recommend you have 2 x 13A per 200m2 because you're all weak old ladies".
Or should I?
John

In said convent you might not use one 9 litre 13A waters @ 14.3kg per 200m2, but a 3 litre 13A water additive @ 4.4kg. Not extra cover, just the same cover in a different way. 13A is 13A, how you provide it does require an assessment of different factors, operator ability does have some relevance.

[kurnal]

Operator ability and duration of discharge are linked - if I dont use the media effectively and it does not last very long then I am less likely to extinguish the fire.  

13A is the benchmark  though in the convent the fire risk assessment may bring other factors into play such as the size of any possible fire and ability/ training/ experience  of the occupants. I would happily provide smaller extinguishers with lower ratings if the FRA justified it and would never recommend multiple extinguishers of the same type at the same fire point, just to meet the BS5306 ratings. I think providing multiple extinguishers may encourage people to use more than one extinguisher on a fire and place themselves at risk.

Personally I am pretty impressed with the wetting / cooling ability of these 3 litre water with additive extinguishers though I experience them on the training rig these days. The throw is not great I agree.

[TFEM]

Operator ability and duration of discharge are linked - if I dont use the media effectively and it does not last very long then I am less likely to extinguish the fire. 

........but the same applies to a 9 litre water!!!!! Yes it has 3 times the capacity but the fire rating (ie that extinguishers ability to put out a certain size of test fire) is exactly the same.

That's the point I'm trying to get across.

Agree that consideration should be given to how you provide the required cover in a building but at the end of the day, a 13A rated 9 litre water jet extinguisher and a 13A rated 3 litre hydrospray will/should put out exactly the same size test fire therefore to say that "a 3 litre is not sufficient, we want a bigger extinguisher" is not a valid comment.

John

[lancsfirepro]

Seems to me that the insurance company are using a bit of common sense by acknowledging that a 3 litre extinguisher isn't as effective in the average user's hands as a larger model.  If that's their policy, that's their policy.  I'd argue the case for that all day long.

13A ratings were about all 9 litre water jet extinguishers could manage.  Fit a spray nozzle on a 9 litre water and you can readily achieve a 21A rating.  Fitting a spray nozzle to a 6 litre water extinguisher allows you to readily achieve a 13A.  To achieve a 13A with a 3 litre extinguisher is not that easy; one because of the shorter discharge time and two, because you have less media.  Granted it's a more effective media but unless you know exactly what you're doing you'll get no where near a 13A with 3 litres.  As far as the EN3 test fires go, the extinguisher can be as effective as a 6 litre but remember that there's quite a difference between a 13A fire and a 21A fire.  A 6 litre will achieve a 13A readily and will go some way towards a 21A rating.  A 3 litre will just scrape a 13A.  You can't say that they have the same performance just because they achieve the same test rating.

For the small amount of extra weight, I'd always recommend a 6 litre over a 3 litre.  By the time the operator has fired the first litre up their nose there'll be next to nothing left in a 3 litre.  I won't even mention the environmental issues. 

Standard fitment is as Anthony has suggested; 6 litre water spray for general class A risks; unless there is a specific class B risk, in which case it goes off the type, size and location of the class B risk as to what extinguisher(s) should be specified.
I wouldn't go so far to say that water jet extinguishers are 99% obsolete Anthony - warehouses with high racking would be a typical application or anywhere else you need a bit more range.  Having said that, last I looked, EN3 doesn't detail any discharge length (that strangely ended in BS 5423) but the old 4m-spray, 6m-jet figures seem to have stuck around.  I remember that caused a few red faces at the FIA when I pointed out that the question on their extinguisher technician course exam was wrong. 

I can't in all honesty think of an instance where a user wouldn't be able to manage a 6 litre extinguisher, therefore, would not consider a 3 litre under any circumstances.