Dry Powder as standard

[Meerkat]

Having looked at a number of specifications for new and extended industrial buildings outside the UK recently I see that in almost every case the designers are specifying solely dry power extinguishers throughout the site.  I realise that this is probably cost driven - i.e. "one extinguisher does everything"

I'm not convinced by this - mainly becasue of the mess that dry powder makes of electrical equipment and also what I would see as its failure to effectively extinguish contained flammable liquid or oil fires.  In the UK I would normally look at a combination of carbon dioxide and foam extinguishers (as appropriate to the area) with DP only where justified - for example for a quick knock down near flammable liquid stores where there is a theoretical possibility of a running liquid fire.

I'd be interested to hear what any of our extinguisher experts think of the "dry powder does everything" approach and whether others are seeing the same thing.

[nearlythere]

A smallish cafe (60 seats) I have been involved with recently had a small fire in an electrical box in the public area and, according to the owner, happened all of a sudden and scared the kack right out of him.
However, he had the presence of mind to grab the nearest extinguisher which was located in an open cooking area and successfully used it to extinguisher the fire.
It was a DP and he had to close up for three days after and pay the staff to clean up the mess.
He may have successfully extinguished the fire with the DP but a CO2 would also have been adequate and would not have cost him 3 days lost trade.
DPs may have their place but in a small cafe?
It seems to be the done thing for some extinguisher providers, as soon as they see a cooker and pan, to think DP.

[Midland Retty]

Hi Meerkat

Im certainly not an expert but would agree that all too often DP extinguishers are specified without a thought given to the environment and type of fire they may be used in /on.

From memory some of the problems with DP include:-

1) The Mess - also note that certain powder media can be or become corrosive thus causing damage
2) When expelled the powder can obscure visibility during firefighting (especially in confined space)
3) May cause breathing difficulties for user / other people (again if used in confined space)
4) No cooling effect on fire, thus re-ignition can occur in some circumstances
5) Although can be effective on running liquid fuel fires but this requires specialist training (used in conjuuntion with AFFF).
6) Not effective outdoors on a windy day !!!!!

[BLEVE]

Have seen DP installed within hospital wards including an ITU. Had them replaced immediately. Not a good idea considering hazard of reduced visibility and respiratory irritation on discharge in a ward of 15 non ambulant patients.

They have their place and are effective when matched to hazard and location.

On a similar theme have also encountered a number of DP automatic extinguisheres mounted at the end of a chain (not good)

[AnthonyB]

It is a peculiarity of the UK that we routinely have multiple types of extinguishers in places so that the best for each risk is provided.

Go to the USA or anywhere in their sphere of influence, or most of Europe and the 5lb & 10lb ABC powder (or Europe the 6 kilo) is the standard for 99% of premises with only specialist risks (such as Class K, the US version of Class F) having to use other types (was BC Powder, now only wet chemical)

As stated on this forum many times Powder is Jack of all trades, but master of none. It's original design aim (in the days of BC power) was to provide an extinguishing agent capable of the rapid extinction of class B fires involving shallow spill and/or running liquid fires and the rapid knockdown of fuels in depth prior to the application of a foam blanket.

In essence this still is the main reason for Powder - it has other applications but it's not best suited for that.

People who see a cooker or fryer and think Powder are showing their ignorance and incompetence as due to the chemistry involved the acid Ammonium Phosphate of ABC Powder (now in 99% of extinguishers) has no effect on cooking oils so once the powder has gone the temporary effect of inhibition will pass and the oil, still at autoignition temperature, will continue to burn. The original use of Powder in kitchens was because back in the day when 99% of powder extinguishers were alkaline sodium bicarbonate BC Powder - this did have a saponification effect on the actual oil (not as much as Wet Chemical) and would control it if you put enough on (hence why before Wet Chemical US codes stated that only BC powder extinguishers of a specific minimum rating could be installed in kitchens - no ABC)

I've seen a slight increase of Powder installs in situations where people should have known better, resulting in later replacement.

[Meerkat]

Thanks Anthony - great answer!

So that's why people from overseas look at me funny when I try to convince them to replace the DP with a combination that makes sense according to the risk then....  Has anyone succeeded in convincing overseas designers that this isn't just a weird requirement from the UK?

[AnthonyB]

My contemporaries from over the pond who are in the extinguisher field and members of my Facebook group agree that Powder isn't perfect.

But the US is more code obsessed than us and more to their point the codes are backed up in name by statute, whereas our British Standards aren't so directly cited in law and it's more of an allusion that you should comply to meet the law - there you MUST.

I'll ask if they know of anywhere that they've succeeded in installing a more UK type of extinguisher mix.

[Meerkat]

My two recent experiences of this have been in Eastern Europe (EU Country) and China.  In each case the designer / local Project Manager thought I was mad...  Mind you they had some very weird ideas about NFPA sprinkler codes too 

[John Webb]

I'm not certain exactly where the previous discussion lurks, but the drawback of powder needing clearing up was highlighted by the Ecclesiastical Insurance Office (EIO) when they had to fork out some £250,000 to one of their churches several years ago when there was a malicious discharge of a DP extinguisher in that church. The organ had to be dismantled for cleaning and scaffolding put up to remove the powder from stone ledges and the like to prevent long-term damage.
As a result EIO instructed all their insured properties to remove DP extinguishers and replace with ones appropriate to the risks present....

[Psuedonym]

I reckon the distribution of a portable should follow a Common Sense Risk Assessment. Not a "one does all" approach or " the insurer said to use this.."
As we know powder is a nightmare and always will be a balance of good fire safety and resulting chaos and cost after the event and this should be explained to a client along with any selling or advice. Along with a bit of training this would then give the client a little product knowledge so as to allow him to make an informed decision.

I just got back from Italy - apparently in the EU, and every single portable I, er, happened to glance at, was a powder!! Differing models, colours, sizes etc etc but still ABC all the same. So much for EU standardisation! Is it just the UK that bother with fire training or safety???

[nearlythere]

So much for EU standardisation! Is it just the UK that bother with fire training or safety???

There are empires to build and maintain Psuedonym and the UK excells in that area.

[AnthonyB]

Most of Europe is heavily Powder oriented, although France did have a variation of types in common use, usually water spray with additive (AFFF spray, as these are A/B rated) & CO2.

[Meerkat]

Continuing the theme...  As some of you will know I've been looking at a small 2 storey B&B recently for FRA and was considering the provision of extinguishers (or not!)

I don't want to get too hung up on what the Govt guidance says but it recommends "suitable multi-purpose extinguishers .. available from DIY shops

If you Google "multi-purpose fire extinguisher" almost every result is for a 1 or 2 kg dry powder - even Argos sells them!  Now would you really want to set one of these off inside your house?    Would you really want extinguishers anyway to be honest since your plan is to get everyone out! (that's a more or less rhetorical question as I'm going to recommend them!)

There was one Google result in the first two pages that wasn't DP and that was for  a 2 litre ABF foam.  I was thinking something like this in the access areas and possibly a carbon dioxide in the kitchen.  What is it with the fixation on powder.... 

[kurnal]

As you probably are aware the Lacors guide also recommends a "simple multi purpose extinguisher" in the common areas of flats and HMOs.
It does not define what type of extinguisher falls into this description but inevitably the outcome is dry powder. Affect on tenability and visibility within the escape routes especially in untrained hands?

The one thing you can say in their favour are that they have rapid initial knock down even in untrained hands.

[AnthonyB]

Since the demise of Halon, ABC Powder has generally been the only thing left that also had an A,B & Electrical rating.

However, creeping into the market are the latest chemical agents that have good all round capacity, the 'ABF' Foams. These are rated for A, B & F fires (unlike Powder) and also have passed the 35kV di-electric test with some insultingly being marked as safe up to 1000V at 1 metre.

These would form a far better basis for cover. If you used these you wouldn't need the CO2 in the kitchen as CO2 isn't suitable for Class F fires and the ABF Foam has 1000V approval.

Also you can get a 2 litre AB rated foam now with a 13A rating that gives you equivalency with a 2 kilo Powder, also having passed the 35kV test.