Why are water fire extinguishers so popular in the UK when foam is more effective?

[Guest Manu]

I have seen in Uk the most common extinguisher apart from co2 is water ( foam is also common but not so common as water), water extinguishers are only for class a fires and seen them in offices, even restaurants, shops,etc. is very common to see combination of the classic 9l water + 2kg co2. BY contrast in Belgium and the Netherlands water extinguishers are not sold anymore ( modern water mi so foam extinguisher is the most common ( sometimes is rare to see co2 as they say foam is safe on electrical fires up to 1000v). Germany is not that different, though they sell water extinguishers, foam are the most common. Are different  country preferences a reason ? 

Thanks. 

Sincerely.

[Harry]

Hi Manu

Traditionally, in the UK, fire fighting points are split into two: one extinguisher for electrical applications (traditionally CO2, since powder has for the last few years been avoided indoors) and a water-based extinguisher for A-rated fire risks. Water-based extinguishers traditionally include water, water-with-additives and foams, especially AFFF foams. Strangely, there has always been a strong emphasis on the B-rating of foams, even though in 99,9% of offices, schools etc no B type risks are present (flammable liquids). This sadly resulted in a large amount of AFFF foam chemicals (strong on B type fires) being brought into circulation without benefit to the customer, which now have to be recycled very carefully.

Since the event of de-ionised water mist extinguishers a few years ago and the introduction of other electrically-safe water-based extinguishers the field has changed. It is now possible to have fire points with just one di-electrically tested extinguisher in most office and public environments. Minimum numbers of extinguishers overall, of course, still apply.

This trend is aided by the need to replace AFFF foam extinguishers with a more environmentally-friendly chemical in the next few months and years.

Harry

[Guest Manu]

Thank you, i thought class b was more common. foam extinguishers extinguish fires very well but as you said they have enviromental problems, however in some countries there is the possibility to buy ecologic foam extinguishers.

[AnthonyB]

Foam is actually far more predominant in the UK and has been for 30 years and is only just slowly changing.

There is a lot of history to this too going back to the 1980's. Extinguisher provision for flammable solids (Class A) is based around the the Class A floor rating (sq.m. x 0.065) using enough extinguishers to cumulatively meet the rating. The normal fire rating for a 9 litre water jet extinguisher was 13A, suitable for 200sq.m. per unit. However these were heavy and bulky and some companies wanted to use lighter 6 litre units, but these were only rated 8A so they had to buy twice as many. Also electrical equipment was becoming more and more predominant.
Enter the AFFF Foam Spray extinguisher, first developed in the UK in 1978/9  which from a 5.5l could get a 13A rating, meaning you could use a smaller easier to use extinguisher without needing to double up. It also had an 89B (later 113B & 144B) rating for flammable liquids and unlike the traditional water jet had passed the 35kV electrical conductivity safety test of BS5423 (our manufacturing standard prior to adopting EN3) allowing a margin of safety if used on electrical fires.
As a result it became popular as a lightweight multipurpose extinguisher, widely adopted in the 80's by several large companies & retail chains as well as British Rail and becoming the standard stock item of extinguisher service companies being installed as a standard item for A risks, regardless of any Class B risk.

The 90's saw the introduction of water spray (plain & with additive) extinguishers that also were able to achieve 13A ratings from smaller extinguishers as well as having the electrical conductivity pass - but the use of foam was so ingrained in the fire trade that they were slow to be adopted.

The environmental impact of foam (& the likelihood that fluorine free environmentally acceptable replacements to AFFF will be much more expensive) and phasing out of the commonly used foams means that water is making a resurgence and starting to become far more common.

The trade is slow to change though, hence why innovations such as Water Mist haven't taken off as much as they should.

The trade and it's influence on standards also explains the large number of CO2 extinguishers in the UK as unlike the rest of Europe they refuse to acknowledge that a EN3-7 35kV test pass means the extinguisher is safe to use on electrical fires up to 1000V allowing them to double sales by putting a CO2 with almost every other extinguisher.

If we followed the US approach you would just see Powder everywhere, but the UK has a history of using the best extinguisher for each fire class rather than a multipurpose approach.

[Guest Manu]

On 05/07/2022 at 20:00, AnthonyB said:

Foam is actually far more predominant in the UK and has been for 30 years and is only just slowly changing.

There is a lot of history to this too going back to the 1980's. Extinguisher provision for flammable solids (Class A) is based around the the Class A floor rating (sq.m. x 0.065) using enough extinguishers to cumulatively meet the rating. The normal fire rating for a 9 litre water jet extinguisher was 13A, suitable for 200sq.m. per unit. However these were heavy and bulky and some companies wanted to use lighter 6 litre units, but these were only rated 8A so they had to buy twice as many. Also electrical equipment was becoming more and more predominant.
Enter the AFFF Foam Spray extinguisher, first developed in the UK in 1978/9  which from a 5.5l could get a 13A rating, meaning you could use a smaller easier to use extinguisher without needing to double up. It also had an 89B (later 113B & 144B) rating for flammable liquids and unlike the traditional water jet had passed the 35kV electrical conductivity safety test of BS5423 (our manufacturing standard prior to adopting EN3) allowing a margin of safety if used on electrical fires.
As a result it became popular as a lightweight multipurpose extinguisher, widely adopted in the 80's by several large companies & retail chains as well as British Rail and becoming the standard stock item of extinguisher service companies being installed as a standard item for A risks, regardless of any Class B risk.

The 90's saw the introduction of water spray (plain & with additive) extinguishers that also were able to achieve 13A ratings from smaller extinguishers as well as having the electrical conductivity pass - but the use of foam was so ingrained in the fire trade that they were slow to be adopted.

The environmental impact of foam (& the likelihood that fluorine free environmentally acceptable replacements to AFFF will be much more expensive) and phasing out of the commonly used foams means that water is making a resurgence and starting to become far more common.

The trade is slow to change though, hence why innovations such as Water Mist haven't taken off as much as they should.

The trade and it's influence on standards also explains the large number of CO2 extinguishers in the UK as unlike the rest of Europe they refuse to acknowledge that a EN3-7 35kV test pass means the extinguisher is safe to use on electrical fires up to 1000V allowing them to double sales by putting a CO2 with almost every other extinguisher.

If we followed the US approach you would just see Powder everywhere, but the UK has a history of using the best extinguisher for each fire class rather than a multipurpose approach.

Thank you. Now i see the advantages of water extinguishers. You mentioned the " US" approach of using Powder (they call it Dry Chemical) i don't know why they don't use foam spray for indoor spaces ( as most of Europe does) it's very curious why different countries use different systems and approach, the best would be a homogenous system worldwide.

[Guest R-J]

Does anyone know why most 9 litre water jet extinguishers are now rated 21A rather than 13A. Have modern extinguishers become more efficient or has the testing standard changed?

[AnthonyB]

The test fire is the same and a plain water jet is a plain water jet. Operating pressures have risen slightly, but historically there was no need to push the test boundaries beyond 13A which was considered the equivalent of the old one 2 gallon water per 200 sq.yard rule from the pre rating days, whereas in more recent years a demand for higher ratings came in and as a 21A pass was generally achievable with a decent test operator so several manufacturers submitted models for the 21A test