Wet chemical extinguisher provision

[TFEM]

With due consideration to the new 5306 Part 8, I wish to advise my customers correctly.

Would you treat a 3 pan deep fryer as one risk or would it be regarded as 3 individual risks (each pan having its own thermostat).
The overall area exceeds 0.4m2 but individually the pans don't.
Would my recommendations then be based on one of the three pans on the assumption that all 3 are unlikely to ignite at once?

Further, the new standard states that "types of extinguishers other than those suitable for class F fires should not be sited in areas where cooking oils or fats is the major factor in the risk analysis". This is then complicated by 8.6.3 stating "in areas protected by fixed systems, portable extinguishers should be provided to cover the risk of spillage or fires originating outside the coverage of the fixed equipment". Wet chemical extinguishers are not suitable for spillage fires, neither is foam. Powder is suitable but not advisable. Presumably therefore the existing CO2 is OK?

Thanks for your views in advance.

John

[lancsfirepro]

Morning John,
My personal opinion on this is that separate fryers having separate heaters and thermostats are unlikely to go up simultaneously.  Further a fire in one would be unlikely to set off a fire in another (unless it has been burning for a while) because the oil needs to reach temperature to sustain combustion.  For these reasons I would consider them as separate risks.  Bear in mind that a fixed system covering the three fryers would initially be triggered above the first fryer that went up - the contents would then be fully discharged into that fryer, thereby leaving nothing for the others.  So yes, I would consider the risk of one.

As far as your second question goes, regardless of the points you made, section 8.6.3 is titled "Additional extinguishers to the minimum scale of class F provision".  As it only refers to class F provision, then that's your answer.  It doesn't offer any guidance as to the level of provision though.  It states "portable extinguishers should be provided" so may suggest more than one is required but as it offers no guidance you'll have to apply a bit of common sense.

[AnthonyB]

A spillage of cooking oil can be extinguished by Wet Chemical, I've seen it done, it's not going to be a flowing fuel fire, usually a bit of splash over.

With the dynamics of how these fires develop I'd agree that only one pan would be expected to ignite in a particular incident certainly in the  'first aid' stage.

Unlike the US who are a bit more strict with the need for fixed systems, portable wet chems there being only as a back up after discharge of  the fixed, it's not uncommon for even large kitchens and ranges to have portable only cover so correct provision is essential.

A kitchen need only have a Wet Chem for the cooking area with a CO2 as well in the room for electrics (don't forget Wet Chems are A and increasingly as well B rated, plus have passed the 35kV test) I've seen some that have had a fire point with literally everything there - water, spray foam, ABC Powder, CO2, Wet Chem, fire blanket and an Ansul Pull Station - total madness!

[John]

Wouldn't it just be simpler, and cheaper, to install a couple of 6 litre water mist fire extinguishers which carry a 13A and 75F rating, and are also suitable for use on fires involving live electrical equipment or recently energized electrical appliances ?

Just a thought 

[lancsfirepro]

I draw your attention to this section of BS5306-8:2012 

[AnthonyB]

John, You are Jewel Saffire and I claim my five pounds!*

As indicated above the UK has not adopted the mainland EU path of permitting wets that have passed the 35kV test to be installed for direct electrical use, hence why all but a couple of manufacturers do not put the 'electrically safe' pictogram on extinguishers.

You could follow the EU route in your risk assessment and install them for use up to 1000V but you would have to justify it (there is precedent - British Rail used AFFF spray to replace both water and halon in 1990)



* for those too young to understand the line... http://en.wikipedia.org/wiki/Lobby_Lud

[John]

Anthony,

I am nothing to do with Jewel Saffire (and I hope and pray that another mainstream manufacturer will develop their own water most extinguisher very soon), so I hate to break it to you, but there will be no fiver 

Anyone mentioning conductivity testing for water spray extinguishers clearly does not understand the principle of water mist delivery.  The clue is in the title, water MIST.  The medium is not a stream of fluid, and it is not a spray, where a stream of fluid is partially interrupted.  In addition to this, to be even more sure operators are at no risk from conductivity, demineralised water is used in the filling process.

[lancsfirepro]

Morning John,
Never fear, we do understand the concept of conductivity through a stream, spray, mist etc.  The point I was making was that we need to be seen to be adhering to the accepted guidance when specifying and installing extinguishers.  At present, that guidance states that we should not provide water based extinguishers for electrical risks.  The risk is not that the user will be electrocuted via the discharge path but more likely through their feet should the floor become wet.

I for one will not be specifying water mist extinguishers for the simple reason that I cannot see a use for it over what we already have.  Possibly as a replacement for a wet chem but the water mist is more expensive and does not prevent re-ignition like wet chemical does.  It really has no real-world use.... certainly not at that price point anyway.
I spoke to JS and suggested that maintenance companies would not be likely to refill a water mist with distilled water when they could fill it with tap water and they said it would still work regardless.  As they say in Dragons Den.... I'm out.

[AnthonyB]

If you were in the US you would have no problem selling mist extinguishers for live electrical use - Amerex's water mist extinguisher (around for over 20 years) is Class C* approved.

However in the UK it is not marked 'electrically safe' because although it passes the 35kV test (which is an EN3 test and it matters not if it is a mist or a spray) the manufacturer accepts the British version of EN3 and BS5306-8 which says wets should not be specifcally marked for direct use on electrical fires.

If we had followed the way EN3 had been implemented in many other European counties, not only would the mist extinguisher be marked with the 'electrically safe' symbol so would all the cheaper spray extinguishers (some are already)

[lancsfirepro]

If you haven't seen this, you've gotta...  https://www.youtube.com/watch?v=8AYZCe5tj-8

[AnthonyB]

Yes, a classic. I don't know why it's listed as a water mist on Youtube, it's more like an AFFF spray or catalytic agent spray.

[lancsfirepro]

Just love the attitude over there... "You there!  Take your shoes and socks off and start paddling and praying."  Saw a Chinese guy discharge testing some 5kg CO2s a few years ago - he kept getting shocks due to the discharge.  Now that was funny.

[Psuedonym]

Morning John,
  Bear in mind that a fixed system covering the three fryers would initially be triggered above the first fryer that went up - the contents would then be fully discharged into that fryer, thereby leaving nothing for the others.

Just to confirm - a fixed system is total discharge. ie. appliances' surface area, plenum length and duct/s area dependant. Therefore the whole areas are protected to stop the spead of a fire and ensure restart is impossible - designed originally for fryers/bratt pans, all appliances beneath the hood are protected by type specific nozzles ( non flowing liquid grease undergoes a process called saponification).
discharge is achieved by the fixed temperature detection links within the plenum splitting releasing the tension wire and mechanically operating the system. This discharges over everything and within the plenum/duct areas. As an example have a look at an Ansul R102 youtube video for clarification.
Using a portable on a fryer is exstremly dangerous regardless of any companies staff training (hate to say it but dp is the best for portable use followed with afff/wet chem). The red hot burning fats spill out and spit out from the surfaces and the huge temp makes the approach difficult even with a wet chemical lance.
As for a fire blanket - forget it unless you want serious injury...oh silly me I forgot   ... Chubbs blankets are of course safe. (See the picture on their fire blanket box - the chefs leaning over a burning pot on one version)  

[AnthonyB]

I'd not put much hope on powder, being acidic you get no saponification and just very temporary knockdown whilst you are discharging due to inhibition and non aspirated spray AFFF will just burn off and evaporate.

Now go back 30 years when powders were bicarbonate based and foams were aspirated FP you would stand a fair chance.

Powder and foam don't have class F marking for a reason.

However the best route to dealing with Class F is the US way - you must have a fixed system which is always the primary mode of attack and the wet chem portable is strictly back up only - far safer

Chubb are one of the few manufacturers to actually state on their blankets they are not suitable for risks involving over 3 litres of fat and/or containers over 300mm diameter - i.e. nothing beyond a chip pan.

http://www.youtube.com/watch?v=fYlQDAyR-ME

http://www.youtube.com/watch?v=e_8L01otbn4

(I can't find the best clip which shows a fire department in a real situation dumping 3 or 4 20lb ABC and a 10lb CO2 at a real incident with no success)

[lancsfirepro]

How many companies supplying Wet Chemical extinguishers actually instruct the client how to use one and what to expect when they do use one?  They need to expect a degree of flare up upon first application so they don't think "hmmm, this is making things worse" and stop using it.