Maximum area of class F fire (cooking oil) for which extinguishers are suitable

[deaconj999]

Can anyone please shed some light on the fact that according to this table for a fire with surface area of 0.4 m2 you would need 2 x 75F Fire extinguishers.

Have I go this right that a 20 cm x 20 cm surface area which just over A4 paper size you would need to have to hand 2 x 6 ltr wet chem extinguishers to put a fire out.

I am missing the point here I know, but I can't discover why, it seems I need 12 lts of extinguishing medium for a cooking oil fire with a surface are about A4 size.

[Tom Sutton]

Have I go this right that a 20 cm x 20 cm surface area which just over A4 paper size

GFSM I think your calculations may have gone a bit awry 0.4m₂ is a bit more than 400cm₂ more like 4000cm₂.

[nearlythere]

Have I go this right that a 20 cm x 20 cm surface area which just over A4 paper size

GFSM I think your calculations may have gone a bit awry 0.4m₂ is a bit more than 400cm₂ more like 4000cm₂.

.4 of a square metre is nearly half of it. So the surface area is around 1M x 1/2M ish which is around half the size of a desk which is around A1 ish size.
Fire ground calcs you understand.

[Golden]

This is where the metres squared and square metres becomes a too complicated for simple minds like mine but as far as I can see from the original post its asking for a fire with a surface area of 0.4m² - I see that as 40cm x 40 cm?

I obviously don't know about the depth of the tray and contents or if it has been pre-heated but two 6ltr extinguishers doesn't seem excessive - I'd imagine one 6 litres isn't enough and it could be a question that 7 litres would be sufficient rather than the 12 quoted?

[Tom Sutton]

I see that as 40cm x 40 cm?

Closer to 63.25 cm X 63.25. I think.

[deaconj999]

Have I go this right that a 20 cm x 20 cm surface area which just over A4 paper size

GFSM I think your calculations may have gone a bit awry 0.4m₂ is a bit more than 400cm₂ more like 4000cm₂.

.4 of a square metre is nearly half of it. So the surface area is around 1M x 1/2M ish which is around half the size of a desk which is around A1 ish size.
Fire ground calcs you understand.

NT, you are truly a genius, as I was having a wierd moment, my brain was stuck in reverse gear for a while, i haven't had to use the simple part of my brain for a long time to calculate something so simple. Thankyou for the kick start with your simple description, I'll have to go and see a doctor next time the cogs get stuck

[nearlythere]

Have I go this right that a 20 cm x 20 cm surface area which just over A4 paper size

GFSM I think your calculations may have gone a bit awry 0.4m₂ is a bit more than 400cm₂ more like 4000cm₂.

.4 of a square metre is nearly half of it. So the surface area is around 1M x 1/2M ish which is around half the size of a desk which is around A1 ish size.
Fire ground calcs you understand.

NT, you are truly a genius,

I know.

[Golden]

Thanks Tom; I'd read this as 0.4m x 0.4m whereas its (as you rightly point out) 0.4 x 1.0m which is 4000cm², the square root of 4000 being 63.25. Of course the guidance is written for any shape of container whereas I'd wrongly assumed a square/rectangle so it makes perfect sense now I actually think about it.

[deaconj999]

Good Job I asked then

[AnthonyB]

For any single risk that calculates as needing more than a single 75F extinguisher other than for travel distance/access issues I would consider that a fixed system is required.

Although if you look at the size of a 75F test tray you would be hard pressed to find a commercial fryer with a single compartment bigger.

Quite a few smaller establishments could suit the various 2 & 3 litre models available, which being cheaper are more likely to be installed, but whilst a lot of companies only push the mega 6 litre version (or don't do F class at all thinking ABC Powder, CO2 or non aspirated AFFF actually work)

This clip shows why powder extinguishers don't really do the business, using a real situation:
http://www.youtube.com/watch?v=X4GPxV_2vV0

[Tom Sutton]

They say " A picture is worth a thousand words " how true.