Posted By MP Grayson
By eck. You may regret asking this. There is no one simple answer. To give an accurate figure I would need to see your location, hazards, risks, other control measures, number of floors, numbers of fire exits etc, etc.
But you asked and you deserve a quick answer, so here’s a long one.
I would start by measuring the floor space for EACH floor and use this calculation.
Take the floor space and multiply by 0.065. So if your floor space is 20m x 30m = 600m2 x 0.065 = 39
Now look at the “A” rating found on any water, foam and dry power fire extinguishers that you have. Water is normally 13A, foam 23A (ish). And dry powder about 32A (ish). BUT they do vary considerably. I would then deduct those figures from the figure above. I am aiming for 0 or a minus figure.
So in example # 1. If you had x1 water @ 13A and x1 foam @ 23A your calculation would be
39 – 13A = 26 – 23A = 3
In example # 2. If you had three water @ 13A, the figure would be
39 – 13A – 13A – 13A = 0. Which is “Bob-on”.
The first example calculation leaves you an excess figure of 3, which means you are just over a quarter of a water extinguisher short. The obvious solution is to buy another water @ 13A which gives you a minus figure (-10). THAT is exactly what a fire extinguisher sales company will tell you to do and sell you extra fire extinguishers. Do you want that? Think about the extra maintenance costs. Unfortunately I cannot, (without looking at your premises) advise you what to do in that situation. Also do you need water, foam or dry powder? Or do you NOT need them? To get answer that question, you will need to look VERY closely at your fire risk (including number of floors, locations of exits and number of exits, carpets fitted, curtains, paper etc) and any other control measures. Also remember that you cannot use CO2 in the above calculation as it only has a "B" rating. And siting the extinguishers is another issue.
That should give you a basic start point. After that look at specific hazards such as flammable liquids and computers. That's when you start to introduce CO2 extinguishers and extra foam/powder on top of the basic requirements.
Deciding what fire extinguisher you want is also not that straight forward.
1. Foam? Great, but many people don’t actually know how to use it proper like. When using it on liquids you need to aim past the fire, bounce it off an obstruction and build up a blanket of foam which will work back and cover the fire. Squirt it directly at a liquid fire (class B) in the open and you just spread the fire all over the place. And it is not recommended for fires involving electricity.
2. Powder is the wonder stuff and it has a high “A” rating. But it can cost in other ways. You could for example use it to put out a fire that would cause £30 worth of damage, but by doing so you could cause £1000 worth of damage to your IT or other electrical equipment. The powder gets everywhere. Don’t use a vacuum cleaner to clear it up either, it wont last too long as the dust will get into the motor and “put it out”. Use water, scrapers and rags. Anybody breathing in the powder who suffers from asthma will have an attack. The powder is also very fine and it will penetrate the lungs and enter the blood stream. It is not toxic however; it is a VERY, VERY POWERFUL LAXATIVE. I would not recommend taking a sleeping pill that night. ;-o
Apparently I can charge up to £400 for training and fire risk assessments etc. (a man on the telly said so last night). So if you need a hand………….You also get a free COSHH assessment for the dry powder.
Anyway. I must fly. I filled the washing up bowl with hot soapy water and placed a little surprise into it. I need to see if the current Mrs G has found it the hard way
Crack on.