Fire Extinguisher Redesign.

[Guest Chris Sargent.]

Hi there,
Im currently a final year student from Loughborough University studying 'Product Design and Technology'. For my final year design practice module I am looking to design an innovative lightweight household fire extinguisher and would be hugely grateful of your opinions.

I would love to know your opinions on the idea of a 'stylish' hand-held lightweight C02 based fire extinguisher for household use within the kitchen. In addition are there any problems with current models of extinguishers anybody has encountered at all? (price, usability, size, weight, etc.)

Thank you very much for your time. Im very grateful for each and every response.

Regards, Chris Sargent. (Loughborough University student)

[Safelincs]

Hi Chris

The idea of lightweight extinguishers is always attractive. However, I would stay clear of CO2 as an extinguishing medium for a general household extinguisher. CO2 is only suitable in quite restricted circumstances, as it does not penetrate fabrics, dissipates quickly and can cause asphyxiation in small rooms. Some type of foam or mist should do the trick. This would also avoid the design problems stemming from the high pressure in CO2 extinguishers (about 55 bar). CO2 extinguishers also have no pressure gauge, so a homeowner would never be certain whether the extinguisher is full!

For design ideas, have a look at the P50 Fireworld extinguishers made from aramid.

Harry

[green-foam]

Hello Chris, my 2p worth on the subject.

As Harry almost said, you can forget CO2 because for domestic use it is very limited, and as it is under such pressure it has to be in a heavy canister in order not to burst.

A popular miss-conception is the actual discharge time of an extinguisher.

http://www.youtube.com/watch?v=V_Nmf1cVPcY

From the above you can see that even a big 2kg CO2 extinguisher does not last that long, so even if you could make a smaller one, and if it could be used in a domestic situation it would probably last 2-3 seconds.

In your quest, for which I wish you luck, you should consider the following;

It needs to be not too heavy.

Easy to use

Suitable for more than one class of fire.

As an aside, "Recently" there was a spherical extinguisher about the size of a grapefruit, its no longer available, but you have to ask yourself why?

You may also like to know there are "aerosol" fire extinguishers available, in my opinion they are only of use if an ashtray is on fire.

[Guest Chris_Sargent.]

Firstly, thank you both very much indeed for replying and your suggestions to my post.

'Safelincs', it was interesting to learn of the C02 extinguishers quick dissipation rate. Considering how I had intended to have a one-handed, lightweight extinguishers this has lead me to rethink my idea.

You mentioned "foam or mist" but could you be more specific with this? Surely if you were to contain the foam or mist, although this might penetrate material, would the canister once again need to be highly pressurised, and this the canister would to be of a thick and heavy material?

"Green-Foam" thanks for your comments. I had looked for the grapefruit-like fire extinguisher and found the following concept... http://www.thisiswhyimbroke.com/throwable-fire-extinguisher
Although the actual artefact seems quite 'contained' and containing minimal packaging im not sure how a client/ customer would feel about throwing a 'grenade-like' object into the centre of their kitchen to put out a fire...

Your comments, and further research has led me into looking at rethinking the extinguisher from back to front - instead of containing the CO2 in a heavy duty container, could I in fact produce the C02 via a chemical reaction?

Thanks once again, any further comments would be very helpful indeed. Regards, Chris.

[Safelincs]

Hi Chris

I really like the idea about producing CO2 through a chemical reaction, although I am still doubtful about the CO2 as an extinguishing gas in general.

Water mist extinguishers have the same low pressure as ordinary water based extinguishers. They do, however, require far more gas than ordinary water extinguishers. For example a 3l water mist extinguisher comes as a 6l cylinder to contain the amount of nitrogen needed.

Please let me know how you are getting on

Kind Regards

Harry

[green-foam]

Hi Chris, The extinguisher to which I refer, you did not throw, it has a lever and handle, and it really was the size of a grapefruit, but also as I mentioned, it is no longer available, and regretfully I do not recall its name.

The other thing to consider, in particular with the video clip you linked to, if you notice the "whole room" is on fire, the idea of most extinguishers is to quench the fire before it gets too big.

Regarding making carbon dioxide (I don't know how good your chemistry is, so bear with me) its actually very easy.

You mix sulphuric acid with sodium carbonate solution. (Other variants are also possible)

This will produce carbon dioxide, at some pressure, but the volume produced depends on how much of each chemical you have to start with. By doing this you will end up with carbon dioxide and "water" (For the sake of argument) what can you do with the water now you have your carbon dioxide?

The answer has been around for many years,

No, it hasn't been photo shopped, this is a genuine 1961 soda / acid fire extinguisher.

As for carbon dioxide as an extinguishant its good, but not really suitable for the home, take a chip pan fire for example, if Joe Bloggs home owner were to point a carbon dioxide extinguisher at burning oil and operate the extinguisher, all that would happen is instead of one small fire there would now be multiple fires due to the burning oil being blown everywhere, like wise, burning paper can be put out by carbon dioxide, but only if the burning paper is in a container, if its not, the carbon dioxide can blow it everywhere causing more fires.

As Harry said, you would be better off with a foam or water mist.

http://www.youtube.com/watch?v=G67B1gMs8EQ

Water mist is good because it can be used on almost anything, and is 100% water.

Your main obstacle (and I still wish you luck) is finding something that will extinguish more than one category of fire and is compact.