quote:
Originally posted by Navyreg1970
Dry powder is usually something along the lines of baking soda - not in its self toxic but it will make you splutter and choke.
I was trapped in an engine room fire on my last ship - in the bilge under the shaft brake when that caught fire. Couldnt use water as it would make the brake pads explode due to the heat - dry powder was the only option - it was fired down onto me, i absolutely couldnt breath at all as one breath of it coated my lungs - however i got out and managed to cough / puke it all up and there seems to be no long term damage. So its only dangerous in so much as it chokes you.
Fire needs three elements - heat, oxygen , fuel. Remove any one and the fire will extinguish
Dry powder works by excluding oxygen from the fire. It is good on oil/fuel as it will smother the liquid but its downside is that it doesnt cool so if the liquid is disturbed suddenly revealing a gap in the powder layer it will let oxygen back onto the fuel surface then it may well re-ignite. If you have a dry powder extinguisher - bang it down on the floor before operating as sometimes if it has been sat for a very long time the powder can form a solid lump in the bottom and all you will spray will be compressed air/nitrogen depending on brand. It goes bloody everywhere but at least you can hoover it up
Next option - water, not good in a workshop as on an oil/fuel fire it will cause a fireball but is good on carbonaceous fires such as paper, dirty rags etc. remember electricity will track back up the water jet up to 2m (based on 240v)so if using a water hose where there is a risk of electricity try to bounce the jet off a metal object such as a metal roof or any large earthed metal object to reduce the risk of you getting a zap.
CO2 - good for electrical fires, not good on paper as it tends to blow it everywhere and may spread the fire - real care would need to be taken if using on a liquid fire as if you spray it too close it may splash burning fuel everywhere.
Foam (Aqueous film forming foam - AFFF) the most versatile of general purpose extinguishers, good on liquid fires but dont blast it into a liquid fire, try to get it in at an edge and let the foam roll over and smother the surface - also provides cooling. Same electrical precautions as for water
We used to charge our own extinguishers on the ship - one mug of foam solution to 9 ltrs of water, screw the top on and pump up to 10bar.
I would get a dry powder and a foam - i would not get a car dry powder as theres just not enough in there. The secret to minimizing the chance of a workshop fire is meticulous cleanliness and correct storage of flammables. A spark from a welder cant set fire to an oily rag thats not there!
The Dog is on its way....
Nice one Lee. This is really usefull;-)
HAHAHAHAHAHAHAAHAHA!!!
