Fire Extinguishers

A class "ABC" fire extinguisher. about $20 at any hardware store.

Class K fire extinguishers are potassium based, which react chemically with the cooking oil to produce froth. The froth rises from the bottom to the surface, and smothers the fire.

B on fire extinguishers generally means that it can be used to put out flammable liquid fires. B1 means it will do so, but not especially well (1 is the lowest ranking).

A is for flammable solids, C is for electrical fires.

Usually the number appears before the letter, so 1-B rather than B1. Properly used, a 1-B extinguisher can be reasonably expected to put out a puddle of flaming liquid about 2.5 square feet in area. If you've never had specific training in using one, you probably WILL NOT use it properly; for flammable liquid fires, unless it's an extremely small fire it's almost always better to call 911 than to try to use a fire extinguisher on it (you're more likely to spread it than extinguish it).

No. Some use a light yellow powder, but that is usually tri-ammonium phosphate, not sulfur

"foam" fire extinguishers are made for hydrocarbon fires...i.e: gasoline, diesel, etc. These fires are considered class "b" (flammable liquids), and are mostly used by professionals and in commercial and industrial settings. These extinguishers are charged with anther AFFF, FFFP, or AR-AFFF, however, these class of extinguishers are only rated class A & B fires and are hazardous to the environment, humans and animals in addition to being very corrosive.

15secs.

Anything other than water can be used on an electrical fire. These are often indicated on fire extinguishers as Class ABC or BC or even just C, where class C refers to fires caused by energized electrical conductors.

Water removes heat by converting into steam and may reduce the heat below the ignition temperature of the fuel. It may also INCREASE the ignition temperature of the fuel itself by soaking in. Thus, the fuel cannot continue to burn until all the water has been converted to steam, which requires more heat.

in a readily accessible location

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EXACTLY, if you see a fire, you need to be able to get at the extinguisher easily so it must be in an open area and not covered up or in a cupboard or storage unit. You could also consider where fires are likely to happen - near a cooker, by the engines etc. It is also a good idea to have one near a door so you can pick one up as you enter or leave a cabin.

Most often, simple fire extinguishers use sodium carbonate and dilute sulfuric acid to produce carbon dioxide, that extinguishes fire. small pouch carries the acid within a matrix of sodium carbonate. The pouch prevents the acid to come in contact with sodium carbonate outside. When the bottle is shaken, the two chemicals come in contact with each other, liberating carbon dioxide and water droplets that extinguishers.

Another type of fire extinguisher contains compressed Carbon Tetrachloride in it. When the nozzle is pushed, an aerosol of carbon tetrachloride is liberated that suppresses and extinguishes fire. This type has a major advantage that it can extinguish fires of oils, electric circuits, etc.

Other forms of fire extinguishers use forced water to extinguish fire.

Any class "A" fire. A class "A" fire is anything that when burned leaves an Ash.

by using two rocks and sharpening them together

With a dry chemical or CO2 fire extinguisher. Anything not conductive certainly not water.

Yes, carbon dioxide is found in some types of fire extinguishers. In others, nitrogen gas or compressed air is used. Some expensive types contain other pressurized gases such as Halotron or similar "clean agents" that leave no residue.

beware you need to get one that is designed for that type of fire using the wrong type could make things a lot worse

The best technique is to let someone who knows what they're doing do it. It's surprising to many people how hard a relatively small fire is to put out. When I was in graduate school we had a required fire safety class, and they set a 4 foot square pan of gasoline on fire and let us try to put it out. About half the class was not able to do so before their extinguisher ran out, and these were chemistry graduate students who understood the whole "how fire works" thing from a theoretical standpoint pretty well. Several people wound up blowing burning gasoline out of the pan, which obviously would have been really bad if the area around the pan hadn't already been cleared of anything flammable for a considerable distance.

For the record: aim at the base of the fire and sweep from side to side, not too fast and not too slow.

Not that that will likely help much; they told us all the same thing beforehand, and only about half of us were able to make it work anyway. The point they were making is that if a fire occured in your lab, unless it was trivially small, calling the campus fire department immediately was almost certainly a better use of your time than futzing about with a fire extinguisher.

Yes, under US and Canadian Coast Guard regulations, any vessel having an inboard engine (or an outboard with any closed compartments aboard) must have at least one Class B portable extinguisher, i.e., a USCG-approved B-I.

The main reason - is risck of electrocution. Water conducts electricity pretty easily. If the person extinguishing the fire isn't insulated, they could die from electric shock.

The most suitable extinguisher for electrical fires is dry-powder.

The first fire extinguishers were buckets filled with water or sand. In some towns, the fire warden would walk the streets at night and make sure every house had a water bucket on the front stoop, ready to be grabbed on the way to a fire.

You would not want to use a pressure water extinguisher on any electrical fire due to the possibility of electricity being conducted through the water and injuring someone.

A CO2, dry chemical or "clean agent" (e.g., "Halogenated") extinguisher would be a better choice for an electrical fire, knowing that dry chemical powder will make quite a mess.

No, not really. Fire extinguishers and fire blankets are used to stop fires. The "accident" would have already occurred, starting the fire.