How and when should a fire extinguisher be used?
You take the hose and you click a button and the stuff flies out.
The chemicals in a fire extinguisher will normally not hurt you in an open area (remember some displace the oxygen to put out the fire.) However the danger comes when someone plays with a fire extinguisher and puts it back with out recharging it so it can NOT be used in an emergency. Fire extinguishers are not toys and should be handled only in an emergency.
Yes, it is illegal in any state to discharge a fire extinguisher unless used to put out or control a fire or used in demonstration. The law comes in to effect when the fire extinguisher is not at capacity and can hinder the safety of it's purpose. To discharge a fire extinguisher for any other reason is criminal, states very on it's punishment.
Depending upon what fire code is used and where the extinguisher is located, it should be checked monthly. In fact, a fire inspector can ask to see the records of the monthly tests, which are normally attached on a tag on each extinguisher. Modern codes are beginning to require automatic electronic monitoring of fire extinguishers.
Fire extinguishers are designed and constructed to put out a fire. The term used here is fire extinguisher, and a fire extinguisher is applied to extinguish (put out) a fire. It's that simple. Naturally there are different types of extinguishers for different applications, but other questions here speak to that.
The only kind of fire extinguisher that should be used in the kitchen is a class "K" rated and listed extinguisher because it is effective on cooking oil fires. The only available BCK rated and listed (A-B-C-D-K effective) residential fire extinguisher is FireStopper® PFE-101, PFE-102, & PFE-1LR. For more information see related link below.
A gasoline fire is a "flammable liquid" fire, and you would use a Class B (or ABC or BC) fire extinguisher. For example, if there were 5 square feet of flaming gasoline, you would need a 5-B:C extinguisher to be able to put it out safely. Using water (e.g., a 2A pressurized water extinguisher) would be a "bad idea" because it may simply spread the flaming liquid and make a bigger fire.
One of the biggest dangers associated with fire extinguishers comes from using the wrong type of extinguisher to fight a fire. For example, a water extinguisher used on electrical or oil fires can cause electric shock or explosions. A Type B or C carbon dioxide extinguisher used on a chemical fire may cause violent explosions that lead to İnjury or death.