Some good info and some inaccurate info.
Class A is wood, paper, ordinary combustables
Class B is flammable liqueds
Class C is energized electrical fires.
Class D is burning metals.
A dry chemical, halon, halotron fire extinguisher is pressurized between 100 PSI and 195 PSI. A water fire extinguisher is pressurized between 100 PSI and 150 PSI. A CO 2 is pressurized to 700 PSI, bu the "snow" comes out at a low pressure. However, it you take the hose off, and discharge the CO2 extinguisher, you will realize there is a lot of pressure in the tank. The hose has a wire braid under the rubber cover. The wire braid conducts static electricity to the tank. If the wire braid is comprimised, enough static electricity can be generated to cause a spark to ignite flammable liqueds. A CO2 w/o a hose, 2.5 # or 5 # CO2 will generate enough static to be felt through your pants, especially on a cold day.
The water mist extinguisher is safe to use on energized electrical fire because pure water is not electrically conductive. Water w/minerals is electrically conductive. If a water mist is used, it must be recharged w/deioinized water. Amerex sells DI water to recharge the water mist FX.
If I have not completly bored you, go to How
Stuff Works then search for fire extinguishers.
fireguy
