The dry chemical is basically baking soda, that releases CO2 when it gets hot. It just leaves a really nasty mess to clean up after the fire is over. Before all the flap about chlorinated hydrocarbons, there was an extinguisher medium called "Halon" which was less expensive and lighter weight than CO2, but it evaporated on contact. I don't know if it's still available.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!