Fire extinguisher points of interest- (Things I have learned from experience)
A fire extinguisher is only too big, if you can't run with it.
Small units are only useful, if you happen to be at the point where the fire originates, when it happens. Like a fire on the stove.
You can't put the fire out, unless you get in there close. No hand held dry chemical extinguisher will work from more than a few feet way.
If the fire is involved, electrical, or as a result of very high temperatures, as often the case with a vehicle, or piece of equipment, a dry powder fire extinguisher isn't the best tool for the job. Even if it seems like it did something, the heat that started it is still there, and it will often reignite. Water is the best way to reduce the temperatures and, be assured of it not reigniting.
And the most important rule they never tell you- Before you discharge a dry powder fire extinguisher, take a few deep breaths, and hold it. If you just ran to the fire, you are often gasping for breath, and you end up inhaling the dry chemical powder when you discharge the extinguisher. If this happens, you can forget about fighting the fire, because you will be coughing your head off, for about the next 10 minutes.