The hazard
A fire extinguisher can stop a small fire before it spreads, but only if it is close by, charged and the right type for the fire. Fires grow fast, and smoke can fill a room before you know it. Knowing when to fight a fire and when to get out matters as much as knowing how to pull the pin.
The action
An extinguisher is for a fire in its beginning stage, the kind you can put out with a portable extinguisher without protective clothing or breathing gear. Before you fight it, make sure others have been alerted and someone has called the fire department, the fire is small and not spreading, smoke is not filling the area and your way out is behind you. If any of these is not true, or you are not sure you can handle it, get out and close the door behind you. (29 CFR 1910.155(c)(26))
ASK THE CREW
Who checks our extinguishers, and what do you do if you find one that is empty, damaged or blocked?
From the talk: Fire extinguishers. Read it in full, free, with the questions and the sign-in sheet.