There are four classes of fires. All fire extinguishers are labeled, using standard symbols, for the classes of fires on which they can be used. A red slash through any of the symbols tells you the extinguisher cannot be used on that class of fire. A missing symbol tells you only that the extinguisher has not been tested for a given class of fire, but may be used if an extinguisher labeled for that class of fire is not available.

Types of Fires:

• CLASS A: Ordinary combustibles such as wood, cloth, and paper.
• CLASS B: Flammable liquids such as gasoline, oil, and oil-based paint.
• CLASS C: Energized electrical equipment, including wiring, fuse boxes, circuit breakers, machinery and appliances.
• CLASS D: Combustible metals such as magnesium or sodium.

Portable extinguishers are not designed to fight large or spreading fires. Even against small fires, they are useful only under certain conditions:

• The operator must know how to use the extinguisher.
• The extinguisher must be within easy reach, in working order, and fully charged.
• The operator must have a clear escape route that will not be blocked by fire.
• The extinguisher must match the type of fire being fought. (Extinguishers containing water are unsuitable for use on grease or electrical fires.)
• The extinguisher must be large enough to put out the fire. Many portable extinguishers discharge completely in as few as eight to ten seconds.
• Always be sure the fire department inspects the fire site, even if you think you've extinguished the fire.

The standard rule of thumb is a travel distance of no more than seventy-five feet for Class “A” hazards and fifty feet travel distance for Class “B” hazards.

These are general guidelines and can differ based on many factors. Fire Extinguisher spacing is addressed in NFPA 10 (Standard for Portable Fire Extinguishers) section 6.2.1.1.

It is the owners’ responsibility to inspect the fire extinguishers at a minimum of thirty day intervals. Fire extinguishers shall be inspected at more frequent intervals when circumstances require.

Fire extinguishers shall be subjected to maintenance at intervals of not more than 1 year, at the time of hydrostatic test, or when specifically indicated by an inspection or electronic notification.

Maintenance Record Keeping: Each fire extinguisher shall have a tag or label securely attached that indicates the month and year the maintenance was performed, identifies the person performing the work, and identifies the name of the agency performing the work.
 

All fire extinguishers have a "Born On" date. On the chrome liquid types, that date is usually found on the hanger loop. On the reqular ABC, BC, or Halon extinguishers that date is uaually found on the label, however some manufacturers stamp the date in the "boot" located around the extinguisher base. Some manufacturers stamp the date in the bottom. On the CO2 type extinguishers this date is found stamped around the shoulder near the top.

All dry chemical type extinguishers as well as water based and CO2 brought in for 6yr maintenance, hydrotest, or recharge will have verification collars attached as proof of depressurization, devalving, and internal maintenace.