Fire Extinguishers

The fire extinguisher closest at hand may not be the right one

Fire ExtinguisherFire extinguishers are the most commonly used form of flame/fire retardants in the workplace. The labeling of fire extinguishers has been changed these days to show pictorial symbols instead of letters, and a multi-purpose unit will have more than one picture to symbolize its abilities. Unfortunately, there is no symbol for Class D.

What could be more critical to workplace safety than the vital issue of fire prevention? And naturally, we cannot rely on smoke alarms and sprinkler systems to keep us safe.

The location of fire extinguishers in your workplace is critical, since most people grab the nearest one, assuming that it's suitable for the fire at hand. Not always so.

For example, since Class D fire extinguishers are designed to put out fires involving certain types of metal, this kind of extinguisher must be located close to the metals in question. And Class C fire extinguishers are critical for assuring electrical safety in the workplace, whether it's in the field or office.

There are five different classes of fire extinguishers. Look around your workplace - office, factory or commercial facility - to be sure the right classes of fire extinguisher are located in the right area(s).

Classes of fire extinguishers

  • Class A (water, chemical foam or dry chemical): used against combustible materials such as wood, papers and some plastics. The numerical rating attached will indicate the capacity of water in U.S. gallons which will be from 1 to 40.
  • Class B (halon, carbon dioxide, aqueous film forming foam or dry chemical): used against combustible or flammable materials such as gasoline, oil, grease and kerosene. The numerical rating represents the square feet of fire it can extinguish and will be from 1 to 640.
  • Class C (carbon dioxide, halon or dry chemical): used against electrical fires where live current remains a danger. The extinguishing agent is non-conductive, and Class C units do not have a numerical rating.
  • Class D (dry powder - suitable for metals involved): used against combustible metals such as magnesium, titanium and sodium. Type 1 (sodium chloride) and Type 2 (copper-based powder); neither type of Class D has a numerical rating.
  • Class K (potassium acetate based, low PH agent): used against cooking oils. Class K units do not have a numerical rating.
  • Multi-purpose extinguishers are known as Classes BC, ABC, AC and AK.

The labeling of fire extinguishers has been changed these days to show pictorial symbols instead of letters, and a multi-purpose unit will have more than one picture to symbolize its abilities. Unfortunately, there is no symbol for Class D.

The Occupational Safety and Health Administration (OSHA), the National Fire Protection Association (NFPA) and American National Standards Institute (ANSI) each have their own guidelines for fire prevention and protection.

Something to keep in mind: the bigger the fire extinguisher, obviously the larger the fire you will be able to combat - but a heavier extinguisher also makes it more difficult to move around during a fire.

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