What are Fire Extinguisher Ratings and Their Meanings?

Fire extinguishers come with different ratings dependent on the classification of fire they’re equipped for.  The rating of fire extinguishers is designed to help us understand the type and size of the fire in which the extinguisher should be used.

Classifications of fire vary and depend on the source of the outbreak or accelerant. They are:

  • Class A – ordinary combustibles such as wood, textiles and paper.
  • Class B – flammable liquid fires such as grease, oil, gasoline and solvents.
  • Class C – electrically energised fires such as computers and other electrical equipment.
  • Class D – flammable metal fires such as lithium and titanium.
  • Class K – kitchen fires caused in particular by fats and grease.

Class A and B extinguishers include a number with the rating; for class A the rating indicates how many gallons of water the extinguisher is equivalent to. For example 1A equals 1.25 gallons of water, therefore 5A would be equivalent to using 6.25 gallons of water to fight a fire.

A class B fire extinguisher takes into account the square footage of area a fire could consume as opposed to the water needed to put it out.  For example an extinguisher carrying the rating of 1B is capable of putting out a fire in a 1 square foot area. A 30B rating allows the user to extinguish a Class B fire in a 30 square foot area.

Knowing and understanding the rating behind fire extinguishers is vitally important in the event of a fire, although the most common extinguisher is the ABC.  This does have varying ratings dependent on its size, but can be used for A, B or C class fires, which would cover most eventualities within the home or office.

However, for larger premises you may need the help of an expert to determine exactly which kind of extinguishers you need.  Purchase advice, placement and maintenance of equipment is all part of the service that Swift Fire & Safety offer.

If you are need any advice on fire safety and extinguishers you can get in touch with us here.