A Fire Extinguisher Buying Guide for Greene County Businesses

6/6/2022 (Permalink)

Every business in Greene County should have fire extinguishers to suppress minor fires. This buying guide identifies the main classes of fire extinguishers and explains why a multi-class may be ideal for commercial use.

Extinguisher classes

Extinguishers are classified by standard NFPA 10 set by the National Fire Protection Agency. Suppressants are selected for effectiveness and safety:

• Class A extinguishers contain monoammonium phosphate and work on ordinary combustibles such as wood and paper
• Class B extinguishers contain monoammonium phosphate and work on flammable liquids and gasses, but not grease and cooking oil
• Class C extinguishers contain monoammonium phosphate and sodium bicarbonate and work on appliances or powered electrical equipment
• Class D extinguishers contain sodium chloride or copper powder and work on combustible metals such as magnesium
• Class K extinguishers contain potassium compounds and work on fats, cooking oils, and grease

These classes form the backbone of fire extinguisher classifications and the distinctions have important implications for firefighting. For example, using a CO2 or water extinguisher on burning metal can have disastrous consequences.

The letters on a fire extinguisher’s label indicate which classes of fire it can effectively fight. For example, an extinguisher marked “1A:1B:C” could extinguish Class A, Class B, and Class C fires—if it’s big enough to tackle the blaze.

That’s where numbers come in. The numbers preceding the letters on the label indicate just how much fire the extinguishing agent—the powder, gas, or other fire-fighting material–can put out. As part of a fire extinguisher’s classification, the numbers on the label can mean either:

• How much water would be required to match the agent’s power against Class A fires
• The square footage of Class B fires the agent can extinguish

For each A, the extinguisher contains the equivalent of 1.25 gallons of water. Thus, an “8A” extinguisher fights Class A fires as well as 10 gallons of water (8 x 1.25 = 10), and a 40A extinguisher offers 50 gallons’ worth of firefighting power. For each B, the extinguisher can stop one square foot of Class B fires. A 10B extinguisher can stop 10 square feet of Class B fire, a 20B extinguisher can stop 20 square feet, and so on.

What the letters and numbers for Class C, D, and K fire extinguishers mean

Class C fire extinguishers: electrical fires

Extinguishers with the power to fight electrical fires do have a “C”—but it’s never preceded by a number. All class C fires are just Class A or Class B fires with electricity added into the mix. The letter “C” indicates only that the fire extinguisher uses an agent that doesn’t conduct electricity. Water-based and some foam extinguishers can’t fight Class A or Class B fires involving electrical equipment (thus, no “C” on the label). But extinguishers that use inert gases and various powder mixtures can, meaning they have an “A:B:C” rating.

Class K fire extinguishers: oils, fats, and greases

These labels treat Class K fires (kitchen oils, fats, and greases) in much the same way. Extinguishers that can fight Class K fires may have the letter “K” on the label, but they won’t have a number. That’s because Class K hazards vary enormously. The same volume of solid fuel (say, charcoal) may require significantly more extinguishing power than liquid fuels (like deep fryer fat).

Rather than trying to give Class K extinguishers a uniform rating, the International Fire Code and other fire safety standards recommend sizes based on a kitchen’s specific hazards. And in some cases—such as when deep fryers with an especially large surface area are used—it’s up to the manufacturer to provide guidelines.

Class D fire extinguishers: metal fires

While they’re required to be listed and labeled, purchasers can’t simply rely on the letter “D” to indicate an extinguisher’s suitability against metal fires. Like Class K hazards, one Class D hazard differs from another. The subject is so complex that the National Fire Protection Association (NFPA) has a whole standard just for combustible metals. Some Class D agents stop one type of metal fire, while others can take on several. And even agents suited to multiple fire types will perform better on some types of metals than others.

Which should you choose?

Many cities and states require fire extinguishers with a minimum UL rating of 2-A:10-B:C in buildings. Check with the Greene County fire authorities for the commercial building code requirements in your area. When it comes to size, your primary considerations should be size and heft. Units that are too bulky and heavy are useless. Choose fire extinguishers that any employee could handle with ease.

If your Greene County or Springfield business suffers a significant fire, contact the fire restoration professionals at SERVPRO of Springfield / Greene County immediately! We’ll restore your commercial property quickly to reduce any loss of income and productivity.