Sentinel
Fire & Safety Equipment
Assessing your needs
Choosing the right fire extinguisher to suit your requirements is an important decision, insuring that it will be safe to use, appropriate to the types of fires you might encounter and cost effective .To achieve this end we hope the following information will assist you in making an informed choice.
Fires are divided into classes according to the material burning (fuel):
- Class A fires involve ordinary combustibles such as wood, paper, cloth, plastics, rubber etc.
- Class B fires are burning flammable liquids such as gasoline, paint thinner, oil, grease, acetone, solvents etc.
- Class C fires involve electrically energized appliances, tools or equipment
- Class D fires are burning metals such as aluminum, sodium, potassium, lithium, magnesium, titanium, zinc, and zirconium
- Class K, newly created in the 1998 NFPA to address the specialized problems associated with kitchen fires in deep fat fryers and grills.
Of course electricity does not burn, but the heat generated by short circuits, overheated equipment etc. can cause materials of Class A or B (or even D) to burn. Usually a class C fire is extinguished by turning off the electricity and attacking as a Class A B or D fire. This designation on an extinguisher label indicates only that it is safe for use on an electrical fire.
Class D fires are of concern to machine shops, labs and a few specialized applications. Some metals are violently reactive with water and other generate their own oxygen during combustion. Extinguishment involves an agent that encapsulates while the fire burns out.
Fires involving a combination of more than one class are not uncommon. The dry chemical (BC) and multi-purpose dry chemical (ABC) were developed to provide a general purpose reasonably priced answer to this need, and are the most common type in use today. They are available from three quarter to 20-pound sizes and available at least in the smaller sizes in less expensive non-rechargeable throwaway versions. A five-pound rechargeable unit makes a good home and office size at about $40.00 to over $50.00 (CDN).
Carbon dioxide units are rated for Class B and C fires and are most suitable for use in confined areas not subject to air movement. Unlike dry chemical they leave no residual mess. They are available in 2 lb. to 20 lb.sizes. Cost for a 5 lb. unit is about $125.00 to $150.00 (Can.). Maintenance cost are higher and pound for pound they are less effective than dry chemical.
Water filled extinguishers are most commonly available in a stainless steel 2.5 Gallon version . Water is the best extinguishing agent for Class A fires but this is the only class that it can be used on .This type must be located so as not to be exposed to freezing. Cost for this type is about $125.00 (Can.).
Halon and some ozone friendly halon alternatives are available as well. These, like CO2 preform best in confined areas. They are well suited to protecting sensitive equipment without the mess of dry chemical and the "cold shock " of CO2.
