Dry Chemical (Class A, B & C Fires)
MULTI-PURPOSE DRY CHEMICAL FIRE EXTINGUISHERS USER GUIDELINES
Use for Class A, B and C Fires
What types of fires can be extinguished with multi-purpose, dry chemical extinguishers?
Class A fires which involve"ordinary combustibles" such as wood, paper, cloth, rubber and many plastics.
Class B fires which involve flammable liquids, oils, greases, tars, oil-based paints and flammable gases.
Class C fires which involve energized electrical equipment.
What is the proper way to use a Class ABC, multi-purpose, dry chemical fire extinguisher?
There are four basic operating steps. Think of the word "PASS" to remember the steps.
Pull the pin. Holding the extinguisher by the handle with the nozzle pointing away from you, pull out the pin located below the trigger. Note: Lifting the extinguisher by the handle will not activate the dry chemical stream.
Aim low. Standing up to 10 feet away from the fire. Point the extinguisher discharge horn at the front edge of the base of the fire (the lowest point of the fire nearest you). Remember - extinguishers are designed to be operated in an upright position. Always hold the extinguisher vertically. Never cradle it horizontally or at an angle in your arms. If the extinguisher is too heavy to hold properly, place on the floor next to you and operate.
Squeeze the trigger. Squeeze slowly and evenly. This action will release CO2 and expel it through the discharge horn.
Sweep from side to side. As the dry chemical is expelled, sweep the hose from side to side. As the fire closest to you goes out, you may move closer to the fire and continue the sweeping motion until the fire is extinguished. Continue discharging to prevent reignition. Remember, hold or place the extinguisher upright. If the fire does not diminish immediately, get out of the building.
How far will the stream of dry chemical reach?
The horizontal range of the dry chemical stream will reach a distance from 5 to 20 feet.
How long will it take to use up 10 to 20 pounds of dry chemical?
The approximate discharge time for 10 to 20 pounds of dry chemical ranges from 10 to 25 seconds.
Once activated, can an ABC extinguisher be turned off?
Yes, stop squeezing the trigger and the dry chemical stream will stop. This may be appropriate if you must reposition yourself in relation to the fire.
How does the dry chemical put out a fire?
The dry chemical works by blanketing the fuel (burning materials) and interrupting the chemical chain reaction at the fuel's surface. To a lesser extent, it dilutes the oxygen content of the air around the fire and absorbs heat.
What are the advantages and disadvantages of ABC, dry chemical fire extinguishers?
The multi-purpose chemical, monoammonium phosphate, is corrosive and damages computers and electronic equipment. The corrosive action may be slow and not evident for several months.