The dry powder in a dry powder fire extinguisher is ammonium phosphate, sodium bicarbonate, sodium chloride, potassium chloride dry powder fire extinguishing agent.
Dry powder fire extinguishing agent is used to extinguish the dry and easy to flow micro-fine powder, by the fire-fighting efficiency of inorganic salts and a small number of additives by drying, crushing, mixing and become micro-fine solid powder composition. It is a widely used fire extinguishing agent in the fire, and mainly used in fire extinguishers.
In addition to the special dry powder chemical extinguishing agent to fight metal fires, dry powder extinguishing agent is generally divided into BC dry powder extinguishing agent (sodium bicarbonate, etc.) and ABC dry powder (ammonium phosphate, etc.) two categories.
One is to rely on the volatile decomposition of inorganic salts in the dry powder, and the combustion process of the fuel produced by the free radicals or active groups of chemical inhibition and negative catalytic effect, so that the chain reaction of combustion is interrupted and extinguish the fire;
The second is to rely on the dry powder powder falls outside the surface of the combustible material, the chemical reaction occurs, and under the action of high temperatures, the formation of a layer of glassy cover, thus insulating the oxygen, and then asphyxiation. Extinguish the fire. In addition, there are some dilution of oxygen and cooling effect.
Expanded
Dry powder fire extinguishers to put out flammable, flammable liquid fire, should be aimed at the root of the flame sweeping, if the liquid fire was put out of the liquid fire is a flow of combustion, it should be aimed at the root of the flame by the near and far, and sweeping left and right, until all the flames are extinguished.
If the combustible liquid is burning inside the container, the user should aim at the root of the flame and sway and sweep, so that the dry powder sprayed out of the stream covers the entire surface of the container opening; when the flame is driven out of the container, the user should continue to spray until the flame is completely extinguished. When fighting the fire of combustible liquid in the container, it should be noted that the nozzle should not be directly aimed at the liquid surface, to prevent the impact of the jet stream to make the combustible liquid splash and expand the fire, resulting in difficulties in extinguishing the fire.
If when combustible liquids in metal containers burning time is too long, the wall temperature of the container has been higher than the spontaneous combustion point of combustible liquids, it is very easy to cause the phenomenon of rekindling after extinguishing the fire, if used in conjunction with the foam extinguishers, it is better to extinguish the fire.
The use of ammonium phosphate dry powder fire extinguishers to fight solid combustible fires, should be aimed at the most intense burning spray, and up and down, left and right sweeping. If conditions permit, the user can carry the fire extinguisher along the burning material around the side of the spray, so that the dry powder fire extinguishing agent evenly sprayed on the surface of the burning material, until all the flames are extinguished.
Baidu Encyclopedia-Dry Powder Fire Extinguisher