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B dry powder dry powder fire extinguishing agent (MF) is mainly composed of sodium bicarbonate and a small amount of moisture-proof agents such as magnesium stearate and talcum powder. Driven by dry carbon dioxide or nitrogen, thousands of powders are sprayed from the container to form powder mist and sprayed into the combustion zone, and the sodium bicarbonate in the dry powder is decomposed at high temperature. The chemical reaction equation is as follows:

2 nah co 3→na2co 3· 1h2o· 1c 02

The reaction is endothermic and will release a lot of carbon dioxide and water. Water becomes steam after heating, which absorbs a lot of heat energy and plays a certain role in cooling and diluting combustible gas.

There are many kinds of dry powder extinguishing agents, which can be roughly divided into three categories:

Dry powder based on sodium (potassium) bicarbonate is used to extinguish fires of flammable liquids, gases and charged equipment;

Dry powder based on triammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and their mixture is used to extinguish the fire of combustible solid, combustible liquid, combustible gas and charged equipment;

Thousands of powders based on sodium chloride, potassium chloride, barium chloride and sodium carbonate are used to put out light metal fires.

Some combustible gases, such as acetylene and hydrogen, which are easily diffused, are difficult to dilute the whole range of gases after dry powder injection, and the fire extinguishing effect is not good. It is also not suitable for the fire extinguishing of precision machinery and instruments, because there are residues after the fire extinguishing.

In addition, when using dry powder to extinguish fire, attention should be paid to cooling in time to avoid re-ignition.