What is dry powder extinguishing agent? What is the principle of dry powder extinguishing agent?

As a firefighting powder, dry powder fire extinguishing agent is made by the fire extinguishing base (such as baking soda, ammonium carbonate, ammonium phosphate, etc.) and the amount of lubricant (magnesium stearate, mica, talc, etc.) (Silica gel) and co-milled to make small particles, using carbon dioxide as jet power.Ejection of the powder, the concentration of dense, fine particles, covered in solid combustion on the combustion barrier can constitute a barrier, while the precipitation of non-flammable gases, Reduce the concentration of oxygen in the air and extinguish the flame