Silica is an indispensable additive for the preparation of dry powder fire extinguishing agents at home and abroad, the purpose is to prevent the dry powder fire extinguishing agent from caking during the validity period of use.

At present, in the domestic technical standards related to silica, there are no technical indicators suitable for the preparation of dry powder fire extinguishing agents. Domestic manufacturers of dry powder fire extinguishing agents are choosing them in exploration. The production areas of silica that have been selected are all over the country. Some silica can successfully prepare dry powder fire extinguishing agents with qualified water repellency; some can barely be applied; some cannot prepare dry powder fire extinguishing agents with qualified water repellency. The reason is the lack of clear technical requirements for silica. Summarizing the domestic production practice for many years, the selection method of silica is proposed as follows:

(1) The silica produced by the same process, that is, the silica produced by the precipitation method, is commonly used in domestic dry powder fire extinguishing agent production plants. From the appearance point of view, they are just different in bulk density.

(2) As an additive, each silica is prepared into an ammonium phosphate dry powder fire extinguishing agent under the same formula and production process conditions, and then their water repellency is tested and their applicability is observed. This condition is very important. Different formulas and production processes sometimes change the applicability of silica. For example, increasing the amount of silica or the amount of silicone oil will change the applicability of silica, so that there is no comparison between silica.