①Water can be chemically reactive substances on fire, can not use water to extinguish.
Can not put out fires where combustible powder (flour, aluminum powder, coal powder, sugar powder, zinc powder, etc.) is gathered; also can not put out fires in high-temperature equipment.
③ Non-water-soluble combustible liquid fires, in principle, can not be put out with water, but crude oil, heavy oil can be put out with fog water; high-pressure fog water can put out a small range of light oil fires.
④ Valuable equipment, precision instruments, books, archives fires can not be put out with water, easy to cause water damage loss, damage to equipment.
⑤ store a large number of concentrated sulfuric acid, concentrated nitric acid, and hydrochloric acid fires in the premises, you can not use straight water to put out, so as not to cause an acid splash. If necessary, fog water can be used to extinguish.