FRP pipes and valves have been widely used due to its better chemical resistance than other materials. General stainless steel valves cannot be used under the condition of high temperature hydrochloric acid and acid alkali alternation. The price of FRP valves is only about 1/3 of that of stainless steel valves of the same size.

The conductivity of industrial water and its aqueous solution is greater than 10-4 S/cm, the conductivity of acid, alkali and salt solution is 10-4~10-1 S/cm, and the conductivity of low degree distilled water is 10-5 S/cm. There is no problem with these uses. For example, if the conductivity of petroleum products and organic solvents is too low, they cannot be used. The water solution used may be proportioned with industrial water, and the conductivity will be slightly higher, which is conducive to flow measurement. The following figure lists the conductivity of several liquids at 20 ° C.