This standard specifies the method for determining the pH value of aqueous suspensions of rubber compounding agent settling hydrated silica. It is suitable for settling hydrated silica. The user needs to have practical experience in formal laboratory work and be careful that not all possible safety issues are covered. Reference documents include GB/T 6682, GB/T 8170, GB/T 9724, HG/T 3061. Reagents include distillation water, ethanol and standard buffer solutions. The required instruments are conicalflask, pH Meter, analytical balance and industrial Balance. Sampling needs to be carried out in accordance with HG/T 3061 regulations. The sample needs to reach room temperature before the test, and the test conditions are not contaminated by chemical gases such as acid and alkali.