C, the PH value of the aqueous solution ⑻, specific resistance ⑼. An important index to characterize the impurity content and quality stability of silica gel desiccant. The PH value of ordinary silica gel is between 4 and 8, and it is economical to control it at about 5; The indicator indicating silica gel needs to be stable in a strong acidic environment, so the PH value will be relatively low, around 2.5. The specific resistance of silica gel is generally in the range of thousands to tens of thousands of ω. cm。

D, specifications and particle size pass rate. Silica gel with different specifications (particle size range ⑾, shape) is used for different packaging needs (different packaging sizes, different packaging materials, different moisture absorption speed requirements, etc.); The number of particles that meet the specification requirements in raw materials is called particle size qualification rate (expressed as mass percentage).

E, bulk density. Represents the volume occupied by a certain amount of desiccant, in g/m3. Also known as bulk density and packing density. Bulk density plays an important role in the formulation of desiccant packaging specifications and the calculation of fixed volume desiccant dosage. The bulk density of type a silica gel is about 740 ~ 800 g/l.