JJG (Light Industry) 51-2000 "Paper Porosity Tester verification code" specifies the method of verification and technical requirements of paper Porosity Tester. The code refers to ISO 5636-1:1984 and ISO 5636-2:1984 standards, and is mainly applicable to Schopper type Porosity Tester. Measurement range is 1 × 10 ^ -2 μm/(Pa · s) to 1 × 10 ^ 2 μm (Pa · s). The code covers the verification range of breathalyzer, Measurement performance requirements and general technical requirements, including Appearance inspection, sealing, clamp ring coaxiality, etc. In addition, the verification environmental conditions, verification tools and methods are stipulated, and the qualified and unqualified results are handled. The verification period is generally one year.