There are two main methods for marking O-ring specifications. The old national standard specified it as outer diameter D × wire diameter d2, for example, O-ring 20*2.4. The new national standard (adopting ISO standards) and international standards specify it as inner diameter × cross-sectional diameter, for example, O-ring 7.5×1.8-G-N.
The currently effective national standard is GB/T3452.1-2005 "O-rings for Hydraulic and Pneumatic Use - Dimensional Series and Tolerances," which replaces older standards such as GB 3452.1-1992. The groove size standard is GB/T 3452.3-2005.
The technical requirements for O-rings include appearance requirements, dimensional requirements, and material physical property requirements. Appearance requirements conform to GB/T3452.2-2007, dimensional requirements conform to GB/T3452.1-2005, and material requirements conform to HG/T2579-2008.
