What is ISO 3601
The original product and technical standard of O-ring is DIN 3771. The ISO 3601 series standard in 2010 replaced the DIN 3771 series standard, becoming the latest executive standard of O-ring. Subsequently, Global O-rings and seals define the quality acceptance criteria for all O-rings to meet ISO 3601-3 Class N, which classifies surface defects and specifies the maximum acceptable limits for these defects.
ISO 3601-1: Dimensional tolerances
ISO 3601-1 specifies two types of O-rings: Class A and Class B. The tolerance of Class A O-ring is equivalent to that used in AS568, and more tight than that of Class B O-ring. It is applicable to industrial or aerospace applications, when the application or housing requires stricter tolerance. Class B O-rings have a slightly wider tolerance and are suitable for general applications.
ISO 3601-3: Quality acceptance criteria
ISO 3601-3 was originally developed for universal O-rings, but the standard has been revised and improved over the years, including three levels of defects (N, S, CS) according to the application.
Class N: acceptance standard of universal O-ring.
Class S: Quality requirements for best performance industrial and aerospace applications.
Class CS: Special and critical sealing applications, such as certain aerospace applications and critical oxygen service applications.
Examples of surface defects characterized by this standard include flash, offset, parting line protrusion, back skin, over trim, flow marks, unfilled, and indentation.
ISO 3601 Metric O-ring Dimension Table
The ISO 3601 standard issued by the International Organization for Standardization contains two groups of O-rings, Grade A and Grade B. Class A corresponds to the current format of American standard AS 568B (900 series pipe fittings O-ring is not included). The ISO 3601-1 size code of these O-rings is the same as the dash number of AS 568. Level B allows the production of technically acceptable and economical "metric" size O-rings that can then be installed in metric grooves. The first digit of the size code represents the cross section group (AE), while the last four digits represent the inside diameter of the O-ring rounded to one tenth of a millimeter. The original product and technical standard of O-ring is DIN 3771. The 2010 ISO 3601 series standard replaces the DIN 3771 series standard and becomes the latest executive standard of O-ring