#1 What are O-ring dimension standards?
The dimension of an O-ring is defined by its inner diameter and its cord thickness. In principle, it is possible to produce almost any O-ring size.
However, as this is not an efficient solution on a national and especially global level, dimensional standards for O-rings have been introduced to the market.
Important to know: A basic distinction is made between inch and metric dimensions.
Inch dimensions have their origins in the imperial system of measurement, which originated in England. However, since the rest of the world finds it difficult to calculate in “inches”, there is a conversion from the unit “inch” to the metric unit “mm” in every list of standards.
Example: 0.801 x 0.07 inch = 20.35 x 1.78 mm
Metric dimensions, on the other hand, are always given in the metric unit “mm”.
#2 What O-ring dimension standards are there?
ISO 3601 – International standard – Imperial and metric dimensions
DIN 3771 – German standard – superseded by ISO 3601 since 2010
AS 568 – American Standard – Inch dimensions
BS 1806 – British Standard – Inch dimensions
BS 4518 – British Standard – Metric dimensions
SMS 1586 – Swedish standard – Metric dimensions
NF T 47-501 – French standard – Metric dimensions
JIS B 2401 – Japanese standard – Metric dimensions