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When choosing an O-ring, it is not only about the right size or the right material. In many applications, a seal must also comply with specific O-ring standards, certifications, approvals or test methods. Think of drinking water installations, gas pipelines, industrial processes, food contact, pharmaceutical applications or technical sizing.
An EPDM, FKM, NBR or silicone O-ring is therefore not automatically suitable for every application. The specific compound, the operating conditions and the available documentation determine whether an O-ring actually complies. This page helps you determine which O-ring standards are relevant for your application and which cluster page is best to click through to.
The right standard depends on where the O-ring is used. In practice, O-ring standards prevent you from choosing based only on the material name. A seal in a drinking water installation requires different documentation than an O-ring in a gas application, food-grade machine or hydraulic system. That is why we have divided the most important O-ring standards into four practical categories: drinking water, gas & industry, food & pharma and sizing & testing.
For O-rings in drinking water, sanitary systems, hot water installations and fittings, drinking water standards and approvals are important. This is not only about the base material, but also about migration, odour, taste, microbiological growth and suitability under temperature load.
Examples of relevant standards and approvals include DVGW, KTW-BWGL, W270, WRAS, ACS and NSF/ANSI 61. These O-ring standards help determine whether a specific compound is suitable for contact with drinking water. Pay particular attention to the difference between “EPDM” as a material name and a demonstrably approved EPDM compound.
Gas and industrial applications involve different risks. Think of gas permeability, ageing, pressure fluctuations, explosive decompression, sour service, oil and gas, hydrogen or high pressure. Here, an O-ring must not only be chemically resistant, but also remain mechanically stable under demanding conditions.
Within this area, O-ring standards such as EN 549, EN 682, NORSOK M-710 and NACE TM0187 are relevant. AED and RGD testing can also be important in applications with rapid pressure changes. Material selection plays a major role here, for example HNBR, FKM, AFLAS, FFKM or special compounds for gas applications.
In food processing, pharmaceuticals and hygienic processes, “food grade” is often too general. It is important to know which regulation, declaration or test applies. Is it about food contact, pharmaceutical biocompatibility, migration requirements or hygienic design?
Common references include FDA, EC 1935/2004, USP Class VI, 3-A Sanitary Standards and BfR. These O-ring standards and declarations help determine whether a compound is suitable for contact with food, process media or pharmaceutical products. Depending on the application, silicone, EPDM, FKM or FFKM may be suitable, but only when the correct documentation is available.
Not every standard is about approval or safety. Some O-ring standards help with the technical specification, measurement or assessment of a seal. Think of dimensions, tolerances, groove sizes, hardness, compression set and material testing.
Important topics within this cluster include ISO 3601, AS568, DIN 3771, Shore hardness, compression set and test methods such as ASTM D2240 or ISO 815. This information is important for engineering, quality control and preventing leakage caused by incorrect fit, incorrect hardness or insufficient elastic recovery.
These terms are often used interchangeably, but they do not mean the same thing. A standard describes requirements, specifications or test methods. An approval indicates that a product or material has been assessed according to certain requirements. A certificate is the document used to demonstrate conformity. A test method describes how a property is measured or assessed.
For O-rings, this distinction is important. A material name says little without context. An EPDM O-ring may be suitable for drinking water, but that does not apply to every EPDM compound. The same applies to FKM, NBR, HNBR, silicone and FFKM. Therefore, use O-ring standards as a starting point, but always check the underlying documentation. Always look at the combination of material, compound, application and certificate.
First check what the O-ring is used for, which medium it comes into contact with and under which temperature, pressure and movement it must function. Then check which O-ring standards or certifications are relevant. Also pay attention to the compound, the available certificates, the sizing and any requirements around hardness, compression set or ageing.
Not sure which documentation is needed? Do not use O-ring standards as a separate checkbox, but as a selection aid. Ask for technical advice before ordering. This prevents an O-ring from appearing suitable on paper, while in practice it does not meet the requirements of the application.
No. EPDM is often used in drinking water applications, but only the specific compound and the correct certification determine whether the O-ring is suitable. That is why O-ring standards and certificates are important for drinking water contact.
A standard describes requirements or test methods. A certificate is the document that proves that a material, compound or product meets certain requirements.
Common references include FDA, EC 1935/2004, USP Class VI, 3-A Sanitary Standards and BfR. Which one is needed depends on the application and market.
For gas and industry, EN 549, EN 682, NORSOK M-710, NACE TM0187 and AED/RGD testing are among the relevant references.
