USP Class VI O-Rings (Medical)

For O-Rings that contact medicine, patients, or the human body, a compound choice is not enough. You have to prove the material is biologically safe. USP Class VI is the benchmark most medical and pharmaceutical work relies on.

What USP Class VI is

USP Class VI is the most stringent of the six biological reactivity classifications defined in the United States Pharmacopeia (USP) for plastics and elastomers. Passing indicates that a material has low biological reactivity, which is why it is so often called out for seals in medical and pharmaceutical equipment. Note that Class VI certifies the material itself, not the finished device.

The tests it requires

Class VI qualification is based on three in-vivo (animal) tests:

• A systemic (acute) toxicity test, checking for reactions to substances that leach from the material.
• An intracutaneous reactivity test, checking for local tissue irritation.
• An implantation test, checking the response to material placed in living tissue.

A compound must pass all three to carry the Class VI designation.

O-Ring compounds that meet it

Medical-grade silicone is the most common USP Class VI O-Ring material, valued for its cleanliness and wide temperature range. Other elastomers are also available in Class VI grades, and Class VI is frequently specified alongside FDA compliance for a fuller regulatory picture.

How The O-Ring Store supports it

We supply O-Rings in USP Class VI compounds for medical and pharmaceutical applications, and can confirm the grade and available documentation before you order.

Need a USP Class VI O-Ring for a medical or pharmaceutical build? Contact us with your size and application and we will confirm the compound and paperwork.