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Certifications of Elastomer O-Rings for Mass Flow Controllers Explained

Certifications of Elastomer O-RingsMass Flow Controllers (MFCs) are used in many applications that require different certification requirements for materials that could come into contact with anything going into the end product.  For gas control in bioreactors, gas is being controlled by MFCs in a gas box, in open frame systems, or mounted on a skid.  Process gasses go through the MFC and into the bioreactor to control the cell growth and cannot be contaminated by the materials in the gas supply components. Many MFCs use elastomer sealing materials and it is important to make sure you have materials that are certified to be safe for the application.  For example, our SLA Series MFCs offer USP Class VI O-rings in two different materials (Viton and EPDM – See blog on elastomer selection).  So what does this even mean?

USP Class VI

USP stands for U.S. Pharmacopeia, a private (non-government) organization that ‘promotes the public health by establishing state-of-the-art standards to ensure the quality of medicines and other health care technologies'.  For plastics, they have 6 different classes based on duration and application.  Class VI is the most stringent and requires three tests:
  • Systemic injection test
  • Intracutaneous test and
  • Implantation tests
In order to pass the Class VI standards, the product/material must exhibit a very low level of toxicity by passing all the tests requirements when tested according to ISO 10993. The FDA requires testing of finished devices, however, the demonstration of biocompatibility of materials according to USP Class VI standards is provided as an aid to device manufacturers in their material selection process.

ADI-Free / BSE-Free / TSE-Free

Another up and coming requirement is ADI free (BSE / TSE free).  This is to certify that the raw materials used in production of the elastomer contain no Animal Derived Ingredients (ADI) and are therefore Bovine Spongiform Encephalopathy (BSE) Free and Transmissible Spongiform Encephalopathy (TSE) Free with respect to source, manufacture and treatment.  This assures the user that there is no path for these pathogens to contact their process or product.  This is a statement from manufacturers certifying that there no substance of animal origin used to manufacture the product. When you see ‘CFR 21 FDA 177.2600' on MFC O-rings it means that it is on the FDA list of base elastomers that are recognized as inherently safe and classified as GRAS (Generally Recognized as Safe).

Of course, we here at Brooks Instrument are always happy to answer questions around our compliance with these standards in our products so feel free to contact us.

About The Author

Shelly McWilliams
Global Product Manager

Shelly is the global product manager for thermal mass flow controllers at Brooks Instrument.

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