FDA silicone O-rings: when you need them and how to choose
In food and beverage machinery a seal must not only seal but also be suitable for contact with the product. Here is what to know about FDA silicone O-rings.
In the food and beverage sector and in many hygienic applications, choosing a seal is not only about sealing. The material comes into contact with the product, so it must be suitable for food contact, as well as withstand washing, sanitising temperatures and detergents. One of the most used materials in these cases is silicone in an FDA-compliant grade.
What "FDA" means
The term indicates that the compound is formulated with ingredients permitted by the US Food and Drug Administration rules for materials intended to come into contact with food. It is a widely used reference in Europe too, where European regulations on food contact materials also apply. If your application requires a specific certificate or declaration of compliance, always check the documentation available for the product before buying, or contact us.
Why silicone
- Wide temperature range: silicone stays elastic both at low and high temperatures, much more than NBR and EPDM. This makes it suitable for cold rooms, ovens, pasteurisers and sterilisation cycles.
- Inertness: it does not release odours or flavours and resists ageing and ozone well.
- Colour options: besides the classic red or transparent, coloured versions help identify food-grade seals at a glance.
The limits to know
- Low mechanical strength: silicone tears and wears more easily than other elastomers. It is therefore ideal for static seals (lids, flanges, fittings) or very limited movement, not for dynamic seals under heavy friction.
- Compatibility with oils and steam: it is not suitable for mineral oils and fuels; for high-pressure steam, specific compounds or other materials should be evaluated.
- Gas permeability: higher than other elastomers; keep this in mind in applications with pressurised gases.
Alternatives for food contact
Besides silicone, food-contact grades exist for other materials, for example EPDM (excellent with hot water, steam and detergents), FKM (for fats, oils and high temperatures) and PTFE (chemically inert, for low-friction dynamic seals). The choice depends on the product handled: an O-ring working with milk and hot water has different needs from one in contact with vegetable oils or acidic juices.
What you will find in our catalogue
In the O-ring category you will find silicone families, including FDA-compliant versions, in various sizes and colours, as well as O-rings in EPDM, FKM and other materials. Each item shows material, cross-section and temperature indications. Silicone cord is also available for making seals of non-standard diameters.
Maintenance tips for food lines
- Plan replacements: on food lines it pays to replace seals at regular intervals rather than waiting for a leak, to avoid contamination.
- Inspect after washing: swelling, cracks or loss of elasticity indicate incompatibility with detergents or temperatures.
- Use food-grade lubricants during assembly.
- Keep food-grade seals stored separately from industrial ones to avoid mix-ups.
If you need a seal for a food application and are not sure about the material, write to us with the product handled, the temperatures and the detergents used: we will help you choose.
Frequently asked questions
Are silicone O-rings suitable for steam?
It depends on temperature, pressure and cycle frequency. For steam, EPDM or specific compounds are often preferred: tell us the conditions and we will help you choose.
Is red silicone always food grade?
No, colour alone does not guarantee suitability for food contact. Always refer to the product description and the available documentation.
How often should they be replaced on food lines?
It depends on washing, temperatures and products handled. Many companies set a fixed interval in their maintenance plan so as not to wait for signs of wear.
