Silicone High-Temperature Seal Guide
Silicone High-Temperature Seal Guide
Silicone elastomers deliver unmatched temperature flexibility and cleanliness, making them ideal for food, medical, aerospace, and HVAC applications. This guide outlines formulation choices, thermal performance, and validation testing.
## Performance Summary
| Property | Typical Range | Notes |
| — | — | — |
| Continuous temperature | -60 °C to +230 °C | Short peaks to +250 °C (verify grade) |
| Hardness | 30–80 Shore A | 50–60A common for gaskets, 70–80A for dynamic seals |
| Compression set | ≤25 % @ 200 °C with peroxide cure | Post-curing improves results |
| Electrical insulation | Excellent | Volume resistivity ~10¹⁴ Ω·cm |
| Cleanliness | FDA, USP Class VI, BfR, 3-A grades available | Ideal for sanitary service |
## Grade Selection
– **Platinum-cured (LSR)** – ultra-clean, low volatile; preferred for medical and food contact.
– **Peroxide-cured** – better compression set, cost-effective for industrial use.
– **High-consistency rubber (HCR)** – extrusion/molding, higher tear strength.
– **Liquid silicone rubber (LSR)** – injection-molded components with tight tolerances.
– **FVMQ (fluorosilicone)** – improved fuel/solvent resistance with similar temperature capability.
## Design Tips
– Allow for higher thermal expansion vs. other elastomers; adjust groove fill accordingly (typically ≤90%).
– Use 30–40 % squeeze for static seals due to lower modulus; dynamic applications should drop to 15–20 %.
– Mind tear strength—avoid sharp edges and lubricate during installation.
– For steam/autoclave service, verify formulation resists hydrolysis; some silicone grades require protective coatings.
– Consider colour coding (platinum vs. peroxide) for easier identification in regulated environments.
## Testing Checklist
– Compression set (ASTM D395) at both low and high temperatures.
– Steam and sterilisation exposure (SIP/CIP) cycles.
– Outgassing (ASTM E595) for aerospace/vacuum applications.
– Extractables testing for food and pharma per FDA/USP requirements.
– Tear/elongation tests to ensure durability in dynamic environments.
## Related Resources
– [Fluorosilicone Guide](/materials/fluorosilicone-o-rings/)
– [Maintenance Checklist](/o-ring-maintenance-guide/)
– [Design Services](/services/design-services/) – groove optimisation for silicone seals.
Need to certify silicone seals for FDA or USP Class VI service? Send process conditions and regulatory requirements via the [quote form](/quote/custom/) for recommended compounds and validation plans.
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