Verified by Rachel Mayfield, Supply Chain Analyst - April 2026
Simriz SZ481 is a 75 Shore A perfluoroelastomer (FFKM) manufactured by Freudenberg-NOK. It seals continuously to 230°C and is specified for general chemical process and similar service. Chemical-grade FFKM, marketed as Kalrez 6375 equivalent for sub-230C.
Specifications
| Property | Value |
|---|
| Compound | SZ481 |
| Manufacturer | Freudenberg-NOK |
| Maximum continuous temperature | 230°C |
| Minimum temperature | -10°C |
| Hardness | 75 Shore A |
| Colour | Black |
| Material family | Chemical-grade FFKM, marketed as Kalrez 6375 equivalent for sub-230C |
Where Simriz SZ481 is used
Simriz SZ481 is specified for: General chemical process, pharma.
Simriz SZ481 equivalents from other FFKM manufacturers
If Simriz SZ481 isn't available, these compounds from competing manufacturers have similar chemistry and operating windows. Always verify against your actual fluid and temperature before substitution.
| Equivalent compound | Manufacturer | Max temp | Hardness | Direct match |
|---|
| Kalrez 6375 | DuPont (Chemours) | 275°C | 75 Shore A | approx |
| Chemraz 555 | Greene Tweed | 240°C | 75 Shore A | ✓ |
Available O-ring sizes
Simriz SZ481 is supplied in:
- BS 1806 sizes: BS001 to BS932 (UK / EU standard, imperial-origin metric)
- AS568 sizes: -001 to -932 (US standard, dimensionally identical to BS 1806)
- ISO 3601 sizes: metric IDs from 2 mm to 670 mm with cross-sections 1.0 mm to 7.0 mm
- JIS B 2401: P, G, S series (Japanese OEM equipment)
- Custom / non-standard: built-to-print for OEM applications
For a list of sizes commonly stocked in the UK, see the BS 1806 size chart, ISO 3601 metric chart, or contact a UK seal specialist below.
UK availability
Simriz SZ481 is supplied in the UK by FFKM specialists carrying multiple manufacturer lines. Lead time is typically 2-5 working days for stock sizes, 4-8 weeks for custom-moulded sizes. Use the form below to get a quote from a UK FFKM specialist.