Kalrez 7075 vs Simriz SZ485: FFKM Compound Comparison
Verified by Rachel Mayfield, Supply Chain Analyst - April 2026
Kalrez 7075 and Simriz SZ485 are both perfluoroelastomer (FFKM) compounds used in chemical, refinery, and process applications. Kalrez 7075 vs Simriz SZ485 They share similar chemistry but differ on temperature ceiling, hardness, and intended service. This page compares the two side-by-side and explains when to specify each.
Side-by-side comparison
| Property | Kalrez 7075 | Simriz SZ485 |
|---|---|---|
| Manufacturer | DuPont (Chemours) | Freudenberg-NOK |
| Compound | 7075 | SZ485 |
| Maximum continuous temp | 327°C | 280°C |
| Minimum temp | 0°C | -10°C |
| Hardness | 75 Shore A | 75 Shore A |
| Colour | White-Cream | Off-White |
| Typical applications | Semiconductor wafer fabrication, plasma etch, CVD chambers | Semiconductor wet/dry etch |
When to specify Kalrez 7075
Kalrez 7075 suits semiconductor wafer fabrication and similar service. Continuous temperature window is 0°C to 327°C, hardness 75 Shore A. Manufactured by DuPont (Chemours).
When to specify Simriz SZ485
Simriz SZ485 suits semiconductor wet/dry etch and similar service. Continuous temperature window is -10°C to 280°C, hardness 75 Shore A. Manufactured by Freudenberg-NOK.
Key differences
- Temperature ceiling: Kalrez 7075 runs 47°C hotter (327°C vs 280°C). Specify the higher-rated compound when continuous service is above 280°C.
- Hardness: Both are 75 Shore A, so groove design and squeeze percentage are interchangeable.
- Manufacturer: Kalrez 7075 is from DuPont (Chemours); Simriz SZ485 is from Freudenberg-NOK. Lead time and UK availability vary by brand.
- Cost: FFKM pricing varies by manufacturer, batch size, and stock position. Both compounds are at the premium end of elastomer pricing (£30 to £500+ per O-ring depending on size).
Get a UK quote on either compound
Related pages
Frequently Asked Questions
Can I substitute Kalrez 7075 for Simriz SZ485?
Yes, Kalrez 7075 and Simriz SZ485 are both FFKM compounds with overlapping chemical compatibility. Verify your specific fluid against both manufacturers' compatibility tables before substitution. Temperature window, hardness, and certifications may differ.
Which is hotter: Kalrez 7075 or Simriz SZ485?
Kalrez 7075 has a higher continuous temperature ceiling (327°C vs 280°C, a 47°C difference).
Which costs less: Kalrez 7075 or Simriz SZ485?
FFKM compound pricing depends on manufacturer, batch size, certifications, and current stock position rather than headline brand. Both compounds are at the premium end of elastomer pricing. Get current UK quotes on both before specifying.
Where can I buy Kalrez 7075 or Simriz SZ485 in the UK?
Both compounds are supplied in the UK by independent FFKM seal specialists carrying multiple manufacturer lines. Lead time is typically 2-5 working days for stock BS 1806 / AS568 sizes, 4-8 weeks for custom-moulded sizes.