Kalrez 4079 vs Simriz SZ487: FFKM Compound Comparison
Verified by Rachel Mayfield, Supply Chain Analyst - April 2026
Kalrez 4079 and Simriz SZ487 are both perfluoroelastomer (FFKM) compounds used in chemical, refinery, and process applications. Kalrez 4079 vs Simriz SZ487 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 4079 | Simriz SZ487 |
|---|---|---|
| Manufacturer | DuPont (Chemours) | Freudenberg-NOK |
| Compound | 4079 | SZ487 |
| Maximum continuous temp | 316°C | 300°C |
| Minimum temp | 0°C | -10°C |
| Hardness | 75 Shore A | 75 Shore A |
| Colour | Black | Black |
| Typical applications | Steam, hot amines, ethylene oxide, sour gas, refinery valves, pulp and paper digesters | Aggressive acids/bases/solvents, refinery, chemical process |
When to specify Kalrez 4079
Kalrez 4079 suits steam and similar service. Continuous temperature window is 0°C to 316°C, hardness 75 Shore A. Manufactured by DuPont (Chemours).
Limitation: Not recommended for fully fluorinated solvents; cost.
When to specify Simriz SZ487
Simriz SZ487 suits aggressive acids/bases/solvents and similar service. Continuous temperature window is -10°C to 300°C, hardness 75 Shore A. Manufactured by Freudenberg-NOK.
Key differences
- Temperature ceiling: Kalrez 4079 runs 16°C hotter (316°C vs 300°C). Specify the higher-rated compound when continuous service is above 300°C.
- Hardness: Both are 75 Shore A, so groove design and squeeze percentage are interchangeable.
- Manufacturer: Kalrez 4079 is from DuPont (Chemours); Simriz SZ487 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
- Kalrez 4079 compound details
- Simriz SZ487 compound details
- BS 1806 O-ring size chart
- ISO 3601 metric O-ring sizes
References
- DuPont (Chemours) — Kalrez 4079
- Freudenberg-NOK — Simriz SZ487
- BS 1806
- ISO 3601
Frequently Asked Questions
Can I substitute Kalrez 4079 for Simriz SZ487?
Yes, Kalrez 4079 and Simriz SZ487 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 4079 or Simriz SZ487?
Kalrez 4079 has a higher continuous temperature ceiling (316°C vs 300°C, a 16°C difference).
Which costs less: Kalrez 4079 or Simriz SZ487?
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 4079 or Simriz SZ487 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.
References
- DuPont (Chemours) — Kalrez 4079
- Freudenberg-NOK — Simriz SZ487
- BS 1806
- ISO 3601