Chemraz 615 vs Kalrez 4079 FFKM Comparison

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Chemraz 615 vs Kalrez 4079 FFKM Comparison

Reviewed by MLC Editorial Team | 29 July 2026

Comparing the Chemraz and Kalrez ranges generally? See the full Chemraz vs Kalrez cross-reference covering all 6 equivalent grades. This page covers the Kalrez 4079 and Chemraz 615 pair specifically.

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Chemraz 615 and Kalrez 4079 are both perfluoroelastomer (FFKM) compounds used in chemical, refinery, and process applications. Chemraz 615 vs Kalrez 4079 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	Chemraz 615	Kalrez 4079
Manufacturer	Greene Tweed	DuPont (Chemours)
Compound	615	4079
Maximum continuous temp	324°C	316°C
Minimum temp	-10°C	0°C
Hardness	75 Shore A	75 Shore A
Colour	Black	Black
Typical applications	Refinery, chemical, hot amines, steam	Steam, hot amines, ethylene oxide, sour gas, refinery valves, pulp and paper digesters

When to specify Chemraz 615

Chemraz 615 suits refinery and similar service. Continuous temperature window is -10°C to 324°C, hardness 75 Shore A. Manufactured by Greene Tweed.

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.

Key differences

Temperature ceiling: Chemraz 615 runs 8°C hotter (324°C vs 316°C). Specify the higher-rated compound when continuous service is above 316°C.
Hardness: Both are 75 Shore A, so groove design and squeeze percentage are interchangeable.
Manufacturer: Chemraz 615 is from Greene Tweed; Kalrez 4079 is from DuPont (Chemours). 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

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Related pages

References

Greene Tweed - Chemraz 615
DuPont (Chemours) - Kalrez 4079
BS 1806
ISO 3601

Frequently Asked Questions

Can I substitute Chemraz 615 for Kalrez 4079?

Yes, Chemraz 615 and Kalrez 4079 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: Chemraz 615 or Kalrez 4079?

Chemraz 615 has a higher continuous temperature ceiling (324°C vs 316°C, a 8°C difference).

Which costs less: Chemraz 615 or Kalrez 4079?

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 Chemraz 615 or Kalrez 4079 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

Greene Tweed — Chemraz 615
DuPont (Chemours) — Kalrez 4079
BS 1806
ISO 3601

Independent UK engineering trade publication. Company profiles cross-referenced with Companies House.

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