FKM (Viton) Temperature Range & Limits

FKM (Viton®) is the go-to fluoroelastomer for chemical and heat resistance, but its temperature window is not a single number—it depends on grade, cure system, and whether the limit is continuous or intermittent. This guide explains the real FKM temperature range and what degrades it, with links to our FKM/Viton O-rings and FKM vs Viton vs FPM pages.

The Temperature Window

Intermittent excursions above the continuous limit are possible for short periods; sustained over-temperature accelerates compression set and hardening.

What Limits FKM at High Temperature

• Compression set – the seal loses recovery and starts leaking.
• Post-cure – proper peroxide post-cure improves heat and compression-set performance.
• Media – amines, steam, and strong bases attack even FKM above ~150°C; FFKM or EPDM may be better.

What Limits FKM at Low Temperature

Standard FKM stiffens below about -15°C to -20°C (its TR-10 is around -10°C to -15°C). For arctic or cold-start duty, specify a low-temperature FKM or move to silicone/FKM blends.

FKM vs Alternatives by Temperature

Compare in our EPDM vs NBR vs FKM and FFKM/FKM/Aflas guides.

How to Specify FKM for Temperature

1. Define continuous vs peak temperature and duration.
2. Pick standard, high-fluorine, low-temp, or peroxide-cured grade.
3. Confirm media compatibility at temperature (not just at room temp).
4. Require proper post-cure for high-heat static seals.
5. Consider FFKM only if FKM’s chemical/heat limit is exceeded.

For aerospace high-temp duty, see our aerospace AMS 7276 FKM article.

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