GBL-series Viton Extreme builds on the ETP terpolymer backbone with a peroxide-cure system, adding stronger steam and acid resistance on top of the base chemistry's amine/high-pH performance. FITCO specifies GBL where a process combines high-pH or amine exposure with steam cycling — a combination that pushes past what base ETP-S is optimized for.
| Temperature range | -20°C to +230°C |
|---|---|
| Hardness range | 70–90 Shore A |
| Relative cost | $$$$ |
| Resists | Strong bases, amines, steam, acids, plus standard FKM's hydrocarbon/fuel resistance |
| Avoid with | Same general limits as standard FKM outside its improved high-pH/steam range |
| Standards | AS568 / ISO 3601 / BS 4518 |
Viton Extreme — GBL Series isn't a single formulation — the grade below matters as much as the base compound once your application gets specific.
The standard GBL-series compound — peroxide-cured for improved steam and acid resistance over the base ETP-S chemistry.
A higher-performance GBL formulation with the strongest steam and acid resistance in the Viton Extreme range — specified for the most demanding combined high-pH/steam service.
Not sure which sub-grade fits your application? Send us your fluid, temperature and pressure and our engineers will confirm — send an enquiry →
General-purpose seal for mineral oils, fuels and hydraulic fluids.
-20°C to +200°CHigh-temperature, chemical-resistant sealing for oil & gas and process industries.
-15°C to +327°CNear-universal chemical resistance for the most demanding process seals.
FEP encapsulated O-rings use standard Silicone or standard Viton FKM as the elastomer core — not specialty sub-grades. If you need FEP encapsulation, the core is standard FKM, not this specific grade.
Standard FKM details → Specialty ProductThin PTFE coating on the FKM O-ring surface — reduced assembly friction, anti-stick, dry lubrication for production line assembly without grease.
PTFE Coated O-Rings → Custom SizesNon-standard ID or cross-section? FITCO manufactures custom O-rings in all Viton grades to any dimension — send your drawing or ID × CS in mm.
Custom O-Ring sizes →Send us your fluid, temperature and pressure — our engineers will confirm the compound.
