439 Viton O-Ring 90A 6-1/2in ID 7in OD Pack of 5 - High Temp Seal

In this review the 439 Viton O-Ring 90A (pack of 5) is evaluated for mechanics, fabricators, and maintenance technicians who need a reliable high-temperature seal. The bottom line: this set is for anyone who requires a small stock of consistent, durable Viton o-rings that resist fuels, oils and elevated temperatures. The reviewer found the 90A durometer provides a firm sealing surface while the actual dimensions closely match nominal size, making these o-rings a practical choice for routine replacement or inventory without overpaying for specialty elastomers.

Key Features

• Material: Made from Viton (FKM) so the o-ring resists fuels, mineral oils, hydraulic fluids and many solvents for longer service life.
• Durometer: The 90A hardness offers a firm sealing surface that performs well under compression in static and low-movement dynamic seals.
• Temperature range: Rated from -26C (-15F) to 232C (450F) so the rings can be used in very high temperature applications without rapid degradation.
• Size accuracy: Actual dimensions (6.475in ID, 7.025in OD, 0.275in CS) closely track the nominal size for predictable fit in standardized grooves.
• Versatility: Performs in contact with petroleum products, fuels including methanol or ethanol blends, diesel, silicone oils, ozone and weather exposure for a wide range of sealing tasks.
• Pack quantity: Sold as a pack of 5 to keep spare parts on hand for scheduled maintenance or small repair jobs.

Who It's For

These Viton o-rings suit industrial maintenance crews, marine technicians, and automotive professionals who need seals resistant to fuels, high heat and chemical exposure. The firm 90A durometer works well for static seals and applications where a durable, less-compressible ring is preferred.

Those needing extremely soft or low-friction seals, or applications requiring food-grade elastomers, should look elsewhere; this product is optimized for chemical and temperature resistance rather than very low hardness or regulatory food-contact approvals.

Pros & Cons

Pros

• High chemical and temperature resistance makes these rings durable in harsh environments.
• Accurate actual dimensions provide reliable fit for AS568-equivalent size standards.
• 90A durometer balances resilience and sealing force for many static seal uses.
• Pack of 5 gives immediate spares for maintenance without bulk storage of many sizes.

Cons

• 90A hardness may be too stiff for seals that require very soft or highly conformable material.
• Not specified for food-contact or pharmaceutical approvals, so unsuitable for those regulated uses.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal Dimensions	6-1/2in ID, 7in OD, 1/4in CS
Actual Dimensions	6.475in ID, 7.025in OD, 0.275in CS
Metric Dimensions	164.47 mm ID, 178.45 mm OD, 6.99 mm CS
Temperature Range	-26C (-15F) to 232C (450F)
Pack Quantity	5 rings

Our Verdict

The 439 Viton O-Ring 90A in a pack of 5 is a practical, good-value option for professionals needing heat- and chemical-resistant seals that match AS568 size expectations. Buy it if you need dependable, long-lasting rings for fuel, oil or high-temperature applications; choose a different compound or lower durometer if your job requires food-contact compliance or very soft seals.

Frequently Asked Questions

Are these o-rings suitable for fuel exposure?
Yes. The Viton (FKM) compound resists petroleum products, fuel blends with methanol or ethanol, and diesel including biodiesel blends.

Do the rings meet a standard size?
They are offered to match AS568-equivalent sizing with listed actual and nominal dimensions for predictable fit.

What temperatures can these o-rings handle?
The rated range is -26C (-15F) up to 232C (450F), suitable for many high-temperature sealing tasks.