438 Viton O-Ring 90A 6-1/4 in ID Pack of 10 - Durable High Temp Seal

In this review the focus is on the 438 Viton O-Ring in a pack of 10, a straightforward choice for technicians and hobbyists who need a robust, high-temperature sealing solution. The bottom line: this kit delivers reliable chemical and heat resistance in a commonly used AS568 size, making it a practical buy for applications exposed to fuels, oils, or elevated temperatures. The reviewer found the 90A durometer Viton compound to balance firmness and sealing conformity while the pack quantity covers maintenance and small projects.

Key Features

• Material: Fluorocarbon Viton (FKM) offers excellent resistance to high temperature, ozone and many organic solvents which makes these o-rings suitable for demanding environments.
• Durometer: The 90A hardness provides a firm cross-section that maintains a reliable seal under pressure while resisting extrusion in harsh service conditions.
• Size accuracy: Nominal and actual dimensions are provided so installers can match existing hardware precisely and avoid fitment guesswork.
• Temperature range: Rated from -26C to 232C (-15F to 450F), enabling use in high-temp air, engine compartments, and other elevated-temperature systems.
• Chemical compatibility: Performs well with petroleum fuels, methanol or ethanol blends, diesel and biodiesel, mineral oils, silicone fluids and many strong acids for broad industrial use.
• Pack size: Sold as a pack of 10 which keeps spare parts on hand for routine maintenance and small repair jobs without buying bulk quantities.

Who It's For

These o-rings suit professional mechanics, HVAC technicians, and industrial maintenance personnel who need an AS568 438 sized seal that withstands fuels, oils and elevated temperatures. Their compatibility with common automotive and hydraulic fluids makes them practical for field repairs and scheduled maintenance.

Users who need a softer, lower durometer seal for delicate low-pressure systems or who require non-fluorocarbon materials for specific chemical incompatibilities should look elsewhere. This product is targeted at applications where high temperature and chemical resistance matter more than a soft feel.

Pros & Cons

Pros

• Excellent chemical and heat resistance from the Viton (FKM) compound for long-lasting seals in harsh environments.
• 90A durometer delivers a firm, resilient seal that resists deformation under load and high temperature.
• Clear nominal and actual dimensions reduce sizing errors and speed installation.
• Pack of 10 gives good value for maintenance or multiple repair tasks without excess waste.

Cons

• Higher durometer means a firmer feel that may not be ideal for very low-pressure or ultra-sensitive sealing surfaces.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal Dimensions	6-1/4 in ID, 6-3/4 in OD, 1/4 in CS
Actual Dimensions	6.225 in ID, 6.775 in OD, 0.275 in CS
Metric Dimensions	158.12 mm ID, 172.10 mm OD, 6.99 mm CS
Temperature Range	-26C (-15F) to 232C (450F)
Pack Quantity	10 o-rings

Our Verdict

For anyone needing a dependable AS568 438 sized seal that copes with heat and aggressive fluids, this 90A Viton pack is a sensible, cost-effective choice. It offers precise sizing, robust chemical tolerance and a temperature range that suits automotive and industrial service, making it good value for maintenance crews and engineers who prioritize durability.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel?
Yes, the Viton compound performs well with diesel and biodiesel blends according to the product specifications.

Will the 90A hardness seal well in hydraulic applications?
Yes, the 90A durometer is firm and resists extrusion, making it suitable for many hydraulic and pneumatic sealing points, though softer seals may be preferred for very low-pressure systems.

Do these meet AS568 size standards?
Yes, the o-rings are described as meeting the AS568 size standards and include both nominal and actual dimensions for confirmation.