470 O-Ring Viton 90A, 21 in ID 21-1/2 in OD - High Temperature Seal

In this review the 470 O-Ring made of black Viton is evaluated for mechanical and fluid sealing tasks where chemical and heat resistance matter most. The bottom line: this O-ring is best for technicians and hobbyists who need a compact, high-hardness seal that stands up to fuels, aromatic and aliphatic hydrocarbons, and elevated temperatures. Its biggest advantage is the material choice - Viton fluorocarbon - which brings broad chemical compatibility and a wide operating temperature range, making it a practical replacement or spare for pumps, heaters, and equipment exposed to harsh fluids.

Key Features

• Material: Made of Viton fluorocarbon elastomer, it offers superior resistance to heat, fuels and many chemicals compared with general-purpose rubbers.
• Hardness: The 90A durometer delivers a firm, durable seal suited to static and some dynamic applications where abrasion and extrusion resistance are important.
• Temperature range: Rated from -15 degrees F to 450 degrees F, it works across cold starts and prolonged high-heat environments without rapid degradation.
• Cross-section: Its round cross-section forms a reliable seal between overlapping cylindrical surfaces, which is useful for shafts, housings and closures.
• Standard sizing: Manufactured to the Aerospace Standard AS568A sizing, it fits common O-ring grooves and replacements for many industrial parts.
• Chemical compatibility: Compatible with fuels, silicone oil, chlorinated and aromatic hydrocarbons, and many hydraulic fluids for versatile use.

Who It's For

This O-ring suits mechanics, HVAC and plumbing technicians, and DIYers who repair pumps, spa heaters, classic car components and equipment exposed to fuels or solvents. The combination of high durometer and Viton chemistry makes it a good choice where a stiff, resilient seal is needed that will not swell in contact with oils and many fuels.

It is less suitable for applications requiring soft, highly elastic seals or continuous dynamic sealing with aggressive alkalies, ammonia, or low molecular organic acids, where Viton is vulnerable. Users needing very soft elastomers or compatibility with strong amines should look elsewhere.

Pros & Cons

Pros

• Excellent chemical and fuel resistance for long service life in contaminated environments.
• Wide temperature tolerance supports both cold and high-heat operations without rapid failure.
• Firm 90A hardness provides durable performance and good resistance to extrusion in many assemblies.
• AS568A sizing makes it easy to replace common O-rings in industrial equipment.

Cons

• Higher durometer can be stiff for some static seals requiring very low compression force, and a few users reported occasional leaks when fit or groove design was marginal.

Specifications

Brand	Mr O-Ring
Material	Viton (fluorocarbon elastomer)
Durometer	90A
Inner diameter	21 in
Outer diameter	21-1/2 in
Cross-section width	1/4 in
Temperature range	-15 degrees F to 450 degrees F

Our Verdict

The 470 Viton 90A O-ring is a dependable, value-minded choice for technicians and hobbyists needing a tough seal that resists fuels, many solvents, and high temperatures. Its firm hardness and AS568A sizing make it ideal for replacements in pumps, heaters and automotive systems, though those needing softer or alkali-resistant elastomers should consider alternatives.

Frequently Asked Questions

Is this O-ring compatible with gasoline and diesel?
Yes, Viton is compatible with many fuels and aromatic and aliphatic hydrocarbons, making it suitable for fuel-related seals.

Will the 90A hardness work for spa heater seals?
Yes, the firm 90A durometer is commonly used in spa heater repairs and provides durability, though correct groove fitting is essential to avoid leaks.

Can it be used in very low temperature environments?
It can operate down to about -15 degrees F, but below that temperature the material will become less flexible and may not seal as well.