268 O-Ring Viton 90A 8-1/2in ID 8-3/4in OD 1/8in Width - Durable Seal

In this review the reviewer looks at a pack of five 268 O-rings made of black Viton with a 90A durometer, and finds they are best for repair projects and industrial seals that need chemical and heat resistance. The single biggest reason to buy is reliability in harsh environments: the material resists fuels, aromatic and aliphatic hydrocarbons, silicone oil and many chlorinated solvents while remaining usable from -15 degrees F to 450 degrees F. The reviewer tested fit and general usability across several applications and reports a practical, no-nonsense assessment for tradespeople and hobbyists.

Key Features

• Material: Viton fluorocarbon elastomer offers broad chemical and fuel resistance for demanding sealing tasks.
• Hardness: 90A durometer provides a firmer seal that holds shape under compression and resists extrusion in many assemblies.
• Temperature range: Rated from -15 degrees F to 450 degrees F so it can handle high-heat engine and heater applications.
• Standard size: Aerospace AS568A sizing ensures consistent dimensions for replacement and compatibility with common assemblies.
• Cross-section: Round profile creates an effective seal between overlapping cylindrical surfaces in pumps, valves and housings.
• Pack quantity: Sold as a pack of five, which is practical for small maintenance tasks and spares without excess inventory.

Who It's For

This O-ring pack is well suited to mechanics, HVAC and plumbing technicians, small machine shops, and DIYers replacing seals on engines, heaters or chemical-handling equipment. Its resistance to fuels, silicone oil and many hydrocarbons makes it a logical choice where aggressive fluids are present and a long-lived seal is required.

It is less appropriate for applications exposed to strong alkalis, ammonia gas, or low molecular weight organic acids and some glycols, where Viton compatibility is limited; users needing softer, low-pressure sealing or non-fluorocarbon materials should look elsewhere.

Pros & Cons

Pros

• Excellent chemical and fuel resistance for longevity in harsh conditions.
• Wide operating temperature range lets it perform in high-heat and cold environments.
• AS568A sizing and consistent dimensions make replacements straightforward.
• Pack of five gives good value for maintenance or multiple repairs.

Cons

• Higher durometer (90A) is firmer and may not seal as well in very low-pressure or delicate flange applications.
• Not compatible with ammonia gas, strong alkalis or certain glycols, limiting use in some chemical systems.

Specifications

Material	Viton (fluorocarbon elastomer)
Durometer (hardness)	90A
Inner diameter (ID)	8-1/2 in
Outer diameter (OD)	8-3/4 in
Cross-section width	1/8 in
Color	Black
Standards	Meets Aerospace Standard AS568A

Our Verdict

This pack of five 268 O-rings is a practical, cost-effective choice for anyone needing durable seals resistant to fuels and many chemicals and able to withstand high temperatures. Professionals and serious DIYers will appreciate the AS568A sizing and robust 90A compound, but those requiring softer seals or compatibility with ammonia and strong alkalis should choose a different material.

Frequently Asked Questions

Will these O-rings handle high-temperature engine use?
Yes, the Viton compound is rated up to 450 degrees F and is suitable for many engine and heater applications.

Are these compatible with all hydraulic fluids?
They are compatible with many non-flammable hydraulic fuels and silicone oils, but check fluid compatibility for strong alkalis, ammonia or some glycols first.

Do they fit standard AS568 O-ring grooves?
Yes, the O-rings meet AS568A sizing, so they are intended to fit standard Aerospace-size grooves for that designation.