363 Viton O-Ring 75A Durometer 6-1/2in ID - Durable Chemical Seal

In this review the 363 Viton O-ring is evaluated as a straightforward replacement seal for applications that demand chemical and heat resistance. The bottom line: it is best suited for technicians, hobbyists, and maintenance personnel who need a reliably sized O-ring that resists fuels and many solvents while enduring high temperatures. The reviewer found the pack of ten offers clear value for routine replacement and retrofit tasks where a 6-1/2in ID, 3/16in width seal with a 75A hardness is required.

Key Features

• Material: Viton construction provides strong resistance to heat, fuels and many chemicals, extending service life in demanding environments.
• Temperature range: Rated from -15 degrees F to 400 degrees F, it can handle applications from cold storage to high-heat assemblies without rapid degradation.
• Durometer: The 75A hardness balances resilience and compression set resistance so the ring holds a seal under moderate static and dynamic loads.
• Cross-section: Round profile gives a consistent sealing surface between overlapping cylindrical parts for predictable leak control.
• Compatibility: Suitable for non-flammable hydraulic fuels, silicone oils, aromatic and aliphatic hydrocarbons and many chlorinated solvents commonly encountered in service work.
• Value pack: Sold as a pack of 10, making it convenient and economical for repeat maintenance and multiple installations.

Who It's For

The 363 Viton O-ring is intended for mechanics, field technicians and home shop users replacing seals on fuel systems, fittings and cylindrical assemblies that encounter heat, fuel or aggressive solvents. Its size and 75A durometer make it particularly useful where a firmer seal is preferred over very soft compounds.

It is not the best choice for systems exposed to low molecular organic acids, ammonia gas, strong alkalis or glycol-based brake fluids, and it should be avoided where prolonged contact with super-heated steam is expected; users with those specific chemical exposures should select a different elastomer.

Pros & Cons

Pros

• Excellent heat and fuel resistance suitable for high-temperature and hydrocarbon-exposed seals.
• Consistent fit and sizing that customers report work well for MSA fuel bottles and other replacement uses.
• Good durability and leak resistance in typical service applications, making the pack cost-effective.

Cons

• Viton is vulnerable to certain chemicals such as low molecular organic acids, ammonia and some alkalis, limiting its universality.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner Diameter (ID)	6-1/2in
Outer Diameter (OD)	6-7/8in
Cross-section / Width	3/16in
Durometer	75A
Temperature Range	-15 degrees F to 400 degrees F

Our Verdict

The 363 Viton O-ring is a practical, cost-effective choice for anyone needing a reliable replacement seal for fuel, hydraulic and heat-exposed applications. Its 75A hardness and Viton compound make it durable in many service environments, and the pack of ten reduces downtime for routine maintenance. Choose a different material only if your system sees acids, strong alkalis or glycol-based brake fluids.

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 gasoline and diesel contact.

Can it be used at high temperatures?
Yes, it is rated up to 400 degrees F, so it performs well in high-heat applications within that limit.

Will it resist weathering and ozone?
Yes, Viton offers good resistance to ozone and weathering, which helps in outdoor or exposed installations.