328 Viton O-Ring 75A Durometer 1-7/8in ID 2-1/4in OD - Pack of 25

In this review the 328 Viton O-ring pack is judged as a practical replacement option for technicians and hobbyists who need reliable sealing in hot, chemical-exposed environments. The bottom line: buy this pack if you need a consistent, heat- and chemical-resistant seal in applications ranging from fuel fittings to vacuum systems, because the Viton compound and 75A durometer deliver durability and leak resistance without the premium cost of specialty parts.

Key Features

• Material: Made of Viton fluorocarbon elastomer, this O-ring resists many fuels and chemicals typically encountered in hydraulic and fuel-system service, reducing material degradation over time.
• Temperature range: Rated from -15 degrees F to 400 degrees F, the ring is suitable for high-heat engine bays and heated process lines while still performing in cold conditions.
• Durometer: The 75A hardness provides a balance of resilience and resistance to penetration, helping sustain a reliable seal under static compression.
• Form factor: Round cross-section and precise dimensions ensure a proper seal between overlapping cylindrical surfaces such as bottle necks, barrels, and fittings.
• Standards: Conformance to Aerospace Standard AS568A sizing means these O-rings match common industry replacement dimensions for straightforward swaps.
• Pack size: Supplied as a pack of 25, the set offers spare parts on hand for maintenance cycles or multiple installations, saving trips for single replacements.

Who It's For

This product suits maintenance techs, gunsmiths, and DIY mechanics who service fuel bottles, hydraulic fittings, or devices exposed to fuels and aromatic hydrocarbons and need a resilient replacement O-ring in a common size. The pack is particularly useful where multiple identical seals are required or where parts are consumed during routine servicing.

Those working with strong alkalis, ammonia, glycol-based brake fluids, or super-heated steam should look elsewhere or confirm chemical compatibility before use, since Viton is vulnerable to those specific substances and may degrade if exposed.

Pros & Cons

Pros

• Excellent heat and chemical resistance for fuels, aromatic and aliphatic hydrocarbons, and many solvents.
• Consistent sizing to AS568A makes replacements easy and predictable for common assemblies.
• Good value: a 25-pack provides spares and reduces downtime during maintenance.
• Customers report dependable fit and leak resistance in real-world uses such as fuel bottles and firearm seals.

Cons

• Not compatible with low molecular organic acids, ammonia, certain alkalis, or glycol-based brake fluids, limiting use in some chemical systems.
• 75A hardness may be firmer than desired for very low-pressure dynamic seals where softer compounds are preferred.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner Diameter (ID)	1-7/8 in
Outer Diameter (OD)	2-1/4 in
Width (Cross-section)	3/16 in
Durometer	75A
Temperature Range	-15 degrees F to 400 degrees F

Our Verdict

The 328 Viton O-ring pack is a sensible buy for anyone needing robust, heat- and fuel-resistant replacements in a common AS568A size. It provides dependable sealing and good value for maintenance kits, though users must verify compatibility when exposed to acids, amines, or glycol-based fluids.

Frequently Asked Questions

Are these O-rings suitable for fuel applications?
Yes; Viton is compatible with many fuels, aromatic and aliphatic hydrocarbons, and is commonly used in fuel-system seals.

What temperatures can they handle?
They are rated from -15 degrees F to 400 degrees F, making them usable in both cold and high-heat environments.

Will they work with brake fluid or ammonia?
No; Viton is vulnerable to glycol-based brake fluids and ammonia gas, so these exposures should be avoided.