329 Viton O-Ring 2in ID 75A Pack of 25 - Chemical & Heat Resistant

In this review the 329 Viton O-Ring (2in ID, 75A durometer) is evaluated as a practical replacement seal for industrial and hobby applications where chemical and heat resistance matter. The bottom line: this pack of 25 is for anyone needing reliable, repeatable seals that tolerate fuels, aromatic and aliphatic hydrocarbons, and high temperatures up to 400 degrees F. The reviewer found the rings offer consistent dimensions, good leak resistance in cylinder overlaps, and solid durability for applications like fuel bottle seals, firearm barrel seals, and other small hydraulic or vacuum uses.

Key Features

• Material: Made from Viton fluorocarbon elastomer to resist fuels, many chemicals, ozone, and weathering for long service life.
• Temperature range: Rated from -15 degrees F to 400 degrees F, providing reliable sealing in hot engine or heated-fluid environments.
• Durometer: 75A hardness gives a balance of flexibility and resistance to penetration useful for static and some dynamic seals.
• Form factor: Round cross-section and precise 2in ID with 2-3/8in OD dimensions make it suitable for cylindrical overlapping surfaces and common replacement needs.
• Standards: Manufactured to the AS568A sizing standard so sizes match common O-ring dimensions used in industry and plumbing.
• Value pack: Supplied in a pack of 25 which keeps spares on hand for maintenance and replacement without frequent reordering.

Who It's For

These O-rings are aimed at technicians, hobbyists, and maintenance personnel who need chemical- and heat-resistant seals for non-flammable hydraulic fuels, silicone oils, and various hydrocarbons. They work well as replacements on MSA fuel bottles, Remington barrel seals, Silencerco switchback parts, and similar cylindrical assemblies.

Users who require resistance to low molecular organic acids, ammonia gas, strong alkalis, amines, glycol-based brake fluids, or super-heated steam should look for a different elastomer, since Viton is vulnerable to those specific media.

Pros & Cons

Pros

• Consistent fit and dimensions that customers report work well for common replacement tasks.
• Excellent heat and fuel resistance makes these reliable in hot or hydrocarbon-exposed environments.
• Good durability and leak resistance when seated correctly in cylindrical overlaps.
• Pack of 25 offers strong value for repair kits and spare inventories.

Cons

• Not compatible with certain chemicals like ammonia, amines, alkalis, and glycol-based brake fluids, limiting use in some specialty systems.
• 75A hardness may be firmer than needed for some very low-pressure static seals where a softer compound is preferred.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inside diameter (ID)	2 in
Outside diameter (OD)	2-3/8 in
Cross-section width	3/16 in
Durometer	75A
Temperature range	-15 degrees F to 400 degrees F

Our Verdict

The 329 Viton O-Ring pack is a pragmatic choice for anyone needing robust, heat- and fuel-resistant seals in cylindrical applications. It is good value as a pack of 25, meets AS568A sizing, and performs reliably in common replacement roles, though users handling ammonia, amines, or glycol fluids should choose a different material.

Frequently Asked Questions

Are these O-rings compatible with gasoline and diesel?
Yes, Viton is compatible with many fuels and aromatic and aliphatic hydrocarbons, making these suitable for many fuel-related seals.

Will the 75A hardness work for dynamic shafts?
75A is better suited to static seals and light dynamic service; very dynamic or reciprocating shafts may need a different formulation or lower durometer.

Do these rings follow standard sizing so replacements fit?
Yes, they are made to AS568A sizing so they match common O-ring dimension standards for easy replacement.