324 Viton O-Ring 75A Durometer 1-3/8 in ID 1-3/4 in OD Pack of 25

In this review the 324 Viton O-ring is evaluated for workshop and field use where chemical and heat resistance matter most. The bottom line: this pack of 25 black Viton seals is aimed at mechanics, gunsmiths, and equipment maintainers who need reliable, heat-resistant sealing that stands up to fuels and many solvents; the single biggest reason to buy is the material choice - Viton fluorocarbon elastomer - which provides broad chemical compatibility and high temperature tolerance uncommon in generic rubber O-rings.

Key Features

• Material: Made from Viton fluorocarbon elastomer, the O-ring offers strong resistance to fuels, oils, and many solvents for longer service life.
• Temperature range: Rated from -15 degrees F to 400 degrees F, it handles hot engine compartments and many industrial heating applications.
• Durometer: A 75A hardness gives a firm seal that resists penetration and extrusion while maintaining elasticity for repeated use.
• Form factor: Round cross-section ensures a dependable seal between cylindrical overlapping surfaces like shafts, housings, and threaded joints.
• Standards: Manufactured to the AS568A size standard, it fits common 324-size grooves and replacement tasks without guesswork.
• Pack quantity: Supplied as a pack of 25, useful for maintenance kits, multiple repairs, or stocking workshop spares.

Who It's For

This O-ring is best for technicians, hobbyists, and maintenance teams who service fuel systems, hydraulic fittings, suppressors, or small pumps and need a seal that resists heat and many chemicals. It is also a good choice for anyone replacing worn barrel seals, fuel bottle caps, or other cylindrical seals where the AS568A 324 size is required.

Those who should look elsewhere include users who need compatibility with strong alkalis, ammonia, certain glycol-based brake fluids, or super-heated steam, since Viton can be vulnerable to these specific media. For very soft or silicone-like sealing needs a lower durometer elastomer may be preferable.

Pros & Cons

Pros

• Excellent chemical and fuel resistance due to Viton composition, reducing premature failure in contact with oils and aromatic hydrocarbons.
• Wide usable temperature window up to 400 degrees F, suitable for high-heat locations and hot fluids.
• Good durability and fit reported by customers in applications like Remington 1100 barrel seals and fuel bottles, offering value in a 25-pack.
• Consistent sizing to AS568A makes replacements straightforward for common equipment.

Cons

• Not compatible with low molecular weight organic acids, ammonia gas, strong alkalis, certain brake fluids, or super-heated steam, which limits use in some specialty chemical systems.
• The 75A hardness is firm; it may not be ideal where an unusually soft or very compliant seal is required.

Specifications

Material	Viton (fluorocarbon elastomer)
Color	Black
Inner diameter (ID)	1-3/8 in
Outer diameter (OD)	1-3/4 in
Cross-section width	3/16 in
Durometer	75A
Temperature range	-15 degrees F to 400 degrees F

Our Verdict

The 324 Viton O-ring pack is recommended for mechanics, gunsmiths, and maintenance professionals who need a heat- and fuel-resistant replacement that fits AS568A 324 grooves. It offers solid durability and chemical resistance for most fuel and petroleum applications and represents good value in a 25-pack, but avoid it where exposure to ammonia, strong alkalis, or glycol brake fluids is expected.

Frequently Asked Questions

Will this fit standard 324 grooves?
Yes. The O-ring conforms to the AS568A 324 size and will fit standard grooves and housings made for that size.

Can it be used on fuel system components?
Yes. The Viton material is compatible with many fuels, aromatic and aliphatic hydrocarbons, and non-flammable hydraulic fuels, making it suitable for many fuel system seals.

Is it resistant to high heat?
Yes. It is rated for use up to 400 degrees F and performs well in high-temperature environments within that range.