M3x55 Viton O-Ring 75A Durometer, 55 mm ID - Durable Seal

In this review the M3x55 Viton O-Ring is judged on durability and chemical resistance for industrial sealing tasks; it is best for users who need a reliable, heat- and fuel-resistant seal in a compact size. The bottom line: this pack of 50 black Viton rings is a practical choice when compatibility with a range of hydrocarbons and non-flammable hydraulic fluids matters, and when a 75A durometer offers the right balance of softness and resilience for thread protection and small cylinder seals.

Key Features

• Material: Made of Viton fluorocarbon elastomer for broad chemical and fuel resistance useful in many service environments.
• Temperature range: Rated for a wide range of temperatures so it holds seals from low-temperature service to high-heat applications.
• Durometer: 75A hardness gives a durable but flexible seal that performs well on threaded barrels and small fittings.
• Geometry: Round cross-section provides a consistent seal between overlapping cylindrical surfaces for simple installations.
• Pack quantity: Supplied as a pack of 50, which is convenient for maintenance shops or repeated replacements without frequent reordering.

Who It's For

The M3x55 Viton O-Ring is aimed at technicians, hobbyists, and maintenance crews who work with hydraulic fittings, fuel systems, or threaded barrels where chemical resistance and heat tolerance are important. It suits users needing a mid-hardness seal that holds thread protectors in place or replaces small carburetor and barrel seals.

It is not ideal for systems exposed to strong alkalis, ammonia gas, or glycol-based brake fluids, or where exposure to super-heated steam or low molecular weight organic acids is expected; those users should select a different elastomer tailored for those chemistries.

Pros & Cons

Pros

• Strong chemical and fuel resistance from the Viton compound performs well with aromatic and aliphatic hydrocarbons.
• Firm but flexible 75A durometer balances sealing force and longevity for threaded and small sealing surfaces.
• Pack of 50 offers good value for routine maintenance and multiple replacements.
• Works effectively at elevated temperatures and in high vacuum contexts where applicable.

Cons

• Viton is vulnerable to certain chemicals (amines, strong alkalis, some brake fluids), so compatibility checks are required for exotic fluids.
• The 55 mm ID size is specific; buyers needing other diameters must verify fit before purchase.

Specifications

Our Verdict

The M3x55 Viton O-Ring is a solid choice for routine sealing tasks where chemical and heat resistance matter, and the 75A hardness makes it versatile for threaded barrels and small cylinder seals. For workshops and technicians who replace seals regularly, the pack of 50 is economical and dependable, provided the application avoids chemicals known to attack Viton.

Frequently Asked Questions

Will this O-ring resist fuel and hydraulic fluids?
Yes; Viton is compatible with many fuels and non-flammable hydraulic fluids, including aromatic and aliphatic hydrocarbons.

Is this size suitable for thread protector use?
Customers report the 55 mm ID fits common threaded barrels and works well to keep thread protectors in place, but measure your part to confirm fit.

Can it be used with brake fluid or ammonia?
No; Viton is vulnerable to glycol-based brake fluids, ammonia gas, and certain amines, so choose a different material for those exposures.