Mr O-Ring 342 Viton O-Ring 90A Durometer, 3-5/8 in ID - Pack of 10

In this review the Mr O-Ring 342 Viton O-Ring is evaluated for users who need a high-temperature, fuel-resistant seal in a common AS568 size. The bottom line: this pack of 10 delivers robust chemical and heat resistance thanks to its 90A durometer fluorocarbon compound, making it a reliable choice for equipment exposed to petroleum, diesel blends, silicone oils, and high vacuum environments. For technicians and maintenance buyers who need consistent dimensions and long shelf-life, this o-ring is an economical way to stock a proven sealing material.

Key Features

• Material: The Viton fluorocarbon rubber offers broad chemical resistance, so it holds up to fuels, oils and many organic solvents without rapid degradation.
• Temperature range: Rated from -26C to 232C, it sustains sealing performance in both cold service and very high temperature air applications.
• Durometer: The 90A hardness balances compression resistance with conformability for durable static and dynamic seals under moderate extrusion risk.
• Pack size: Supplied as a pack of 10, it provides spares for routine maintenance or multiple installations without buying oversized quantities.
• Dimensional accuracy: Nominal and actual dimensions are provided so installers can confirm fit; the close actual ID and OD reduce guesswork when replacing seals.
• Standards: Sized to meet AS568 conventions, making these o-rings compatible with many existing housings and grooves.

Who It's For

This o-ring is aimed at industrial and maintenance technicians, hydraulic and fuel-system professionals, and anyone who needs a compact, high-temperature seal for engines, pumps, or fittings. It is especially useful where exposure to petroleum products, biodiesel blends, or silicone oils is expected and a long shelf-life is valued.

Those who should look elsewhere include users needing extreme low-temperature elastomers below -26C, or applications that require very soft, low-durometer seals for delicate compression - a softer compound would perform better in those niche cases.

Pros & Cons

Pros

• Excellent chemical resistance makes it suitable for fuels, oils and many solvents encountered in automotive and industrial systems.
• Wide operating temperature span from -26C to 232C supports both hot engine compartments and heated process lines.
• Pack of 10 gives a cost-effective supply for maintenance and multiple installations.
• Actual dimensions are listed so fitment can be checked before installation, reducing returns or reorders.

Cons

• At 90A durometer the o-ring is relatively firm, which may not be ideal for very low-pressure or soft-sealing applications.
• Viton can be more expensive than generic rubbers, so price-sensitive buyers with benign media may prefer cheaper alternatives.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	3-5/8 in ID, 4 in OD, 3/16 in CS
Actual dimensions	3.600 in ID, 4.020 in OD, 0.210 in CS
Metric dimensions	91.44 mm ID, 102.10 mm OD, 5.33 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack	Pack of 10

Our Verdict

The Mr O-Ring 342 Viton 90A in a pack of 10 is a dependable, well-specified choice for industrial and automotive sealing where chemical and high-temperature resistance matter. Its accurate dimensions and AS568 sizing make it practical for maintenance stock, and the long temperature range offers versatility. Choose this pack when durability in fuel or oil exposure is required; consider a softer or lower-cost compound only if your application demands it.

Frequently Asked Questions

Can these o-rings handle gasoline and diesel?
Yes, Viton is rated for petroleum products and diesel blends, making these o-rings suitable for fuel-exposed seals.

Are the dimensions exact for AS568 fittings?
The product lists nominal and actual dimensions and is produced to match AS568 size standards, allowing you to confirm fit before installation.

How long can these be stored?
Viton has effectively unlimited shelf-life under normal storage conditions, so the pack of 10 can be kept as spares without concern.