Mr O-Ring 352 Viton O-Ring 90A Durometer 4-7/8in ID Pack of 5

In this review the Mr O-Ring 352 Viton O-Ring is evaluated for installers and maintenance techs who need a durable, high-temperature seal in petroleum, fuel, and harsh chemical environments. The bottom line: this pack of five 90A durometer Viton o-rings stands out for its wide temperature range and chemical resistance, making it a reliable replacement part for hydraulic, fuel, and industrial sealing tasks where durability and compatibility matter most.

Key Features

• Material: Viton (fluorocarbon FKM) provides robust resistance to fuels, oils, many solvents and high temperature exposure, reducing seal failures in aggressive media.
• Hardness: 90A durometer gives a firm cross-section that holds shape under compression and is suitable for static and some dynamic sealing where firmer material is required.
• Size accuracy: Nominal 4-7/8in ID and 5-1/4in OD with actual dimensions listed ensures a close fit for AS568-based applications and easier part selection.
• Temperature range: Rated from -26C (-15F) to 232C (450F), allowing use from cold starts up to very high operating temperatures without rapid degradation.
• Chemical compatibility: Performs well in petroleum, diesel, biodiesel blends, methanol/ethanol blends, mineral oil, silicone grease, and many organic solvents, expanding its application range.
• Pack size: Supplied as a pack of five to cover multiple replacements or to keep spares on hand for routine maintenance.

Who It's For

This is a practical choice for industrial maintenance crews, automotive technicians, and anyone working with fuel systems, hydraulic equipment, or high-temperature seals who needs a durable, chemical-resistant o-ring that closely follows AS568 sizing. It is particularly useful where exposure to fuels, oils, ozone or high temperatures is expected.

Those who should look elsewhere include users who need very soft, low-durometer seals for low-pressure dynamic shafts, or applications requiring FDA food-grade or EPDM-specific compatibility; Viton is not ideal for some steam or highly alkaline cleaning processes.

Pros & Cons

Pros

• Excellent chemical and high-temperature resistance for long service life in aggressive fluids.
• 90A hardness maintains seal shape and compression set resistance in many static and semi-dynamic uses.
• Accurate actual and metric dimensions simplify replacement in AS568-sized grooves.
• Pack of five provides immediate spares for maintenance tasks.

Cons

• Higher 90A hardness may be too stiff for very low-pressure dynamic seals or delicate components.
• Viton is not suitable for some highly alkaline environments or certain steam-cleaning processes.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	4-7/8in ID, 5-1/4in OD, 3/16in CS
Actual dimensions	4.850in ID, 5.270in OD, 0.210in CS
Metric dimensions	123.19 mm ID, 133.85 mm OD, 5.33 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack quantity	5 o-rings

Our Verdict

For technicians who need a dependable, high-temperature, and chemically resistant seal, the Mr O-Ring 352 Viton 90A in a pack of five is a solid value; it matches AS568 sizing, offers wide compatibility with fuels and oils, and the 90A hardness suits many static and semi-dynamic sealing tasks where durability is the priority.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel blends?
Yes, Viton is rated for petroleum products including diesel and common biodiesel blends and performs well in those fluids.

Will the 90A hardness work for moving shafts?
90A is firmer than low-durometer seals and can work for some semi-dynamic uses, but it may be too stiff for low-pressure, high-wear dynamic shaft seals.

Do these follow standard AS568 sizes?
The product is manufactured to match AS568 size standards and provides both nominal and actual dimensions for accurate replacement.