Mr O-Ring 264 Viton O-Ring 90A 7-1/2in ID Pack of 5 - High Temp Seal

In this review the Mr O-Ring 264 Viton O-Ring pack is evaluated for mechanics, fabricators and maintenance techs who need a reliable high-temperature seal. The bottom line: this pack of five 90A durometer fluorocarbon o-rings stands out for heat and chemical resistance, making it a practical choice where petroleum products, fuels, silicone oils or strong solvents are present. The review focuses on durability in demanding environments and whether the nominal AS568 sizing and measured dimensions give a dependable fit in common industrial and plumbing applications.

Key Features

• Material: Made from Viton (FKM), the o-ring offers strong resistance to high temperatures, ozone and a wide range of chemicals so it lasts longer in harsh service conditions.
• Durometer: The 90A hardness provides a firm sealing surface that resists extrusion and deformation under pressure while still compressing to form an effective seal.
• Temperature range: Rated from -26C (-15F) to 232C (450F), these o-rings maintain sealing performance across extreme hot and cold cycles.
• Sizing: Nominal AS568 dimensions of 7-1/2in ID, 7-3/4in OD and 1/8in cross-section match measured actual and metric dimensions for predictable installation fit.
• Chemical compatibility: Performs well with petroleum, diesel, biodiesel blends, methanol or ethanol blends, mineral and silicone oils, and many solvents, reducing unexpected failures in mixed-fluids systems.

Who It's For

This product is suited for industrial maintenance teams, marine and automotive technicians, and anyone replacing or stocking large AS568-size o-rings where exposure to fuels, oils and high temperature air is expected. The pack of five is useful for projects and spare-part inventories where repeat replacements are likely.

Those who need very soft seals for low-pressure, highly conformable applications or who require FDA-grade food-contact certification should look elsewhere; this Viton 90A is optimized for industrial resistance and temperature tolerance rather than ultra-soft sealing or certified food service use.

Pros & Cons

Pros

• Excellent chemical and high-temperature resistance from the Viton (FKM) formulation for long service life in harsh environments.
• Firm 90A durometer reduces extrusion and maintains seal integrity under pressure, which is important for hydraulic and fuel systems.
• AS568 nominal sizing with close actual and metric measurements gives predictable fit for common standard housings and grooves.

Cons

• Higher hardness means less elasticity than softer elastomers, so it is not ideal where extreme conformability or low-mating-surface force is required.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	7-1/2in ID, 7-3/4in OD, 1/8in CS
Actual dimensions	7.484in ID, 7.762in OD, 0.139in CS
Metric dimensions	190.09 mm ID, 197.15 mm OD, 3.53 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack quantity	5

Our Verdict

The Mr O-Ring 264 Viton o-ring pack is a sensible buy for professionals who need a dependable, heat- and chemical-resistant seal in standard AS568 sizing. Its 90A hardness and measured dimensions deliver reliable fits and durability in petroleum, fuel and high-temperature applications, offering good value for maintenance kits and industrial spares where longevity and compatibility matter.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel blends?
Yes, the Viton formulation is specified as performing well with diesel and biodiesel blends, as well as many petroleum products.

Do the nominal AS568 sizes match the actual measured dimensions?
Yes, the product lists nominal AS568 sizing and close actual dimensions (7.484in ID, 7.762in OD, 0.139in CS) for predictable installation.

Can these be used at very low temperatures?
They are rated down to -26C (-15F), which is suitable for many cold environments but not for extreme cryogenic conditions.