Mr O-Ring 374 Viton O-Ring 90A Durometer 9-1/4 in ID Pack of 5

In this review the focus is on a hardworking sealing option for demanding environments: the Mr O-Ring 374 Viton O-Ring in a pack of five. The bottom line is simple - this is for technicians, mechanics and maintenance teams who need a compact supply of reliably high-temperature and chemical-resistant o-rings. The reviewer found the 90A durometer Viton compound delivers dependable compression resistance and broad chemical compatibility, making these o-rings a practical choice when replacing seals exposed to fuels, oils or high heat.

Key Features

• Material: Viton FKM construction offers excellent resistance to high temperature, ozone and many automotive and industrial fluids.
• Hardness: 90A durometer provides a firm seal that resists extrusion while still conforming to grooves under typical service loads.
• Size accuracy: Nominal and actual dimensions are listed so fit can be checked precisely before installation.
• Temperature range: Rated from -26C to 232C, suitable for very hot operating conditions and intermittent thermal cycling.
• Chemical compatibility: Performs well with petroleum, diesel, biodiesel blends, methanol or ethanol mixes, mineral oils and many solvents.
• Pack quantity: Supplied as a pack of five, convenient for small repairs or stocking common replacement sizes.

Who It's For

This Viton o-ring is aimed at HVAC technicians, automotive mechanics and industrial maintenance staff who routinely encounter fuels, hydraulic fluids or elevated temperatures and need a resilient, long-lasting seal. The pack of five is ideal for field service kits or small shops that perform occasional seal replacements and value predictable material performance.

Users who need extremely soft seals for low-pressure static applications or who require food-grade elastomers should look elsewhere, since this is a 90A hard FKM intended for demanding chemical and thermal environments rather than delicate sealing or regulatory food-contact uses.

Pros & Cons

Pros

• High temperature tolerance up to 232C makes these o-rings suitable for hot engine or process applications.
• Viton FKM material offers broad resistance to fuels, oils, ozone and many solvents encountered in industrial settings.
• 90A durometer gives a firm, durable seal that resists extrusion and maintains shape under pressure.
• Pack of five provides enough spares for multiple repairs without excess inventory.

Cons

• The 90A hardness may be too stiff for very low-pressure or delicate sealing tasks that need a softer compound.
• Not suitable for food-contact or applications requiring specialized regulatory certifications.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	9-1/4 in ID, 9-5/8 in OD, 3/16 in CS
Actual dimensions	9.225 in ID, 9.645 in OD, 0.210 in CS
Metric dimensions	234.32 mm ID, 244.98 mm OD, 5.33 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack quantity	5 o-rings

Our Verdict

The Mr O-Ring 374 Viton 90A o-ring is a pragmatic choice for professionals who need a robust, chemically resistant seal that endures high temperatures. It represents good value as a pack of five for repair and maintenance work where FKM performance is required, though those needing softer or food-grade elastomers should choose a different compound.

Frequently Asked Questions

Are these o-rings suitable for fuel systems?
Yes, the Viton FKM compound is compatible with petroleum, diesel and many fuel blends, making these suitable for fuel system sealing when size fits.

Will the 90A hardness work in hydraulic equipment?
In many hydraulic applications the 90A hardness provides durable sealing and extrusion resistance, but check groove clearance and pressure conditions before use.

How accurate are the listed sizes?
The product lists both nominal and actual dimensions so installers can confirm fit; actual ID and OD measurements are provided for precise selection.