Mr O-Ring 170 Viton O-Ring 90A Durometer 7-3/4in ID (Pack of 5)

In this review the Mr O-Ring 170 Viton O-Ring is assessed for technicians and hobbyists who need a small, reliable sealing solution that resists fuels and high temperatures. The bottom line: this pack of five 90A durometer Viton o-rings is best for applications exposed to petroleum products, high heat or ozone where material compatibility matters; the review finds they deliver consistent dimensions and long-term chemical resistance while fitting standard AS568 sizes.

Key Features

• Material: Viton (fluorocarbon FKM) offers excellent resistance to fuels, oils and many organic solvents for reliable sealing in harsh chemical environments.
• Hardness: 90A durometer provides a firm seal that holds shape under pressure while still compressing enough for typical flange and gland applications.
• Temperature range: Rated -26C (-15F) to 232C (450F) so it works in both low-temperature storage and very high temperature air or fluid systems.
• Pack size: Sold as a pack of five which helps service technicians keep spares on hand or replace multiple seals at once without reordering.
• Standard sizing: Nominal and actual dimensions align with AS568 expectations, making it straightforward to swap into standard o-ring grooves and hardware.
• Shelf life: Essentially unlimited under normal storage, so surplus rings remain usable over long maintenance cycles.

Who It's For

The Mr O-Ring 170 Viton is aimed at professionals in hydraulics, pneumatics and fuel systems, plus serious DIYers who need a small, durable o-ring for high-temperature or chemically aggressive environments. It is particularly useful where resistance to diesel, biodiesel blends, methanol or ethanol blends and mineral oils is required.

Those who should look elsewhere include users who need very soft seals for ultra-low compression sealing or who require food-grade or silicone-specific materials; for those needs different elastomers would be more appropriate.

Pros & Cons

Pros

• High chemical resistance from Viton makes it suitable for fuels, oils and many solvents.
• Wide operating temperature range supports high-heat applications up to 232C (450F).
• Accurate actual dimensions (7.737in ID, 7.943in OD, 0.103in CS) ensure predictable fit in AS568-sized grooves.
• Pack of five provides immediate spares for routine maintenance.

Cons

• 90A hardness is relatively firm and may not seal as well as softer compounds in very low-pressure, low-compression applications.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal dimensions	7-3/4in ID, 7-15/16in OD, 3/32in CS
Actual dimensions	7.737in ID, 7.943in OD, 0.103in CS
Metric dimensions	196.52 mm ID, 201.76 mm OD, 2.62 mm CS
Temperature range	-26C (-15F) to 232C (450F)
Pack quantity	5 rings

Our Verdict

The Mr O-Ring 170 Viton 90A in this pack of five is a smart choice for anyone needing a small o-ring that resists fuels, high temperatures and ozone while matching AS568 sizing. Its accurate dimensions, long shelf life and chemical compatibility make it good value for maintenance shops and field technicians who require dependable, long-lasting seals.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel?
Yes, Viton is compatible with diesel and many biodiesel blends and is formulated to resist petroleum products.

Do these rings meet standard AS568 sizes?
Yes, the product is offered to meet AS568 size standards with nominal and actual dimensions provided for accurate replacement.

What temperatures can these o-rings handle?
They are rated from -26C (-15F) up to 232C (450F), suitable for high-temperature sealing applications.