109 Viton O-Ring 90A 5/16in ID 1/2in OD Pack of 500 - High Temp Seal

In this review the focus is on a workhorse sealing part: the 109 Viton O-Ring in a bulk pack of 500. This product is aimed at technicians, maintenance shops, and builders who need consistent, high temperature resistant seals for fuel systems, hydraulic connections, or equipment exposed to oils and solvents. The single biggest reason to buy is predictable chemical and temperature resistance from a 90A durometer FKM compound supplied in a standard AS568 size, which keeps replacement simple and inventory costs low.

Key Features

• Material: The FKM Viton compound resists high temperatures, fuels and many solvents so seals last longer in demanding environments.
• Hardness: The 90A durometer gives a firm cross-section that maintains a reliable compression seal under pressure and repeated cycles.
• Size accuracy: Nominal and actual dimensions are provided so buyers can confirm fit; the actual ID is 0.299in and OD is 0.505in for consistent installations.
• Wide temperature range: Rated from -26C (-15F) to 232C (450F), this o-ring suits applications from low-temperature service up to very high operating heat.
• Chemical versatility: Performs well with petroleum, diesel, biodiesel blends, methanol or ethanol blends and mineral or silicone oils, reducing part variation needs.
• Bulk pack: Supplied as a pack of 500 which is cost effective for shops and maintenance programs that consume parts regularly.

Who It's For

This o-ring is well suited to mechanics, hydraulics shops, and OEM maintenance teams who replace seals frequently and need an FKM solution that meets AS568 sizing standards. The bulk pack equals lower unit cost and ensures compatible spares are on hand for fuel systems, pumps, and high temperature seals.

Those who should look elsewhere include applications requiring food-grade or peroxide-cured silicone seals, extremely soft elastomers for low-pressure static seals, or exotic chemical compatibility beyond typical hydrocarbons and common solvents. For those use cases choose a material specified for that chemistry.

Pros & Cons

Pros

• Excellent high temperature and chemical resistance from the Viton (FKM) formulation.
• Reliable dimensional data with both nominal and actual measurements for accurate selection.
• 90A hardness provides durable sealing under pressure and repeated cycles.
• Large 500-count pack reduces per-unit cost and keeps shops stocked.

Cons

• Not suitable where food-grade or very soft elastomers are required due to its FKM compound and 90A hardness.

Specifications

Material	Viton (FKM)
Durometer	90A
Nominal Dimensions	5/16in ID, 1/2in OD, 3/32in CS
Actual Dimensions	0.299in ID, 0.505in OD, 0.103in CS
Metric Dimensions	7.59 mm ID, 12.83 mm OD, 2.62 mm CS
Temperature Range	-26C (-15F) to 232C (450F)
Pack Quantity	500

Our Verdict

The 109 Viton O-Ring in a 500 pack is a practical choice for workshops and maintenance teams that need reliable, high temperature and chemical resistant seals in a common AS568 size. It is good value for anyone replacing fuel system and hydraulic seals regularly, though not intended for food-grade or extremely low durometer requirements.

Frequently Asked Questions

Are these o-rings compatible with diesel and biodiesel blends?
Yes. The Viton compound is specified to perform well with diesel and diesel blended with biodiesel.

Do the listed dimensions reflect actual measured size?
Yes. The product lists both nominal (5/16in ID, 1/2in OD) and actual dimensions (0.299in ID, 0.505in OD, 0.103in CS) for accurate fit confirmation.

Is this material suitable for very high temperature applications?
Yes. The o-ring is rated up to 232C (450F) and is intended for high temperature resistance.