259 EPDM O-Ring 70A Durometer 6-1/4 in ID Pack of 25 - Reliable Seal

In this review the 259 EPDM O-Ring (70A durometer, pack of 25) is assessed for workshop and maintenance use; the bottom line is that it is a dependable, general-purpose sealing option for applications exposed to weather, ozone and many common fluids. The reviewer found the nominal 6-1/4 in ID and 1/8 in cross-section dimensions to match standard AS568 sizing closely, and its EPDM compound excels where steam resistance, water handling and resistance to dilute acids and alkalies are required, making it a practical choice for technicians who need bulk, consistent sizes for routine service work.

Key Features

• Material and hardness: The EPDM compound at 70A durometer provides a good balance of flexibility and resilience for static and low-dynamic seals.
• Temperature range: Rated from -55C to 125C, it covers many outdoor and process temperature demands while remaining flexible in cold conditions.
• Chemical compatibility: Performs well with water, alcohols, dilute acids and alkalis, phosphate ester hydraulic fluids and many silicone oils and greases, expanding its practical uses.
• Size accuracy: Nominal 6-1/4 in ID, 6-1/2 in OD and 1/8 in cross-section closely match the actual measurements for consistent interchange with AS568 sizes.
• Bulk pack: Supplied in packs of 25, which reduces shopping frequency for frequent rebuilds and field spares.
• Durability: Excellent resistance to ozone, sunlight and weathering means long outdoor storage life and reliable field performance.

Who It's For

This product suits maintenance technicians, plumbers and small shops that require a reliable, weather-resistant sealing option in a common large o-ring size. The pack-of-25 format works well for routine rebuilds, gasket replacement kits and field service trucks where stocking multiple spares is needed.

It is less appropriate for precision dynamic rotary seals in aggressive hydrocarbon environments or where specialty elastomers (like fluorocarbon or nitrile with high oil resistance) are required; buyers needing compatibility with strong solvents, fuels or high-pressure rotary shafts should look for a compound rated for those specific fluids.

Pros & Cons

Pros

• Good weather and ozone resistance makes these o-rings suitable for outdoor and aging-prone installations.
• Sized to AS568-like standards with close actual dimensions for straightforward replacement.
• Broad chemical compatibility with water, steam, alcohols and dilute acids allows flexible use across many maintenance tasks.

Cons

• Not ideal for continuous exposure to strong hydrocarbons or fuels where alternative elastomers would be better.

Specifications

Our Verdict

The 259 EPDM O-Ring 70A in a 25-pack is a practical, cost-effective choice for general sealing tasks where weather resistance and good low-temperature flexibility matter. For general maintenance, plumbing and many hydraulic or steam applications it offers solid value, though installers working with aggressive hydrocarbons should choose a different compound.

Frequently Asked Questions

Are these o-rings compatible with petroleum oils?
EPDM is not recommended for prolonged contact with petroleum oils and fuels; for those fluids choose a nitrile or fluorocarbon material.

Do the sizes follow standard AS568 sizing?
Yes, the nominal and actual dimensions closely match AS568 259 size standards for straightforward replacements.

How long can these be stored?
EPDM offers excellent resistance to ozone and weathering and the shelf-life is effectively unlimited when stored in cool, dark conditions.