EPDM O-Rings: When You Should (and Shouldn’t) Use Them

EPDM isn’t the first O-ring material most people think of — but in the right applications, it’s unbeatable. If you’re working with water, steam, outdoor equipment or brake systems, EPDM is often the safest and most reliable choice.

Here’s everything you need to know before choosing EPDM O-rings.

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What Are EPDM O-Rings?

EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber known for its exceptional resistance to:

• Water

• Steam

• Weathering & UV

• Brake fluids (glycol-based)

• Ozone & outdoor exposure

It performs where most other rubbers fail — especially nitrile (NBR).

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EPDM O-Ring Temperature Range

One of EPDM’s biggest strengths is its ability to stay flexible in both hot and cold environments:

Typical range:
−40 °C to +150 °C

This makes it ideal for systems that run hot (steam, heating systems) or equipment exposed to freezing conditions.

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Where EPDM O-Rings Work Best

EPDM is the go-to material for:

✓ Water-based systems

• Plumbing

• Washing machines

• Water pumps

• Valves & fittings

✓ Steam applications

• Boilers

• Heating systems

• Sterilisation equipment

✓ Automotive brake systems

EPDM is highly resistant to glycol-based brake fluids — something NBR and FKM cannot handle.

✓ Outdoor sealing

EPDM resists sunlight, ozone and weathering better than NBR or even silicone.

If you’re sealing water, steam or brake fluid, EPDM is almost always the correct choice.

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Where NOT to Use EPDM O-Rings

Here’s where EPDM fails — and where you should choose NBR or FKM instead:

❌ Petroleum-based oils

EPDM swells and breaks down in:

• Engine oil

• Gearbox oil

• Hydraulic oil

• Fuels

❌ Grease & lubricants

Anything petroleum-based causes issues.

❌ Hydrocarbons & solvents

For chemical and fuel resistance, use FKM (Viton®) instead.

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EPDM vs Other O-Ring Materials

A quick comparison:

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Do You Need EPDM O-Rings?

If your system involves:

• Water or steam

• Outdoor weather exposure

• Glycol brake fluid

• High or low temperatures

…then EPDM is likely the safest and longest-lasting option.

Shop our EPDM o-rings here: EPDM O-Rings – Water, Steam & Brake Fluid Seals | SealWithSelo – Seal with Selo