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Should I use EPDM or nitrile rubber?
The deciding question is oil. Use nitrile (NBR) for petroleum oils, fuels, greases and hydraulic fluid; EPDM swells and fails in them. Use EPDM for weather, ozone, water, steam, glycol coolant and glycol brake fluid, where nitrile cracks or degrades. EPDM also runs hotter, to about 300 °F (150 °C) versus 212 °F (100 °C) for standard nitrile.
EPDM rubber
Nitrile rubber (NBR)
By the numbers
Priced on the same representative part: extruded seal, rubber, 5,000 pcs.
Tensile strengthMPa
EPDM
12
NBR
14
Densityg/cm³
EPDM
1.15
NBR
1.2
Max service temp°C
EPDM
150
NBR
100
Elongation%
EPDM
300
NBR
300
Raw material cost$/kg
EPDM
5
NBR
5
Which should you pick?
Pick EPDM when
- Parts face sun, ozone and weather
- They see hot water, steam or glycol coolant
- The fluid is glycol-based brake fluid
- The part is an HVAC, appliance or washer gasket
Pick NBR when
- The fluid is petroleum oil, fuel, grease or hydraulic fluid
- The part is a hydraulic or pneumatic O-ring
- Dynamic seals need abrasion and tear resistance
- Grommets, diaphragms or gaskets must resist oil
Key differences
| EPDM | NBR | |
|---|---|---|
| Petroleum oil and fuel | Swells and fails | Excellent resistance |
| Ozone, UV and weather | Excellent | Poor; cracks outdoors unprotected |
| Glycol brake fluid | Compatible | Attacked |
| Ketones | Generally resistant | Attacked |
| Abrasion and tear | Lower | Good; suits dynamic seals |
| Upgrade path | Peroxide-cured grades for heat | HNBR to about 300 °F (150 °C), or FKM |
Questions
Can EPDM be used with oil?
No. EPDM swells and loses strength in petroleum oils, fuels and most hydrocarbon solvents. Use nitrile for oils and fuels, or FKM for hot oils and aggressive fuels. EPDM is fine with water, steam, glycol and glycol-based brake fluid.
Is nitrile rubber good outdoors?
Not by itself. Ozone and UV crack standard NBR. Use EPDM or neoprene for weather exposure, or specify an ozone-resistant NBR/PVC blend or HNBR if oil resistance is also needed.
Which is cheaper, EPDM or nitrile?
They are similar in compound cost, and both are low-cost elastomers. Choose on fluid and environment, not price: the wrong one fails quickly.
What if a seal sees both oil and weather?
Neoprene balances moderate oil resistance with good weather resistance. For heavier oil exposure outdoors, HNBR or an NBR/PVC blend is the step up, and FKM covers heat as well.
Try both on your part.
The builder prices the same geometry in every suitable process and material, with DFM for each.