Industry Solutions
01
EPDM O-Ring Lubricating Oil Compatibility
2025-07-14
Case Study:Are you struggling to find the right grease for your EPDM seals?
Are you struggling to find the right grease for your EPDM seals?Are you also experiencing seal expansion issues?
Do you also meet same situation when the valve is in a static position for a duration of time, and then It become difficult to move?
In fact, these are the problems that our sealing ring customers often encounter.
This is a critical incompatibility that can lead to a series seal failure or even worse, it will damage your seal. damage your seals.
Let us understand the compatibility relationship between EPDM and various lubricants first.
● EPDM and PAO polyalphaolefin) base oil greases are incompatible.
1. PAO molecules have excellent solvency properties that penetrate EPDM polymer chains.This causes significant swelling (typically 20-40% volume increase)
2. The swelling leads to seal distortion, groove binding, and loss of sealing effectiveness.
3. EPDM's saturated polymer backbone makes it particularly susceptible to PAO absorption.
● Mineral Oil - Excellent compatibility, minimal swelling (<5%).
● PAG (Polyalkylene Glycol) - Good compatibility, slight swelling (5-10%).
● Diester/Polyol Ester - Good compatibility, low swelling.
● Silicone - Good compatibility, moderate swelling (10-15%).
● Silicone - Good compatibility, moderate swelling (10-15%).
| Base Oil Type | EPDM Status | Effect on EPDM | Alternative Elastomer | Recommended Products |
|---|---|---|---|---|
| PAO (Polyalphaolefin) | Incompatible | Severe swelling | NBR, FKM (Viton) | / |
| Mineral Oil | Compatible | Minimal swelling | EPDM Preferred | FRTLUBE General Purpose Silicone Grease -SG11J O ring silicone grease |
| PAG (Polyalkylene Glycol) | Compatible | Slight swelling | EPDM Suitable | FRTLUBE PAG O ring silicone grease -PG221A |
| silicone | Limited Use | Moderate swelling | EPDM or VMQ | FRTLUBE food grade O ring silicone grease -SG550 |
| Ester (Diester/Polyol) | Compatible | Lowswelling | EPDM Suitable | FRTLUBE food grade valve grease-SG701 |
● Use NBR (Nitrile) O-rings for general applications (-40°C to +120°C).
● Use FKM (Viton) O-rings for high-temperature applications (-20°C to +200°C).
● Consider HNBR for extreme temperature/chemical resistance.
Performance Comparison
Temperature Ranges:
1.Mineral oil + EPDM: -40°C to +150°C
2.PAG + EPDM: -30°C to +180°C
3.PAO + NBR: -40°C to +120°C
4.PAO + FKM: -20°C to +200°C
Service Life Considerations:
● EPDM with compatible oils: 5-10 years typical service life
● EPDM with PAO: Failure within months due to swelling
● NBR/FKM with PAO: Extended service life due to compatibility
1. Never assume compatibility - Always consult compatibility charts.
2. Perform swell testing for critical applications.
3. Consider system contamination - Mixed lubricants can cause unexpected reactions.
4. Temperature cycling effects - Swelling can be accelerated by thermal cycling.
5. Seal groove design - Must accommodate any allowable swelling.
This incompatibility is one of the most common causes of unexpected seal failure in industrial applications. Always verify elastomer-lubricant compatibility through manufacturer data or testing before final selection.