EPDM O-Ring
EPDM (Ethylene Propylene Diene Monomer) rubber is widely used in automotive cooling and HAVC systems because of its good resistance to coolant water, low temperature and heat.
Table of content
- EPDM Material Property
- O-RING Size Calculation
- Working Temperature Range
- Chemical Resistance
- O-Ring Lubrication
- O-Ring Color
- Typical Applications
EPDM Material Property
| Characteristic | Unit | Test Method | Specification | Result (A) | |||||
| 1 | Tensile strength | MPa | ISO 37 | 12 min | 15 | ||||
| 2 | Elongation | % | ISO 37 | 200 min | 280 | ||||
| 3 | Tear strength | N/mm | ISO 34-1 a | 4 min | 4.8 | ||||
| 4 | Compression set 24 hrs at 125℃ Method A-Type B | % | ISO815-1 | 15 max | 10 | ||||
| 5 | Heat ageing 42 days at 125℃ Shore A Hardness Shore A Hardness change Tensile strength Elongation | Point Point MPa % | ISO 188 | ±6 | 73 +5 15.5 275 | ||||
Working Temperature Range
Temperature range : –60°C to 150°C
Chemical Resistance
| Chemical Resistance of EPDM Rubber | |||||
| Chemical Type | Examples | Concentration | Temperature Limit | Resistance Rating | Notes |
| Inorganic Acids | |||||
| Sulfuric Acid (H₂SO₄) | Dilute | ≤70% | ≤60°C | Good | Avoid >70% concentration or >80°C (swelling/degradation). |
| Hydrochloric Acid (HCl) | Dilute | ≤30% | ≤60°C | Good | >30% or >80°C causes corrosion. |
| Nitric Acid (HNO₃) | Dilute | ≤10% | ≤50°C | Moderate | >10% or >50°C leads to rapid oxidation. |
| Phosphoric Acid (H₃PO₄) | All | Any | ≤100°C | Excellent | Full concentration range tolerated. |
| Organic Acids | Acetic Acid, Citric Acid | <30% | ≤80°C | Good | High concentrations (>30%) or >80°C may cause swelling. |
| Alkaline Media | |||||
| Sodium Hydroxide (NaOH) | ≤50% | ≤100°C | Excellent | >50%: Limit to ≤80°C. | |
| Potassium Hydroxide (KOH) | ≤50% | ≤100°C | Excellent | Slight hardening at >120°C. | |
| Ammonia (NH₃·H₂O) | Any | ≤80°C | Excellent | Suitable for full concentration range. | |
| Oxidizing Agents | |||||
| Hydrogen Peroxide (H₂O₂) | ≤30% | ≤60°C | Moderate | >30% concentration or >60°C accelerates aging. | |
| Ozone (O₃) | All | Any | Excellent | Exceptional ozone resistance (ideal for outdoor use). | |
| Sodium Hypochlorite (NaClO) | ≤15% | ≤25°C | Moderate | >15% concentration or high temperatures cause cracking. | |
O-RING Size Calculation
The selection of O-rings primarily depends on compression ratio because it directly impacts the sealing performance, durability.
Formula for Compression Ratio
The compression ratio () of an O-ring is calculated using the following equation:
C=(CS−Gd)/CS × 100%
Where:
= Cross-sectional diameter of the O-ring (mm or inches)
= Groove depth (mm or inches)
Acceptable Compression Ratio Guidelines
| Application Type | Recommended Compression Ratio | |
|---|---|---|
| Static Seals | 15% – 30% | |
| Dynamic Seals | 10% – 20% | |
| High-Pressure Seals | 20% – 30% |
O-Ring Lubrication
Surface coatings are applied to O-rings to enhance their performance in demanding applications. The primary purposes include:
Friction Reduction: Minimize assembly force.
Chemical Resistance: Protects against aggressive media (acids, solvents, fuels).
Coating Materials
| Coating Material | Key Properties | Color |
|---|---|---|
| PTFE (Polytetrafluoroethylene) | – Ultra-low friction (μ ≈ 0.05–0.1) – Chemical inertness – Temp range: -60°C to +260°C | Light white |
| Lubricate FP(PFPE based lubricating fluid) | – Low friction – Prevent the O-rings from twisting – Compatible with cleanness requirements – NO impact on the mechanical properties of the rubber | Transparent |
| Molybdenum Disulfide (MoS₂) | – Low friction – Anti-galling | Dark grey |
O-Ring Color
Different color can be chosen for easlier identification.
- Black
- Blue
- Purple
Typical Applications
- Automotive – Cooling System
- Automotive – HVAC System
- Automotive – Braking System
- Drink Water Industry
- Food Industry
Thanks to contact us to discuss your requirements regarding O-RINGs. We are ready to assist you with fast, reliable support.