The hardness of O-ring rubber seals is indeed closely related to the pressure they can withstand. Generally, the higher the hardness of the O-ring, the greater the pressure it can handle.
Relationship Between Hardness and Pressure:
The higher the hardness, the greater the pressure-bearing capacity of the O-ring, making it suitable for high-pressure applications. However, the hardness should not be too high, as it may affect sealing performance and elasticity.
Some factors in below need also be taken into consideration when design the O-Ring:
- Application Environment: In addition to working pressure, working temperature and the type of medium are also important considerations for selecting hardness. For instance, in high-temperature environments, the hardness of the material may decrease. So a higher hardness material needs to be chosen to resist thermal degradation.
- Impact of Surface Quality: The smoothness of the groove and the roughness of the contact surface are crucial for the sealing performance of the O-ring. Smooth grooves and contact surfaces help improve sealing effectiveness, reduce wear, and extend the lifespan of the O-ring.
- Requirements for Rotary Motion: In rotary motion applications, the working pressure of the O-ring generally should not exceed 0.4 MPa. For such applications, the hardness is typically selected to be (70±5) Shore A. It ensures adequate sealing while minimizing friction and wear. If the working pressure exceeds 0.4 MPa, a special sealing device design is needed based on the specific circumstances. Such as adding a support ring or using other types of seals to enhance sealing reliability need to be considered.
- Add Back up rings：By providing additional support, they help maintain the shape and functionality of the O-ring.Back up rings are typically made from PTFE which have good wear resistance and can withstand high pressure and friction.
Here is the table indicating the relationship between FKM O-RING hardness and O ring working pressure. It could support for choose the right O RING handness with different working pressure.
| Hardness (Shore A) | Recommended Working Pressure (MPa) | Suitable Applications |
| 60 | ≤ 10 | Low-pressure sealing, chemical media |
| 70 | ≤ 15 | Medium pressure, automotive and industrial applications |
| 80 | ≤ 20 | Higher pressure, suitable for various environments |
| 90 | ≤ 25 | High-pressure applications, especially in the oil and gas industry |
| 95 | ≤ 30 | Extremely high pressure, oil&gas and other high-demand scenarios |
Please contact us, OBT Rubber Seal, for better understanding your technical requirement and our proposal.
