Struggling to find the right O-ring for your high-pressure application? Choosing an O-ring incapable of handling your required pressure could lead to costly leaks or system failures.
Standard O-rings typically withstand pressures up to 1,500 psi (100 bar). Specially designed O-rings with backup rings can handle pressures exceeding 5,000 psi (345 bar).
The maximum pressure an O-ring can withstand depends on several factors, including material type, hardness, groove design, and whether backup rings are used. Let's explore these factors in depth.
What Is the PSI Rating of O-Ring?
Confused by PSI ratings and their significance for O-ring performance? An incorrect understanding might lead to choosing unsuitable seals.
PSI (pounds per square inch) rating indicates the maximum pressure an O-ring can safely handle without extruding or failing. Typical ratings range from 800 to 5,000+ psi based on material and support rings.
Typical PSI Ratings for Common O-ring Materials:
| O-ring Material | PSI Rating (without backup) | PSI Rating (with backup rings) |
|---|---|---|
| ✅ Nitrile (NBR) | 1,500 psi | 5,000 psi |
| ✅ EPDM | 1,500 psi | 3,500 psi |
| ✅ Viton (FKM) | 2,000 psi | 5,000 psi |
| ✅ Silicone | 800 psi | 2,500 psi |
| ✅ PTFE (Teflon) | 3,000 psi | 10,000 psi |
Understanding PSI ratings helps select the right O-ring material and setup for your specific requirements.
What is the Pressure Rating for the NBR 70 O-ring?
Not sure how much pressure your NBR 70 O-ring can handle? Selecting the wrong hardness can result in premature seal failure.
NBR 70 (70 Shore A nitrile) O-rings typically handle pressures up to approximately 1,500 psi (100 bar) without backup rings. Using backup rings can significantly increase this rating up to 5,000 psi (345 bar).
Pressure Ratings for NBR 70 O-rings1:
| Configuration | Max Pressure (Approx.) |
|---|---|
| ✅ NBR 70 (No backup) | 1,500 psi (100 bar) |
| ✅ NBR 70 + Backup ring | 5,000 psi (345 bar) |
For higher pressures, consider using NBR 90 (90 Shore A) with backup rings, which offer greater extrusion resistance.
Factors Influencing O-Ring Pressure Rating2
Unsure about the factors that impact an O-ring’s ability to withstand pressure? Identifying these elements can improve your seal selection.
Material type, hardness (durometer), groove design, use of backup rings, and operational conditions significantly affect O-ring pressure capabilities.
Key Factors Affecting O-ring Pressure Resistance:
| Factor | Impact on Pressure Rating |
|---|---|
| ✅ Material Type | High-strength elastomers (NBR, FKM, PTFE) handle higher pressures |
| ✅ Durometer (Hardness) | Harder O-rings (80-90 Shore A) resist extrusion better |
| ✅ Groove Design | Tight groove tolerances prevent extrusion, increasing pressure rating |
| ✅ Backup Rings | Prevent extrusion, greatly boosting pressure ratings |
| ✅ Operating Conditions | Temperature and fluid exposure affect pressure capacity |
How to Calculate O-ring Pressure?
Struggling to determine if your O-ring can handle specific pressures? Incorrect calculations could lead to unexpected seal failure.
O-ring pressure calculation involves assessing extrusion gaps, seal material, durometer, and backup ring usage.
Simplified Method to Estimate O-ring Pressure Capacity:
Identify Maximum Extrusion Gap
- Measure the clearance between mating surfaces in your assembly.
Choose O-ring Durometer and Material
- Higher durometer (80-90 Shore A) withstands greater pressures.
Check Extrusion Resistance (General Guidelines):
| Extrusion Gap (inch/mm) | Recommended Max Pressure (psi/bar) |
|---|---|
| ≤0.002 (0.05 mm) | up to 5,000 psi (345 bar) |
| 0.002–0.005 (0.05–0.13 mm) | up to 3,500 psi (240 bar) |
| 0.005–0.010 (0.13–0.25 mm) | up to 1,500 psi (100 bar) |
| >0.010 (0.25 mm) | ≤ 800 psi (55 bar) |
- Backup Rings
- Include backup rings for higher pressures to reduce extrusion and extend seal life.
By following these guidelines, you can accurately determine your O-ring’s safe pressure limits.
Using Backup Rings3 to Increase Pressure Ratings
Concerned your O-ring alone might not handle extreme pressures? Backup rings significantly increase pressure handling capabilities.
Backup rings, often made from PTFE or rigid plastics, prevent extrusion and drastically improve an O-ring’s resistance to high pressure.
Typical Pressure Improvement with Backup Rings:
| Setup | Max Pressure (approx.) |
|---|---|
| ✅ O-ring alone | ~1,500 psi (100 bar) |
| ✅ O-ring + 1 Backup Ring | 3,000–5,000 psi (207–345 bar) |
| ✅ O-ring + 2 Backup Rings | 5,000–10,000 psi (345–690 bar) |
Backup rings are essential for high-pressure scenarios, ensuring reliability and extended service life.
How to Select the Right O-ring for High Pressure?
Not sure how to pick the correct O-ring for your application? Proper selection ensures safe and reliable sealing under pressure.
When selecting high-pressure O-rings, consider material compatibility, durometer, groove dimensions, backup ring usage, and operating conditions.
Checklist for High-Pressure O-ring4 Selection:
✅ Confirm operating pressure requirements
✅ Choose suitable O-ring material and hardness
✅ Include backup rings if necessary
✅ Verify precise groove design and dimensions
✅ Consider fluid compatibility and temperature range
Careful selection guarantees optimal sealing performance.
Conclusion
O-rings can typically handle pressures up to 1,500 psi, with backup rings extending this capacity to over 5,000 psi. Understanding factors like PSI ratings, extrusion gaps, and backup rings ensures reliable and safe sealing performance.
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Explore this link to understand the pressure limits and applications of NBR 70 O-rings, ensuring optimal performance in your projects. ↩
This resource provides insights into the critical factors affecting O-ring pressure ratings, helping you make informed decisions for your sealing needs. ↩
Learn how backup rings enhance O-ring performance under pressure, ensuring reliability and longevity in high-stress applications. ↩
Learn the key factors in selecting high-pressure O-rings to ensure safe and effective sealing in demanding applications. ↩
