How to test rod seal performance in the lab? | Insights by Polypac

Introduction

Rod seals are integral components in hydraulic and pneumatic systems, serving to prevent fluid leakage and contamination. Ensuring their optimal performance through rigorous laboratory testing is crucial for system efficiency and longevity. This guide outlines key laboratory methods for evaluating rod seal performance, including leakage testing, endurance testing, material compatibility assessment, and environmental testing.

1. Leakage Testing

Leakage testing is fundamental in assessing the sealing effectiveness of rod seals. Common methods include:

• Pressure Leakage Test: The seal is subjected to the system's operating pressure, and the pressure is monitored over a specified period. A significant pressure drop indicates leakage. For instance, testing a seal at 1000 psi and observing a pressure drop of more than 50 psi within 30 minutes suggests potential issues.
• Bubble Test: The seal is immersed in a liquid, typically water with added soap, and pressurized. The formation of bubbles at the leakage point visually confirms the presence of leaks. This method is effective for detecting obvious leaks but may be less precise for minor ones.

2. Endurance Testing

Endurance testing evaluates the durability and longevity of rod seals under continuous operational conditions. This involves:

• Simulated Cycles: The seal undergoes repeated cycles of pressure, temperature variations, and dynamic movements to mimic real-world operating conditions. This process helps identify potential weaknesses and assess the seal's performance over time.
• Friction Measurement: Monitoring the frictional forces during these cycles provides insights into the seal's wear characteristics and its impact on system efficiency. Excessive friction can lead to increased wear and reduced performance.

3. Material Compatibility Testing

Assessing the compatibility of seal materials with the operating fluids is essential to prevent degradation and ensure longevity. Methods include:

• Immersion Testing: Seal samples are immersed in the operating fluid for a specified duration, and changes in size, hardness, or appearance are monitored. Significant alterations may indicate material incompatibility, leading to premature seal failure.
• Compression Set Testing: The seal is compressed to a specific percentage of its original thickness and maintained for a set period. After decompression, the seal's ability to return to its original shape is evaluated. A high compression set percentage suggests reduced sealing effectiveness over time.

4. Environmental Testing

Environmental testing examines the seal's performance under various external conditions, such as temperature fluctuations, humidity, and exposure to contaminants. This includes:

• Temperature Cycling: The seal is subjected to alternating high and low temperatures to assess its ability to maintain sealing integrity across a range of environmental conditions.
• Contaminant Exposure: The seal is exposed to dust, dirt, or other contaminants to evaluate its effectiveness in preventing ingress and maintaining system cleanliness.

Conclusion: The Advantages of Polypac

Polypac offers a comprehensive suite of testing services tailored to rod seals, ensuring their performance and reliability in various applications. Their state-of-the-art facilities and adherence to industry standards provide valuable insights into seal behavior under diverse conditions, aiding in the development of high-quality sealing solutions.

References

• DMS Seals Technology Co., Limited — October 2025
• Jinbond Seal — November 2025
• Machine Design — November 2025
• Kastaş Test Center — October 2025
• MDPI — November 2025
• FlexPak — November 2025
• Mobile Hydraulic Tips — November 2025
• Testing Lab — October 2025
• Trelleborg — August 2025
• Prewel Labs — November 2025