Hydraulic Cylinder Pressure Test Explained: How to Conduct a Cylinder Test Procedure

The cylinder pressure test, designed to test the integrity of the piston seal and welds in hydraulic cylinders, pressurizes the cylinder during operation. Once the pressure has been applied, the cylinder is inspected for signs of leakage past the seal or welded parts. This process also performs a  “end-of-stroke bypass test”, and is a good indicator of the function of the hydraulic cylinder and whether a hydraulic cylinders repair is needed or has been completed correctly.

While this is a commonly used cylinder test procedure, the end-of-stroke bypass test doesn’t come without its limitations. Typically this test won’t reveal ballooning, which is better found with a piston-seal bypass test. Yet, still, it remains one of the best ways to ensure the success of your hydraulic cylinders.

To better understand the process of pressure testing a cylinder, we are breaking down more about the testing process and procedures to ensure a well-running system.

What Is the Hydraulic Cylinder Pressure Test Stand?

A hydraulic cylinder test stand is an apparatus that allows for operation of the cylinders under high pressure. This provides indications about  the conditions within the cylinder while it is tested, reporting the results throughout the process.

The Hydraulic Cylinder Pressure Test Procedure

The hydraulic cylinder test procedure includes several steps. Let’s break it down.

1. Start by securing the cylinder. Service ports should be up once secured.
2. Fill each side of the cylinder with hydraulic fluid through the service ports.
3. Connect the ball valves, gauges, relief valve, and directional control valve.
4. Leaving the ball valves open, use the directional control valve to stroke the cylinder multiple times, removing all remaining air from either side of the cylinder. Be sure not to ‘diesel’ the cylinder during this process.  
5. Put the piston rod in a mid-stroke position and close the ball valve.
6. Leaving the relief valve backed out, direct the flow to the rod side of the cylinder.
7. Increase the setting of the relief valve. Continue increasing until the rated pressure is seen on the gauge.
8. Close the ball valve and center the directional control valve.
9. Record the pressure readings on the two gauges. Continue monitoring the change over time.

In the case the differential pressure through the piston isn’t maintained during this monitoring process, it signals that there's a problem with either the piston seal or the tube.

During this process, the ball valve shouldn’t be closed when the flow is directed to the piston side of the cylinder. This could lead to cylinder failure or personal injury. To avoid this, wear personal protective equipment for your safety.

Why Should Hydraulic Cylinders Be Tested?

There are several reasons why a hydraulic cylinder tester is beneficial. The benefits of a cylinder pressure test include:

• Understanding the action of a hydraulic cylinder. The ability to hold pressure is essential to this action, and an inability to hold pressure is a signal of failing conditions in seals or even the cylinder housing.
• An inspection of the cylinder’s ability to hold pressure is a final signal of the cylinder’s reliability. Other elements of the cylinder can be inspected over time and during a repair process, but this test will ensure its quality.
• It will help identify internal sealing issues. While external leaking can be quite obvious, internal seals ensure no hydraulic fluid is moving around internally.
• Without testing and identifying internal and externally leaking seals, you will experience hydraulic fluid loss, loss of power, degradation, performance issue, and excessive energy consumption.
• Since replacing a hydraulic cylinder on heavier recruitment is cumbersome, ensuring it is truly repaired and carefully tested will ensure the long-term success of the cylinder, avoiding this time-consuming process of replacing it.

Conclusion

With an understanding of the benefits of the cylinder pressure test, as well as knowledge of the hydraulic cylinder test procedure, it’s time to check if your cylinders are operating as they should! For assistance from a trusted hydraulic cylinder repair company, Cylinders, Inc. can assist with all cylinder testing and repairs to ensure well-functioning cylinders support all of your machinery.

For assistance with your hydraulic cylinder maintenance and repair, contact us today.