Setting Relief Valves in Hydraulic Systems: A Practical Guide

In hydraulics, safety and reliability are everything. One wrong move can damage equipment, cause costly downtime, or put someone at risk. That’s why the relief valve, your system’s pressure safeguard, matters.

A relief valve protects your gear and your crew. It opens when pressure gets too high, letting fluid escape and preventing serious damage. Setting it right is not just a good habit, it’s essential.

Step 1: Know Your System

Before adjusting anything, you need to understand the system layout and how pressure is controlled.

Study the hydraulic schematic: This is your roadmap to the system. It shows where the relief valve is located, how the flow path works, and where to safely build system pressure.
Identify key components: Pump, valve bank, actuators, pressure gauges, test points.
Refer to manufacturer specs: Check the maximum working pressure for each component and confirm the recommended relief valve setting.

Never adjust a relief valve without first fully understanding the system and what the setting should be!

Step 2: Locate the Relief Valve

In most systems, the main relief valve is located in the valve bank (control valve) or in the main pressure line near the pump. However, the exact location varies – especially between open-centre and closed-centre systems.

Use the circuit diagram to correctly identify the relief valve. If unsure, seek guidance before continuing.

Step 3: Understand How to Load the System Safely

To test or adjust the relief valve, the system must reach maximum working pressure. This requires applying load in a controlled and safe way.

Use the schematic to determine how the system can be loaded.
Some systems may require actuating a specific function to build pressure (e.g., dead-heading a cylinder or operating a valve against load).
Follow a defined procedure for building pressure (as taught in your practical workshop sessions)

Never guess how to load the system – stuff it up and it could be expensive and/or dangerous!

Step 4: Adjust Gradually

Once the system is at normal operating temperature and you’ve confirmed the relief valve location:

Use the correct tool for the adjustment (usually a hex key or screwdriver).

Adjust the valve in small increments.
Clockwise usually increases pressure / Counterclockwise usually decreases pressure – check data sheets before adjusting.
Monitor the pressure gauge closely during adjustments.

Always stay within the manufacturer’s pressure limits.

If the pressure continues to climb without the relief valve opening, stop and recheck. The valve may be stuck, blocked, or adjusted too high.

Step 5: Monitor System Behaviour

As you adjust and operate the system:

Watch for unusual pressure spikes
Listen for strange noises (e.g., valve chatter or whine)
Look for fluid leaks or foaming

Any unexpected behaviour should be investigated before continuing. Relief valve issues can sometimes be caused by contamination or internal wear, not just incorrect settings.

Step 6: Test and Verify

Once your adjustment is made:

Safely build pressure using the method outlined in Step 3.
Confirm that the relief valve opens at the correct pressure setting.
Check that it reseats properly and doesn’t chatter or stick.

Record the test results for future reference or servicing.

Safety First – Always

Hydraulic systems operate under high force. Take appropriate precautions:

Wear the correct PPE: gloves, safety glasses, and steel-cap boots.
Always fully depressurise the system before making any changes.
Never exceed pressure ratings – you are responsible for keeping yourself and your gear safe.
Follow lock-out/tag-out procedures when working on pressurised systems.

APT Training Tip

Understanding system schematics and knowing how to safely load a hydraulic system are core parts of our practical relief valve training. In our hands-on courses, you’ll learn to:

Interpret hydraulic circuit diagrams
Identify and locate relief valves in various setups
Set and verify pressure correctly using real-world equipment
Troubleshoot valve issues, including contamination and failure to reseat

Do It Right, Every Time

A correctly set relief valve doesn’t just protect machines – it protects people. Taking the time to understand the system, follow proper procedures, and test thoroughly will help ensure your hydraulic system runs safely, reliably, and efficiently.

Ready to gain hands-on confidence with real systems?

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