How to Adjust the Pressure of a Pressure Relief Valve?
2 Answers
Pressure relief valve adjustment method is as follows: 1. Open the angle needle valve; 2. Loosen the positioning nut and turn the top adjusting screw counterclockwise; 3. Open the front-end water inlet (gate or butterfly) valve; 4. According to the pressure gauge, tighten the top adjusting screw clockwise as required, and start the water pump to verify the high pressure; 5. Adjust the angle needle valve to stabilize the pressure as much as possible, turn off the water pump to verify the fully closed pressure, and lock the positioning nut. The pressure relief valve, also known as the safety valve, automatically opens and closes according to the working pressure of the system. It is generally installed on the equipment or pipeline of a closed system to protect the system's safety. When the pressure reaches the upper safety limit, the pressure relief valve automatically opens to reduce the pressure and ensure safety.
To adjust the relief valve pressure, first locate the adjustment screw on the valve body, usually a hex socket screw with a locknut. When I work on these in the garage, I prepare a professional pressure gauge connected to the relief valve outlet and slowly turn the adjustment screw. Turning it clockwise increases the pressure, while turning it counterclockwise decreases the pressure—just a small turn each time is enough. After adjustment, tighten the locknut to prevent loosening. Note: Ensure the system is depressurized before making adjustments—safety first. The location of the relief valve varies significantly between different car models. Japanese cars often have it near the turbo, while German cars usually integrate it into the intake pipe. Setting it too high may trigger the fault light or even cause a burst pipe, while setting it too low can affect power response. It's best to test-drive after adjustment to check if the pressure relief is smooth during hard acceleration.
