What is the difference between working pressure and allowable differential pressure of HYDAC filter elements?

Working pressure and allowable differential pressure are two core parameters of HYDAC filter elements. They differ completely in definition, function and control criteria, and both are indispensable for model selection and daily maintenance.

Working pressure refers to the overall pressure of the hydraulic fluid inside the pipeline where the filter operates continuously. It indicates the pressure resistance limit of the entire structure including the filter housing, end caps, seals and support frames, and determines which circuit the filter can be installed in. The rated working pressure of HYDAC low-pressure glass fiber filter elements is generally 25 bar for low-pressure lines such as return lines and suction lines, while high-pressure versions can reach 210 bar for main pressure oil circuits. Long-term operation exceeding the rated working pressure will lead to housing deformation, seal leakage and end cap debonding, resulting in equipment failures.

Allowable differential pressure specifically means the pressure difference between the filter inlet and outlet, generated by flow resistance when oil passes through the filter media. It is a key indicator to judge the clogging level of the filter. A new filter has an extremely low initial differential pressure, which rises gradually as contaminants are trapped. The maximum allowable differential pressure of standard HYDAC filters ranges from 0.2 to 0.35 MPa. When this value is reached, the differential pressure alarm will be activated and the built-in bypass valve will open to maintain uninterrupted oil flow.