[Proficient in hydraulics] - Filter: limited protection of the bypass valve

The filter element of the filter is considered to be a flow cross section that gradually becomes smaller as the solid particle contaminant is intercepted during use.

The flow through the filter element is the flow in the line where the filter is installed, and the filter element does not change the flow rate. When the area of the flow cross section of the filter element (hereinafter referred to as the flow area) becomes smaller as the interception of solid particle contaminants becomes smaller, the pressure loss generated by the filter element gradually increases, and when a certain value is reached, a transmitter is provided. The filter is sent by a transmitter alarm to inform the user to replace the filter element in time.

If the filter element is not replaced in time, the filter element flow area will further decrease with the contaminant interception, and the pressure loss will further increase. In addition to the alarm of the transmitter, the bypass valve of the filter with the bypass valve will also open. Part of the oil flows directly from the bypass valve without filtration. Even contaminants that have been intercepted by the filter element are directly carried by the oil through the bypass valve to the downstream of the filter element, causing the previous filter interception to fail, causing great damage to the hydraulic system components.

However, even if part of the oil flows away from the bypass valve, there is still oil flowing through the filter element, the filter element continues to intercept the pollutants, the flow area is further reduced, the pressure loss is further increased, and the bypass valve increases the opening area. In this process, the flow area of the filter element continues to decrease, and the pressure loss continues to increase. When a certain value is reached (this value must have exceeded the normal use pressure value of the filter element or filter), the ultra-filter or even the filter Damage to the filter element and filter housing can occur when the pressure is applied.

The function of the bypass valve is to provide a short-term oil bypass when the filter element cannot be stopped at any time (or at the expense of the filter effect of the filter element). Therefore, when the filter element is clogged, the filter element must be replaced in time. The filter element cannot be replaced normally because of the protection of the bypass valve.

In order to provide the most reliable protection for hydraulic system components, we recommend that the filter be as unselected as possible with a bypass valve.