The filter element can be considered to have a gradually reduced flow section as it intercepts solid particles of pollutants during operation.The flow through the filter element is the flow in the pipeline where the filter is installed, and the filter element does not cause a change in flow. As the flow section areahereinafter referred to as the flow area) of the filter element decreases due to the interception of solid particles of pollutants, the pressure loss generated by the filter element gradually increases and when it reaches a certain value, the filter with an alarm device will send out an alarm signal to notify the user to replace the filter element in time.If the element is not replaced in time, the flow area of the filter element will further decrease with the interception of pollutants, and the pressure loss will further increase. In addition to alarm signal, the bypass valve of the filter with a bypass valve will also open, and part of the oil will flow out directly from the bypass valve without being filtered by the filter. Even the pollutants that have been intercepted by the filter element will also be directly carried to the downstream of the filter element by the oil through the bypass valve, which willate the previous filtration interception and cause great damage to the hydraulic system components.But even if part of the oil flows away from the bypass valve, there is still oil flowing the filter element, the filter element continues to intercept pollutants, its flow area further decreases, and the pressure loss further increases, the bypass valve increases the opening area. In this, the flow area of the filter element continues to decrease, the pressure loss continues to increase, when it reaches a certain value (this value must have exceeded the normal working pressure value the filter element or filter), when it exceeds the pressure bearing capacity of the filter element or even the filter, it will cause damage to the filter element and the filter housing.The function of the bypass valve is mainly to provide a short-time bypass function for the oil when it is not possible to stop the machine for replacement of the filter element Therefore, when the filter element is clogged, it is necessary to replace the filter element in time, and it is not allowed to replace the filter element normally because of the protection the bypass valve.In order to provide the most reliable protection for the hydraulic system components, we recommend that the filter should not be equipped with a bypass valve as much as.