The overflow valve is the key guarantee for the safe application of pressure pipeline and pressure vessel. In order to ensure the normal operation of the overflow valve and extend its service life, the safety valve in operation shall be regularly checked for leakage, jamming, spring corrosion and other abnormal phenomena. Pay attention to observe whether the adjusting screw sleeve and the locking nut of the adjusting ring set screw are loose. Take appropriate maintenance measures in time if problems are found. The safety valve shall also be removed regularly for comprehensive cleaning, inspection, regrinding and setting before reuse. The overflow valve installed outdoors shall take appropriate protective measures to prevent rain, fog, dust, rust and other dirt from invading the overflow valve and discharge pipeline. When the environment is lower than zero degree centigrade, necessary antifreeze measures shall be taken to ensure the reliability of overflow valve action. The excavator may encounter overflow valve failure during use. This article will explain the possible causes of overflow valve failure. For reference only.
1. If the damper of main valve body is blocked and the oil pressure cannot be transmitted to the upper chamber of main valve and the front chamber of pilot valve, the pilot valve will lose its regulating effect on the pressure of main valve. Since there is no oil pressure in the upper chamber of the main valve and the spring force is very small, the main valve becomes a direct overflow valve with very small spring force. When the pressure in the oil inlet chamber is very low, the main valve will open and overflow, and the system will not be able to form pressure. The reason why the pressure cannot reach the rated value is that the pressure regulating spring is deformed or selected incorrectly, the compression stroke of the pressure regulating spring is not enough, the internal leakage of the valve is too large, or the pilot valve is excessively worn.
2. If the damper is blocked and the oil pressure cannot be transmitted to the cone valve, the pilot valve will lose the regulating function of the branch and main valve pressure. After the damper is blocked, the cone valve will not open the overflow oil under any pressure. There is no oil flow in the valve, and the pressure in the upper and lower chambers of the main valve is always equal. Since the annular pressure bearing area at the upper end of the main valve element is greater than that at the lower end, the main valve is always closed without overflow, and the pressure of the main valve rises with the increase of load. When the actuator stops working, the system pressure will increase infinitely. In addition to these reasons, check whether the external control port is blocked and whether the cone valve is installed well.
