Will the rear outlet pressure of a reducing valve change if the rear valve (butterfly valve, ball valve or switch valve) is closed during normal operation of a reducing vale?

For ZJY46H piston reducing valve made in Xiangtan Zhongji Power Station Auxiliaries Manufacturing Co.,Ltd, it will be closed automatically if the related valves behind it are closed during its normal operation. By analyzing the operating principle of ZJY46H piston reducing valve, you will find that its rear outlet pressure will rise slightly but will not exceed 20% of the outlet pressure specified in the standard after being closed. Therefore, for any reducing valve, to ensure a longer service life for it, do not use it as a switch valve.