There are also some installation or maintenance details to emphasize: (1) For the confirmation of the opening position, it needs to be determined according to the rotation angle of the butterfly valve; (2) During installation, the valve disc needs to stop at the "off" closed position; (3) If the electric butterfly valve is equipped with a bypass valve, the bypass valve shall be opened before opening; (4) The installation must be carried out in strict accordance with the factory instructions. If a heavy electric butterfly valve is encountered, a firm foundation needs to be set. 　　

Flash evaporation refers to the phenomenon that when the static pressure from the constriction section to the valve outlet decreases to equal to or lower than the saturated vapor pressure of the fluid at the valve inlet temperature after the incompressible fluid is throttled through the control valve, part of the liquid vaporizes to form gas-liquid two phases behind the valve. The flash evaporation makes the liquid flow no longer increase with the increase of pressure drop, resulting in blocked flow, Flash evaporation also causes gas-liquid two-phase flow. Gas and liquid flow through the valve core and downstream pipeline at the same time, resulting in erosion. It is characterized by the smooth and polished shape of the valve core. Cavitation refers to the phenomenon that when the fluid passes through the control valve, the static pressure at the constriction section decreases to equal to or lower than the saturated vapor pressure of the fluid at the valve inlet temperature, some liquid vaporizes to form bubbles, and then the static pressure returns to the saturated vapor pressure, and the bubble breaks back to the liquid phase. The whole process of bubble generation and breaking is called cavitation.