Principle: It is a combination of direct-acting and pilot-operated principle. When there is no pressure difference between the inlet and the outlet, after the power is applied, the electromagnetic force directly lifts the pilot small valve and the main valve closing part in turn, and the valve opens. When the inlet and outlet reach the starting pressure difference, after the power is turned on, the electromagnetic force pilots the small valve. The pressure in the lower chamber of the main valve rises and the pressure in the upper chamber decreases, so the main valve is pushed upwards by the pressure difference. Force or media pressure pushes the closing piece and moves down to close the valve.
Features: It can operate at zero pressure difference, vacuum, high pressure, but the power is large, and it must be installed horizontally.