Air, water solenoid valve for the second diaphragm-type pilot-operated solenoid valve, the structure of the main valve from the main valve and composition. According to the different state when the power is off, can be divided into normally closed solenoid valve and normally open solenoid valve. Normally closed solenoid valve, standing, the activities of the core seal the Deputy valve port, valve cavity pressure balance, deputy valve, the main valve port closed. When the coil is electrified, the movable iron core is sucked up by the electromagnetic force, and the auxiliary valve is opened. The medium in the main valve cavity leaks out of the pilot valve port, so that the pressure difference between the main valve diaphragm and the diaphragm is rapidly raised. The main valve port Open, the valve was the passage of state. When the coil is de-energized, the magnetic field disappears and the movable core is reset. The secondary valve port is closed, and the pressure in the upper chamber of the secondary valve diaphragm rises. The main valve diaphragm is pressed against the valve seat and the valve is closed again. Normally open solenoid valve, when the coil is energized, the magnetic field force is generated. The armature moves downward under the action of magnetic force to push the valve cup of the secondary valve down and the secondary valve to close. As the pressure difference between the upper and lower sides of the main valve tends to be equal, By the spring force and self-weight pressure to the sealing surface, the valve closed. When the coil power, the magnetic force is zero, the armature and vice valve cup due to the role of the spring rise, the deputy valve open, the main valve diaphragm medium flow through the deputy valve, the pressure drops, when the pressure drops to a certain value, The role of the main valve from the pressure up and down up, the main valve open, air, water solenoid valve open. More keyword search: Solenoid valve