End Armaturen Solenoid valves Ukraine

In this control type the plunger is connected directly to the disc which either opens or closes the orifice. In the case of power ON or OFF (energized or de-energized coil) the coil supplies the power required to lift or lower the valve disc. As such the fluid pressure and flow rate determine correct operation. The solenoid valve operates at pressures ranging from zero to the top value in the chart. This type of control is typically used for smaller valves or on larger valves with lower working pressures. (e.g., gas valves)

Servo-assisted valves require a pressure difference for opening and closing the main shut-off element. This pressure difference is shown as minimum media pressure in the technical specification. These valves use a pilot nozzle driven by the coil, and a diaphragm to shut off the main valve orifice. Correct operation relies on fluid pressure. With the coil energized the plunger opens the pilot nozzle to release the pressure across the diaphragm. The resulting difference in pressure lifts the diaphragm free of the valve passage. With the coil de-energized the pilot nozzle shuts and the pressure passes through a so-called „equalisation“ hole, and is restored across the diaphragm, causing the valve to shut. This system of operation requires a difference between inlet and outlet pressures of the solenoid valve, equivalent to the force needed to lift the diaphragm or to hold it against the main valve orifice. The efficiency of the valve seat seal is dependant on the cross section of the seat, the pressure difference between inlet and outlet port and the pre-load force of the main valve spring. Servo-assisted valves, used as actuating elements, are highly suited for operating larger valves under higher working pressures.

“This type of valve does not require any pressure difference to open or close the main shut-off element. As per the technical specification they are suitable from zero bar upwards. To operate the valve the plunger first opens a pilot hole, the ensuing pressure lifts the diaphragm, this action is further reinforced by the opening stroke of the plunger. The combination of direct action (plunger) and indirect action (diaphragm) ensures full passage even at low pressures. Operation and seal seating remain stable even at zero pressure. This type of valve is suitable for operating larger valves at high pressures. The actuators are comparatively small in relation to direct-acting valves. The actuator stroke must be at least equal to the valve lift. The force must be sufficient to open the pilot bore and the main shut-off element against the spring force.