Solenoid valve

A solenoid valve is a valve which is actuated by an electromagnet. Depending on the design of these valves can switch very quickly. Solenoid valves with position detection can be operated as servo valves. The trend in the industry is toward small voltages ( 24 V DC) and small performances by feedforward control of the valves.

Types of control

According to its operating valves can be divided into the categories listed below.

Direct acting valves

Valves of this type use a drive with electromagnet; the drive is directly connected to the sealing element, the valve piston. When electromagnet is switched off, a compression spring keeps the valve closed by pressing the valve piston against the valve seat. The direction of flow of the medium through the valve is intended determined that the valve is closed the building up between the inlet and outlet of the valve differential pressure the valve piston also presses against the valve seat. To open the valve, the piston must be raised solely by the electromagnetic actuator from the valve seat; the drive must therefore work against the pressure spring and against the present at the valve piston differential pressure. The minimum required power of the electromagnetic drive to open the valve depends primarily on the spring force, the valve seat size and the maximum differential pressure with the valve closed.

Pilot operated valves

Valves of this type need to open and close, a pressure difference in the operating pressure. The min. pressure necessary for this is stated as the minimum pressure in the technical data sheet. The drive met here only a pilot function, through which the main sealing element ( diaphragm or piston) is relieved. The medium pressure, or the pressure difference existing lifts the main seal. In this control high pressures can be controlled with large diameters with small magnets. Example: those pilot-operated valves are used in heating spas for application to temporarily switch the hot water flow from the heating circuit to a hot water boiler to heat this, eg Junkers in older condensing boiler CL 100

Force pilot operated valves

Valves of this type are a combination of pilot-operated and direct acting valves. Switch from 0 bar and are also used where direct-operated valves are used. However, they are delivered via the application area also with smaller magnets for higher pressures and larger diameters. The drive opens a pilot hole and then lifts directly, or supported by the differential pressure between inlet and outlet, the sealing element from the head office from. The special feature of this control is that the drive can not support open and close the valve by the pressure difference between inlet and outlet.

Pressure controlled valves

Valves of this type are controlled by an external pilot valve inserted. This allows them to clean control medium high temperatures, high pressures, contaminated media, aggressive working capital, etc. controlled.

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