Bürkert looks at the improvements in design that have allowed an increasing number of processes to rely on this essential device.
Top tip 1 : Design principles - For applications involving ambient temperatures up to 250 degree C, it is important to ensure that the coils can withstand these conditions and so anodised enamelled copper wires may be used to ensure reliable operation.
Top tip 2 : Valve anatomy - Essentially solenoid valves are split between two designs, direct acting and pilot-operated.
Direct acting relies solely on the power of the magnetic coil to make or break the seal with the seat of the valve. In normally closed (NC) configurations, the coil is energised and the valve opens until the voltage is removed and the spring pressure closes the valve. The pressure and flow capabilities of these valves are determined by the power of the solenoid.
A pilot operated solenoid valve uses the pressure differential between the inlet and the outlet to assist the solenoid coil and spring in opening and closing the valve. This design concept can be applied to various styles of solenoid valve in order to accommodate a wide range of applications where higher pressures and flows are required.
Top tip 3 : Selection process - In the case of solenoid valve design, the general rule-of-thumb is: Plunger-type direct acting solenoid valves are best suited to neutral and clean fluids, while pivoted armature solenoid valves employ a media-separating membrane and are therefore suitable for controlling corrosive, contaminated or aggressive fluids.
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