In standard solenoid valves, the solenoid requires the introduction of an electric current to produce a magnetic field. This magnetic field pulls the plunger away from the opening and allows the valve to open. With standard solenoid valves, they must continuously receive electrical power to keep the plunger in the open position, which makes them inefficient compared to magnetic solenoids. Magnetic latching solenoids have a small permanent magnet fitted on top of the valve. The introduction of the permanent magnet allows the valve to stay open even after the electrical power is turned off, offering more significant energy saving options as compared to standard solenoids.
To close latching solenoid, an electrical charge is applied to reverse the magnet’s polarity. This makes the magnetic latching solenoid valves useful in situations that require the valve to remain open for an extended period.
Some application areas for magnetic latching solenoids include medical equipment, security devices, automatic door closers, latching mechanisms, battery-powered equipment, among others.
The two main types of latching solenoids are Permanent Magnet and Residual Magnetism.
Permanent magnet latching solenoids make use of permanent magnets to generate attraction needed to open the valve. Pulsing short currents either increases or decreases the electromagnetic flux depending on the current’s polarity.
Latching solenoids that use residual magnetism function similarly to permanent magnet latching solenoids. The significant difference, however, is that residual magnetism solenoids do not use permanent magnets.
They make use of the residual magnetism enhanced through specific design implementations. Latching solenoids enable latching force without the need for permanent magnets or constant power. Closing the valve is done through the application of an electric pulse of a lower current with a different polarity than that used to open it.
Unlike permanent magnet latching solenoids, which can be latched manually, residual magnetism latching solenoids require an application of electrical current to reset it after de-latching.
To ensure the high and constant efficiency of your magnetic latching solenoid functionality, it is essential to note that:
Foreign matter can find its way into the core tubes. When the foreign matter accumulates, it can interfere with the solenoids desired operation. It is also important that you apply the appropriate voltage to the valves; too little might lead to ‘chattering,’ will prevent the valve from opening or closing and could cause it to wear much faster. Applying too much voltage, on the other hand, will produce too much heat, which will lead the solenoid to wear out prematurely.
Keep an eye on the moisture also. If moisture seeps into the solenoid’s interior, it will result in the coil failing which will impede the opening or closing of the valve.
Check out some of our magnetic latching solenoids suitable for various application areas such as:
If you are purchasing a solenoid valve for your unique application, talk to Johnson Electric’s experienced solenoid distributors and manufacturer reps for more information on the solenoids available.
Having the right solenoid fitted into your application ensures system functionality and efficiency, and lowers the need for regular maintenance.