That understanding might bewhy ... were inventedBitter solenoid magnets

to replace a solenoid valve coil and to(passive) has been designedsolenoid valve operating magnet

These physical vibrationsoriginatingfrom the magnet / solenoid

to convert electrically operated solenoid valves in to hand - operated valves to enable service engineers to operate valves manually(passive) is designedSolenoid Valve Operating Magnet