I'm doing some drawings on a cooling system, which includes a couple of so called "magnet valves". What excactly is a magnet valve, and does it actually have anything to do with the normal type of magnets?
I believe it to be as per a normal solenoid valve, but with a permanent magnet so that when power cannot be supplied (in an emergency, for instance) the valve can still actuate to an off position. They're used in gas cookers as safety devices, I believe.
So do you physically move the magnet into position, or is the valve held against it by a stronger electromagnet, or what? If the latter, a spring would make more sense. If the former, why not just a lever?