the inertia ball comes to rest at the original horizontal position shown in fig8 an additional safety is provided when the external magnet 32 is moved upward along a controlled path as previously described should the flapper 34 fail to rotate into the open position thus indicating that the fluid pressure differential is greater than the force produced by the magnet 32 this would indicate that the fluid should not be turned on for safety reasons a modified embodiment of the present invention will now be described with reference to fig9 and 10 similar to the previous embodiment the valve consists of a closed housing 120 shown without the top cover and having an inlet 122 and an outlet 124 a flapper 134 of another version is made in one piece thus eliminating the lever as shown in fig9 the flow of fluid through the valve is shown by flow arrows 118 an inertia ball 128 is shown in fig9 depicting the movement of the inertia ball 128 from a biased recess 146 to the off position the operation of the valve is similar to the above embodiment except the flapper 134 is held in the off position by the inertia ball 128 being forced by the action of gravity and a magnetic force exerted by an external magnet 132 against a ball stop 144 and the flapper 134 more specifically the operation of the valve shuts off the flow of fluid.