Abstract: A location detecting apparatus for use with a fluid conducting conduit in which a movable member moves includes an internally mounted magnet attached to the movable member and an external portion attached to the conduit for magnetically interacting with the internal magnet when the movable member is moved to a predetermined location. In the preferred embodiment there are two magnets, one extending from each end of the movable member. In this embodiment, the external portion includes two similar assemblies, each attached to a respective end of the conduit and each including suitable magnetically responsive switches, a reducing flange attached to the conduit, a manifold pipe extending through the reducing flange, and a clamping mechanism for releasably attaching the switches to the manifold pipe.