Abstract: A valve which may be interposed in a pipeline system in such a manner for injecting or launching of spheres into the interior of the pipeline individually and in sequence, and which may be alternatively interposed in the system for receiving previously injected spheres from the interior of the pipeline. The valve comprises a launch mechanism actuated by gravity and which has a single moving part, and in the receiving operation a blocking bar is provided for precluding incoming spheres from inadvertently or accidentally lodging within the valve body.