It is possible for a supply unit on a PF3W Digital Flow Sensor Manifold to reach its end of life.  This may be due to some accident such as excessive external force, contamination, or electrical malfunction.  If this happens, it is possible to replace an individual supply unit for one lline without having to replace the entire manifold.  The supply unit may consist of a basic block, a flow adjustment or stop valve, or a combination.  Kits also include mounting screws and an O-ring seal.