Abstract: A valve mechanism is used in combination with a fluid treatment device of the type having a tank defining a treatment bed, particulate treatment material contained within the treatment bed, and a central distribution tube mounted in the bed and terminating in a plurality of distributors which provide fluid communication between the bed and the distribution tube. The valve mechanism consists of a plurality of ball valves, each connected to a different one of the distributors and having unidirectional flow restriction assemblies such that fluid flow in a first direction from the bed to the distributor tube is relatively unrestricted, and fluid flow in a second direction from the distribution tube to the treatment bed is relatively restricted.

Abstract: A mixed bed deionizer unit which provides in situ regeneration through the use of two compact multi-valve assemblies and an intermediate manifold which are automatically controlled to supply backwash water, chemical draw for cleansing both cation and anion resins simultaneously and rinsing water in a sequentially controlled manner. An internal water and chemical distribution system in the mixed bed tank is provided which has both input distribution and output drainage capabilities.