Selector valves are valves used to divert a fluid or gas flow between two or more points rather than simply closing it off or allowing it to pass. There are a considerable number of different types of selector valves available with many industries or specific applications utilizing custom designed variants. Most, however, fall into a couple of basic categories, such as rotating spindle, piston, or dual-position ball type valves. In terms of their construction and the materials used, selector valves also fall into groups depending on the specific demands of the relevant application for which they are used. Although they do differ in layout and function, selector types more often than not share many of these specifics with conventional flow valves used in like applications.
Valves are universally used to control the flow of fluids and gases. They may be of a relatively simple on/off design used to allow or stop the flow, or may be used to regulate the amount of flow in a system. One particular family of valves is used to divert the flow of fluid or gas from their sources to one or more specific destinations. These selector valves are used where the down-stream or consumer demands of the system require the flow to be directed to different parts of the system when required. A simple Y-shaped type garden hose manifold is a good example of this type of valve.
Selector valves are commonly found in a wide range of industries ranging from complex hydraulic systems to simple domestic irrigation set-ups, and are available in a corresponding range of sizes, configurations, and capacities. Most, however, operate according to one of a small group of common designs. High-pressure selector valves are typically rotary spindle, piston, or multi-position ball types of a close-tolerance, high-strength design. Lower pressure valves destined for use with non-hazardous fluids such as irrigation systems will often be of a multiple position spindle or ball design of less robust construction.
Rotary spindle and ball selector valves operate along similar lines and feature a rotating, close-fitting central arbor or ball located within a casing or chamber. The spindle or ball has a fluid flow aperture passing through it which forms the fluid or gas flow path. Two or more corresponding exit ports are included in the casing, which line up linearly with this aperture. When the spindle or ball is turned, the flow path will alternately line up with either of the ports allowing the operator to choose which exit is used. These designs are available in both high and low pressure types.
Piston selector valves are typically only used in high-pressure applications. These valves feature a central rod equipped with one or more piston heads of a larger diameter along its length. The piston travels within a close fitting tube punctuated with exit ports which are alternately blocked or opened as the piston moves along its length. The piston position is operator-chosen and the fluid flows within the tube passing through whichever exit port is open. These valves are most commonly encountered in high-demand hydraulic systems.