Valve – a device for controlling the passage of fluid through a pipe or duct. They can be automated or manual. Designed for general applications or critical applications. Built for rugged and harsh environments or for general non-industrial use. The automation of a valve not only refers it’s actuation, but also includes positioning, feedback, and health diagnostics. Actuation can be accomplished through a number of means. You have manual actuation. (Whether a hand valve or a wheel) There is pneumatic operation, typically using air to open and close a valve. There is electric actuation, typically used when there is not a reliable source of air. There is hydraulic actuation used in niche applications. (subsea, pipeline, and the like…) Valve positioners compare a control signal to a valve actuator's position and move the actuator accordingly. They are used with both linear valves and rotary valves. Valve positioners are used when the 0.2 to 1 bar pressure in the diaphragm chamber is not able to cope with friction and high differential pressures. There is a variety of valve positioning, electro-pnuematic (I/P), pneumatic, digital, and electronic. Feedback is the communication of where the valve actually is in comparison to where the input says it should be. Feedback devices can come in the form of a positioner, HART signal, Profibus or Fieldbus signal, or a separate 4-20ma feedback transmitter. Lastly, Diagnostics. Diagnostics are typically sent via HART, Profibus, or Fieldbus signals. This data is collected in an Asset Management software, like Honeywell’s FDM (Field Device Manager) or Fishers AMS system. This HART data can be communicated via twisted pair, or wirelessly (either WirelessHART or ISA100) Relevant represents a number of valve manufacturers, Everything from globe style control valves, V-Ball control valves, Segmented control valves, Butterfly valves, ball valves, knife edge valve, gate valves and needle valves.