Once the moisture content of a seed sample has been determined, the appropriate amount of water needs to be added via a Phidget. These are the hardware devices that are being considered for the job of controlling the flow of water into the process.
- The Valve Shop has an excellent overview of the different types of valves available on the market.
- Phidget one servo motor controller. ($32)
- Solenoid valve, basically a high-end version of the irrigation valves used for the biodiesel processor. Would need a relay or some other means of driving, current draw may be too much for Phidget relay kit. Available from many different locations in many different configurations. ($70-$120)
- Electronically controlled proportioning valves are an expensive but perhaps more precise alternative that also appear to need a custom driving circuit. ($300)
- Belimo Pressure Independent Characterized Control Valves (PICCV) eliminate the need for calibration of the flow control apparatus, but at a steep cost. ($800-$1600)
- Aalborg SMV stepping motor valve's have precise stepper-motor control. ($550-$850)
- Pressure regulator to control the outlet pressure. Perhaps a pressure regulator set to a low (20PSI?) value will mitigate the pressure calibration issue. ($75)
- Flow regulator to control the flow, specified in gallons per minute. ($30)
- Pulse emitting water meter to determine the current flow rate, adjust flow control on the fly. ($185)