The eDart Dual Valve Controller (DVC) is used to control two valves which act in parallel with a single 4-20mA signal from the control room. Typically, this could be two parallel internal dart valves or the external Dual eDART. The DVC intelligently splits the single 4-20mA signal into two signals. These signals are fed to each positioner of the valve pair. The DVC simplifies the control of dual valves as no special PLC modification need to be made in order to operate a dual valve configuration. To the PLC the two valves are then treated as one valve. The control loop can still be tuned using classic PID controllers. The DVC often leads to improved control as the two valves are prevented from interacting with each other.
- The DVC requires a 4 – 20 mA signal and 24 VDC power source. Optionally, a 240 VAC power can be used.
- The input signal is isolated from the power supply.
- The characteristic of the two valves and the desired characteristic of the combined unit can be programmed.
- The Master and Slave output can be reversed periodically if the application requires this to prevent sanding.
- The time between reversals and the time to complete a reversal is programmable to prevent any surges to the plant.
- The DVC will produce a calibration certificate, including serial number, and date for each calibration.
- One DVC can drive another DVC to control a third valve if required.
- The control algorithm is designed to prevent one valve operating close to the seat whilst the other valve is fully open.