Walchem”sWDP400 Series dual-input pH/ORPcontrollers are designed for industrial, commercial and municipal watertreatmentapplications. The controllers accept two electrode signals, inany combination of pH and ORP, and are offered in a pre-wired NEMA 4Xwall mount package. The dual -input model reduces space requirementsand ismore cost effective than two single input models. Integrated datalogging is available to validate system performance.  A USB stickcan be used to extract data and event logs that includeelectrode measurements, temperature, accumulated chemical feed andrelay activation times. There are fourcontrol outputs, available as on/off control relays or as pulseproportional outputs to directly drive electronic metering pumps. Eachcontrol output can be assigned to either electrode, and relays can beeither a high or low setpoint, high or low alarm, in-range alarm, out-of-range alarm or probe wash. One or two optionalisolated 4-20mA outputs are available, which can be assigned to eitherelectrode input, to correspond to the pH, ORP or temperature. All controllers arecompatible with the WEL Series pH/ORP electrodes, which offer adifferential measurement technique that is immune toany possible ground-loop problems. Electrode troubleshooting is simplified through self-diagnostics. All models meet UL,CSA and CE standards for safety and performance, providing reliableoperation in harsh industrial environments subject to electrical orradio frequency noise interference.