Walchem”s WDP400 Series dual-input pH/ORP controllers are designed for industrial, commercial and municipal water treatment applications. The controllers accept two electrode signals, in any combination of pH and ORP, and are offered in a pre-wired NEMA 4X wall mount package. The dual -input model reduces space requirements and is more cost effective than two single input models. Integrated data logging is available to validate system performance. A USB stick can be used to extract data and event logs that include electrode measurements, temperature, accumulated chemical feed and relay activation times. There are four control outputs, available as on/off control relays or as pulse proportional outputs to directly drive electronic metering pumps. Each control output can be assigned to either electrode, and relays can be either a high or low setpoint, high or low alarm, in-range alarm, out-of-range alarm or probe wash. One or two optional isolated 4-20mA outputs are available, which can be assigned to either electrode input, to correspond to the pH, ORP or temperature. All controllers are compatible with the WEL Series pH/ORP electrodes, which offer a differential measurement technique that is immune to any possible ground-loop problems. Electrode troubleshooting is simplified through self-diagnostics. All models meet UL, CSA and CE standards for safety and performance, providing reliable operation in harsh industrial environments subject to electrical or radio frequency noise interference.