Walchem Corp., of Holliston, Mass., introduces the WDP Series Dual Input pH/ORP controllers. These versatile controllers accept two electrode signals, in any combination of pH and ORP, and are offered in a convenient pre-wired NEMA 4X wall-mount package that can be installed in minutes. The dual input models are more cost effective than two single input models. There are four control outputs, available as on/off control relays, or as pulse proportional outputs, to directly drive electronic metering pumps.