Sensorex has expanded its SD7000 family of Differential pH/ORP Sensors, adding four new models to suit a wider range of online process monitoring applications. The three-electrode differential sensor design results in less maintenance for operators, minimized downtime, longer sensor life and overall greater reliability. Process pH or ORP is measured differentially with process and protected inner reference electrodes, compared to a third ground electrode. The inner reference electrode is surrounded by a known concentrated pH 7 buffer that resists process contamination, maintaining its pH level with minimal dilution effects. A double junction salt bridge further guards against contamination.