Emerson Electric Co. 1181PH Two-Wire pH Transmitter

Emerson's Rosemount 1181PH Two-Wire pH Transmitter is a loop-powered instrument that converts pH sensor input (and, in compatible configurations, ORP) into a 4–20 mA signal for process-control systems. It operates from a DC power supply up to 45 V, enabling straightforward installation by sharing loop power with the measurement circuit. Designed to pair with Rosemount pH sensors, the 1181PH provides continuous, real-time pH data for industrial process streams, supporting precise control of chemical dosing, acidity/alkalinity management, and product quality. Typical applications include chemical processing, water and wastewater treatment, and other industries where stable, reliable pH monitoring is critical for safety and efficiency. The transmitter’s two-wire, current-loop interface facilitates easy integration with common control systems and PLCs, delivering a standardized output that can be monitored and logged in plant analytics.