This document provides the operating instructions for the +GF+ SIGNET 2551 electromagnetic flow meter from Georg Fischer Piping Systems Ltd. It includes a quick start guide, product specifications, installation of fittings, selection of installation location, construction of the 2551 flow meter, technical tips for installation and grounding, wiring of the 4-20mA or frequency/digital signals, preparation and configuration of the user system, use of the i-Go converter and debugging tool, setting of average and sensitivity values, calibration data, maintenance, and ordering information.