Answers to what makes an instrument reliable and maintainable frequently lie outside the manufacturers' manuals. These sometimes are revised procedures, test methods, or physical modifications. This book provides complete information for 26 widely used instruments including pumps and valves used in process control. This includes application, principle of operation, accuracy and repeatability, manufacture's options, installation, designer checklist, maintenance and calibration, deficiencies, and references. It is a guide to for the selection, application, and maintenance of primary elements and final control elements.