The pH electrode offers by far the greatest sensitivity and rangeability of any industrial process measurement. To realize the full potential of this opportunity requires extrao rd inary performance of mixing equipment, contro l valves, reagent delivery systems, flow meters, control system design, and controller tuning. This book is designed to cover all of the bases but not get the user lost in the details. Since each of these topics could be a book in itself, the emphasis here is on cutting straight to the chase of concepts critical for a successful pH system. Key insights and rules of thumb a rc inserted to congeal principles and practices that address the essential requirements of pH applications. The book should appeal to both the generalist and the specialist. This book is designed to bring togethe r the chemist, control engineer, instrument technician, process engineer, and project manager to literally and figuratively put them on the same page.