What is a ball valve and how is it used for control?

A ball valve uses a rotating ball with a bore to control flow. The ball rotates 90 degrees - aligned bore is open, perpendicular is closed. For control applications: segmented ball (V-notch) provides characterized flow with better rangeability than full-bore ball. Characteristics: compact, low torque, tight shutoff, high capacity (Cv), and suitable for slurries and viscous fluids. Used in: severe service, high temperature/pressure, and abrasive applications. Less precise than globe for fine control but offers advantages in specific applications like pulp and paper, mining, and chemical.