Valves that we use perform one of two functions – they either shut-off or throttle flow. In general, most valve designs are capable of either of these functions. However, in actual use in applications, the functional roles are usually pre-determined – some valves are meant to shutoff and others to throttle, either manually or automatically. Of course, there are exceptions, typically some manually operated valves that are provided to function in both roles as may be required.
Have you read this Valve World Americas special topic article? Take five minutes to read it now: https://www.valve-world-americas.com/pdf/202102_11.pdf