Which type of valve is used to control flow in a piping system?

A gate valve is specifically designed to control the flow of fluid within a piping system. Its primary function is to either allow or obstruct the flow, functioning best in applications where the valve is either fully open or fully closed. This type of valve achieves minimal pressure drop when fully opened and provides a good sealing capability when closed, which makes it an ideal choice for on/off control.

Though there are other types of valves mentioned, they serve different purposes. For example, a relief valve is intended for safety, allowing excess pressure to escape to prevent system overloads. A pressure gauge is used to measure and indicate pressure levels in a system rather than controlling flow. Similarly, a drain valve is utilized to remove fluids from a system but is not primarily designed for flow regulation. Each of these options has specific applications that do not include the general flow control that a gate valve facilitates.