What instrument would you use to measure flow rate in a pipeline?

A flowmeter is the correct instrument to measure flow rate in a pipeline because it is specifically designed to quantify the amount of fluid moving through a system over a given period of time. Flowmeters can utilize various principles such as differential pressure, electromagnetic, or ultrasonic technology to provide accurate measurements of liquid or gas flow in pipelines. They are essential in many industrial applications, where monitoring flow rates can help in optimizing processes, ensuring safety, and maintaining equipment integrity.

In contrast, a thermometer measures temperature, which does not provide information about flow rate. A pressure gauge is used to measure the pressure within a system, which, while it can relate to flow in specific contexts, does not directly give the flow rate. A level transmitter measures the level of liquid within a tank or vessel, which again does not provide direct flow rate data but rather the volume or level of liquid present.