Which of the following devices is used for measuring and controlling flow in fluid systems?

The flowmeter is specifically designed to measure the flow rate of liquids and gases within a fluid system. It provides critical information about how much fluid is passing through a given point in a specific time frame, which is essential for various applications, including industrial processes, water management, and even HVAC systems.

Flowmeters come in various types, such as differential pressure, electromagnetic, and ultrasonic, each suited for different fluids and conditions. They not only measure the flow but can also be integrated into control systems to regulate the flow based on predetermined settings, making them invaluable for maintaining system efficiency and safety.

In contrast, other devices listed serve different purposes: a filter is primarily used to remove impurities from fluids, a separator is designed to divide different components within a mixture (like oil and water), and a compressor is used to increase the pressure of gases. Each of these plays a distinct role in fluid systems but does not focus on measuring and controlling flow like a flowmeter does.