What device is utilized to create flow in a liquid system?

A pump is the device specifically designed to create flow in a liquid system. Pumps operate by moving liquids through mechanical action, which can be achieved through various means such as positive displacement or centrifugal force. By generating pressure, pumps facilitate the movement of liquid from one location to another, allowing for efficient transportation in applications like tankers or pipelines.

While valves are essential in managing and controlling the flow of liquid within a system, they do not create flow by themselves. Valves are used to open, close, or regulate flow, rather than initiate it. Couplings serve as connectors between different sections of pipes or hoses without creating flow. Compressors are primarily associated with gases rather than liquids and are used to increase the pressure of gases. Therefore, a pump is the ideal choice for generating flow within a liquid system.