What is achieved by using a valve in a piping system?

Using a valve in a piping system primarily allows for the regulation and control of fluid flow. Valves serve as mechanical devices that can partially or fully block off the flow of liquids or gases. By adjusting the position of the valve—whether it be opening, closing, or throttling—operators can precisely control the volume and rate of the fluid passing through the system. This capability is crucial in processes where maintaining specific flow rates is necessary for efficiency and safety, enabling various applications such as adjusting pressure levels, managing temperature, and ensuring proper chemical reactions in industrial processes.

While other aspects of valves can involve isolation of equipment or impact on flow characteristics, their primary role centers on controlling how much fluid flows through a system and at what rate, making choice B the most fitting answer in the context of this question.