What are the two principal functions of valves?

The two principal functions of valves revolve around regulating flow and controlling the starting and stopping of that flow within a piping system. Valves play a crucial role in managing the movement of fluids, whether they are liquids or gases, through pipelines.

By regulating flow, valves allow for adjustments to the volume and speed of the fluid moving through the system. This function is essential in maintaining system efficiency, pressure control, and ensuring that the fluid is delivered at the required rate for processes downstream.

Additionally, the capability to start or stop flow is vital for operational safety and control. Being able to shut off flow can prevent accidents, facilitate maintenance, and allow for the isolation of sections of the piping system when needed.

In contrast, the other options present functions that do not encompass the primary purposes served by valves. For example, while controlling temperature and reducing noise might be related to process control, they are secondary effects rather than principal functions. Similarly, filtering impurities and measuring fluid levels are tasks typically associated with other equipment rather than the core purpose of valves.