What is NOT a final control element?

A final control element is a device that directly influences the behavior of a process. In this context, the primary function of final control elements is to adjust the flow of a medium, such as liquids or gases, based on signals from control systems.

The correct choice, which is piping, does not act directly as a control element. While piping is critical in carrying fluids within a system, it does not provide any modulation or adjustment to the flow on its own. Instead, it serves as a conduit for the medium being controlled. In contrast, control valves, pneumatic actuators, and electric motors are all capable of adjusting the flow or position based on a control signal, hence qualifying them as final control elements.

In summary, the distinction lies in the function: final control elements actively modify conditions in the process, whereas piping strictly serves a transport role without any inherent ability to control flow or pressure.