In a piping system, what function does the valve stem serve?

The valve stem plays a crucial role in controlling the flow of fluid through a valve. When the valve is turned or actuated via the stem, it moves the internal mechanism, such as a disc, gate, or ball, that opens or closes the flow path inside the valve. This action directly regulates the quantity of fluid that passes through the valve, either allowing it to flow or stopping it entirely.

Each valve design will have a unique mechanism to either throttle (control the flow rate) or fully stop the flow, but all of them rely on the valve stem to transmit the operator's commands to the internal parts of the valve. Consequently, the valve stem is essential for the effective functioning of any piping system where flow control is necessary.