What main function does the valve stem serve in a stop check valve?

The valve stem in a stop check valve primarily serves to control the lift of the disk. This is essential because the disk is responsible for regulating the flow of fluid through the valve. By adjusting the position of the valve stem, the disk can either open or close to allow or restrict fluid flow. This mechanism is crucial in situations where precise control of fluid movement is necessary, such as in piping systems where backflow prevention and surge protection are critical.

The design of the valve ensures that when the flow is directed in the proper direction, the disk is allowed to lift, facilitating fluid passage. In the case of reverse flow, the disk automatically seats itself to prevent backflow, showcasing the stem's role not only in control but also in ensuring safe and efficient system operations. This function is fundamental to the effective operation of a stop check valve in various applications across different industries.