These valves are used on the discharge side of a centrifugal pump in a hydronic heating or cooling system and act as a shut off valve, a spring loaded silent check valve, and balancing valve. They are made from cast iron castings and machined to exact requirements along with drilled flanges in the bodies. A center soft seal disc assures no leakage and the rising stem configuration comes with an adjustable position indicator for accurate disc positioning for throttling service. The inlet, outlet includes a standard gauge tap and an NPT drain plug. There is both silence and automatic operation and discs will open when line pressure reaches ¼ PSI. To stop flow reversal and water hammer, a spring will close the disco as the line pressure gets closer to zero. The acme rising stem allows for the valve flow to be adjusted.