Siemens 172K-10304S 2W 1/2", 2.5CV BALL VALVE ASSY, STAINLESS STEEL BALL AND STEM, 2-10 V, NC, SRSiemens 172K 10304S This 599 Series 2 way ball valve with a 2 10 Vdc control, normally closed, fail safe actuator assembly, providing 200 psi close off, is used to control hot or chilled water and up to 50% Glycol solution in convectors, fan coil units, unit conditioners, radiation and reheat coils. This 1 2 inch valve is 2. 5 Cv, equal percentage flow characteristic, with stainless steel ball and stem, and an operating handle that can manually