Siemens 171K-10301S 2W 1/2", 0.63CV BALL VALVE ASSY, STAINLESS STEEL BALL AND STEM, 2-10 V, NO, SRSiemens 171K 10301S This 599 Series 2 way ball valve with a 2 10 Vdc control, normally open, 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 0. 63 Cv, equal percentage flow characteristic, with stainless steel ball and stem, and an operating handle that can manually operate