Siemens SKB82.51U FLOWRITE ELECTRO-HYDRAULIC ACTUATOR, FLOAT CONTROL, SPRING RTN, 3/4-IN STROKESiemens SKB82. 51U Flowrite Electro Hydraulic Actuator, Float Control, Spring Rtn, 3 4 in Stroke The Flowrite SKB Valve Actuator is used with Flowrite and other standard valves with a 3 4 inch stroke. This electronic valve actuator requires a 24 Vac supply to provide floating control of the valve. Other features of this valve actuator include automatic stroke calibration, manual override, die cast aluminum housing, 1000 lb (4000N) thrust, and spring