The HPP-SB Single-Acting Positioner provides accurate valve positioning when utilized with a single-acting (spring and piston style) actuated control valves. The HPP-SB accepts a pneumatic instrument signal and positions the single-acting actuator (spring and piston style) proportionally. The HPP-SB can be utilized with most valve positioning applications. HPP-SBs are available in both reverse-acting and direct-acting configurations with a variety of different input signal ranges. The HPP-SB features a ZERO steady state bleed that minimizes emissions when the positioner must bleed to atmosphere.