The HPP-4 provides accurate valve positioning when utilized with a double-acting piston actuated control valve. The HPP-4 accepts a pneumatic instrument signal and positions the double-acting actuator proportionally. The HPP-4 Positioner may be utilized for most valve positioning applications. HPP-4’s are available in both reverse acting and direct acting configurations with a variety of different input signal ranges. The HPP-4 is typically utilized when Bleed to Pressure System (BPS)™ may be used to completely eliminate atmospheric bleed emissions.