What are the common control signal ranges for valve actuators?

Common control signals: 4-20 mA (standard electronic signal - 4 mA = 0%, 20 mA = 100%), 3-15 psi (standard pneumatic signal), 6-30 psi (double-pressure pneumatic for higher thrust), and digital protocols (HART, Foundation Fieldbus, PROFIBUS PA). Signal conversion: I/P converter changes 4-20 mA to 3-15 psi for pneumatic actuators. Smart positioners accept electronic signal directly and control actuator pressure. Split-range uses different portions of signal (e.g., 4-12 mA for valve 1, 12-20 mA for valve 2).