Flexible Automatic Pressure Regulator is facilitated with high-precision pressure sensors and high resolution, fast response piezo actuator valves. The Automatic Pressure Regulator can control the pressure relative to the external control signal that they receive. The Automatic Pressure Regulator has the gas contact area available in all-metal construction which makes it ideal for ultra-clean pressure control of ultra pure gas supply systems. Flexible Automatic Pressure Regulator can be mounted in any position or attitude and as it uses an electric signal for control to make them suitable for a wide variety of gas supply systems.