Abstract: A fail-safe, precision current-to-pressure converter for providing a regulated pneumatic output pressure proportional to an electrical control current includes a main valve member for regulating the pneumatic output pressure, operation of the valve member being controlled by the pressure of control fluid contained in a chamber. The control fluid pressure is controlled by admitting control fluid into the chamber via a continuously pulsed, electromagnetically actuated on/off reed valve and simultaneously allowing control fluid continuously to exhaust to atmosphere via a fixed bleed orifice, the rate of admittance of control fluid into the chamber relative to the exhaust rate from the orifice being variable so that the desired, substantially constant output pressure, as dictated by the electrical current input and as measured by a transducer that produces a feed-back signal, will be attained.

Abstract: A pneumatic regulator in the form of an electro-pneumatic device (an I/P regulaor) in which the pressure of pneuamtic medium is controlled in response to an electrical signal in which the pneumatic pressure regulator incorporates a control volume whose pressure is used to regulate the main pneumatic pressure and the pressure in the control volume being under the control of pneumatic valves, the valves being opened and closed by electrical signals provided by an electrical circuit, which circuit incorporates electrical storage so as to permit the electrical circuitry to operate the valve on currents in the range 4-20 mA so that the electro-pneumatic regulator can be operated directly by electronic control systems without the need of supplementary electrical feeds.