Electronically controlled gas pressure regulator - uses current-to-pressure converter and pneumatic control

摘要

A gas supply entering pipe (1a) at left passes through a flow regulator valve (1) before leaving at a pipe (1b), connected via a sensing pipe (1c) to the underside of a diaphragm (3). A spring (22a) of a cut-off valve (22) is set at a lower pressure limit e.g. 1 BAR, that of a cut-off valve (24) to an upper limit e.g. 10 BAR. Within this range, the first valve (22) is closed and the second valve (24) is open, with a pipe (4) at the supply pressure. A diaphragm (8) of an amplifying valve (5) has the output pressure of the I/P converter (14), via an overpressure safety valve (21), applied above and atmosphere via a vent (20) applied below, and is mechanically joined to a diaphragm (7) which has atmosphere above and gas output pressure below via the pipe (4) and a flow restrictor (19). A valve (10) on another diaphragm (6) opens and closes to admit or shut off gas supply pressure above the first diaphragm (3) which directly controls a flow regulating valve (4a). Thus gas pressure at the output (1b) is maintained proportional to air pressure output (13) of the I/P converter (14) under control of a current input (16). A compressed air supply is connected to another pipe (15). ADVANTAGE - Operation with low differential between supply and output gas pressures.