Pneumatic controller

Claim 1

A PNEUMATIC CONTROLLER FOR CONTROLLING FLUID FLOW IN A CONDUIT OR THE LIKE BY VARYING A CONTROL PRESSURE IN ACCORDANCE WITH A PRESSURE DROP IN THE CONDUIT, THE CONTROLLER COMPRISING, A CASING, A PRESSURE-RESPONSIVE DIAPHRAGM DIVIDING THE CASING INTO A PAIR OF CHAMBER, A PAIR OF INLET PORTS IN THE CASING COMMUNICATING WITH SAID CHAMBERS RESPECTIVELY AND ADAPTED TO BE COMMUNICATED IN THE CONDUIT FOR RENDERING SAID DIAPHRAGM MOVABLE IN RESPONSE TO A PRESSURE DROP IN THE CONDUIT, OPPOSED SPRINGS IN THE CASING SEATED AGAINST OPPOSITE SIDES OF THE DIAPHRAGM AND BIASING THE SAME TO A PRE-DETERMINED CONTROL POSITION, A HOUSING CONNECTED TO THE CASING, MEANS FOR VARYING FLUID FLOW THROUGH THE CONDUIT INCLUDING A CONTROL CHAMBER IN THE HOUSING HAVING A SUPPLY PORT AND A DELIVERY PORT, A LEAK PORT IN THE HOUSING COMMUNICATING WITH SAID CHAMBER, A PIVOTED FLAPPER VALVE IN THE HOUSING MOVABLE RELATIVE TO THE LEAK PORT TO CONTROL THE PRESSURE IN SAID CONTROL CHAMBER, AN OPENING IN THE CASING BETWEEN ONE OF THE CHAMBERS AND SAID HOUSING, A FLEXIBLE SEAL CLOSING SAID OPENING, AND A VALVE ACTUATING STEM CARRIED BY SAID DIAPHRAGM AND SAID FLEXIBLE SEAL FOR ACTUATING SAID FLAPPER VALVE IN RESPONSE TO MOVEMENT OF SAID DIAPHRAGM AS DETERMINED BY THE PRESSURE DROP IN THE CONDUIT.