Three-way safety double valve

Claim 1

A THREE-WAY DOUBLE VALVE UNIT FOR CONTROLLING THE FLOW OF A PRESSURE MEDIUM TO A PRESSURE-OPERATED APPARATUS AND ADAPTED, WHEN A FAILURE OCCURS IN THE OPERATION OF SAID VALVE UNIT, TO INTERRUPT SAID FLOW, SAID VALVE UNIT COMPRISING A VALVE HOUSING, A MAIN INTAKE CONDUIT WITHIN SAID HOUSINF ADAPTED TO BE CONNECTED TO A SUPPLY LINE FOR SAID PRESSURE MEDIUM, A PAIR OF THREE-WAY MAIN CONTROL VALVES ARRANGED IN SERIES IN SAID HOUSING AND BOTH CONNECTED TO SAID MAIN INTAKE CONDUIT AND ADAPTED TO COMMUNICATE WITH AT LEAST ONE OUTLET ADAPTED TO BE CONNECTED TO SAID APPARATUS, A PAIR OF CHAMBERS IN SAID HOUSING ABOVE SAID MAIN CONTROL VALVES, A PAIR OF THREE-WAY SAFETY VALVES, EACH POSITIVELY CONNECTED TO ONE OF SAID MAIN CONTROL VALVES SO AS TO BE MOVABLE THEREBY, SAID MAIN CONTROL VALVES AND SAID SAFETY VALVES HAVING SUBSTANTIALLY FLAT VALVE MEMBERS FOR OPENING AND CLOSING, THE ASSOCIATED VALVE SEATS OF SAID VALVES, A FEED CONDUIT WITHIN SAID HOUSING CONNECTED TO SAID MAIN INTAKE CONDUIT, A PAIR OF PRELIMINARY CONATROL VALVES EACH CONNECTED WITH SAID FEED LINE AND WITH SAID CHAMBER ABOVE THE ASSOCIATED MAIN CONTROL VALVE FOR MOVING THE LATTER BY SAID PRESSURE MEDIUM TO THE ON POSITION WHEN SAID PRELIMINARY CONTROL VALVE IS OPENED, MEANS FOR MOVING SAID PRELIMINARY CONTROL VALVES FROM THE CLOSED TO THE OPEN POSITION AND FOR MOVING SAID MAIN CONTROL VALVES SIMULTANEOUSLY TO THE ON POSITION WHEN BOTH OF SAID PRELIMINARY VALVES ARE OPENED SIMULTANEOUSLY, EACH OF SAID SAFETY VALVES HAVING AT LEAST ONE