Patent ID: 8162002

Claim:
A device for controlling the delivery of a combustible gas to a burner apparatus, comprising a main gas-delivery duct ( 2 ) in which there is at least one servo-assisted diaphragm valve ( 5 ) including a valve seat ( 5 a ) associated with a corresponding closure member ( 5 b ) with diaphragm control ( 6 ) for opening the seat against the action of a resilient biasing member ( 7 ), the diaphragm valve ( 5 ) comprising a respective control solenoid valve ( 8 ) with an electromagnetic operator for controlling the opening/closure of the corresponding valve ( 5 ), the solenoid valve being arranged to bring about the opening/closure of a duct ( 9 ) of a respective servo-assisted control circuit so as to operate the closure member ( 5 b ) of the valve ( 5 ) indirectly, by the diaphragm control, the duct of the control circuit putting a portion of the main duct ( 2 ) that is disposed upstream of the valve seat ( 5 a ) with respect to a direction of the gas-flow into flow communication with a respective control chamber ( 10 ) of the diaphragm valve, a first side ( 6 a ) of the diaphragm ( 6 ) of the diaphragm control being subjected to the pressure existing in the respective control chamber ( 10 ), the second, opposite side ( 6 b ) of the diaphragm ( 6 ) delimits a space ( 21 ) which is separated from the portion of the main duct ( 2 ) that extends downstream of the valve seat so that the second side ( 6 b ) of the diaphragm is not subjected to the delivery pressure of the gas that is present in the duct portion, downstream of the valve seat ( 5 a ); wherein a second diaphragm ( 24 ) and the closure member ( 5 b ) have respective facing sides which have respective surface extensions that are substantially equivalent to one another so as to render the resultant of stresses generated in the device by the pressures acting on the facing sides of the closure member and of the second diaphragm generally such as to have no effect or even to be zero.