Device for controlling the supply of a combustible gas to a burner apparatus

A device for controlling the supply of a combustible gas to a burner apparatus, comprising a main gas supply pipe in which are disposed a first and a second servovalve, respectively in cascade with each other, with respect to the direction of flow of the gas, said servovalves including respective valve seats associated with a corresponding shut-off member with diaphragm control for the opening of said seats in opposition to respective resilient return member, said first and second servovalve comprising a respective first and second control solenoid valve with an electromagnetic operating device that controls the opening/closure of the corresponding servovalve, said solenoid valves being arranged to act for opening/closure of pipes of respective servo-assisted control circuits, so as to control indirectly, by way of the diaphragm control, the respective shut-off member of the corresponding servovalve, the pipes of the control circuit placing the main pipe in fluid communication with respective control chambers of the servovalves, one side of the diaphragms of said diaphragm controls being subjected to the pressure existing in the respective control chamber, both of the intake pipes of the respective control circuits, capable of picking up the pressure signal to be transmitted to the corresponding control chamber, being respectively connected, in fluid communication, with the main pipe, upstream of the first servovalve, through an auxiliary bleed pipe which is branched from the main pipe, a pilot pipe is branched from the auxiliary pipe to supply a pilot burner, and a thermoelectric magnetic safety unit with a manual activating knob is provided on said auxiliary pipe, said unit acting on the pilot pipe so as to allow gas to flow towards the pilot burner when the unit is activated, while simultaneously shutting off the flow of gas towards the servovalve control circuit, and;

• a control mechanism that controls the flow of gas to the control circuit, the control mechanism being controlled by the knob of said magnetic unit in operation, in order to open selectively the flow of gas towards the pipes of the servovalve control circuit, after the magnetic unit has been activated and when a flame is present at the pilot burner.