Patent GB-718273-A (GB)
Title: Control apparatus for gas, liquid-fuel, or atomised-fuel fired burners
IPC: F23N5/10
Filed: 1951-03-27
Abstract: 718,273. Controlling burners. TAYLOR, F. M. H. June 27, 1952, [March 27, 1951.] No. 7123/51. Class 75 (1). A control apparatus for a liquid or gaseous fuel heating appliance incorporating a pilot burner 4 and a main burner B includes a thermocouple 5 which is heated by the pilot burner and holds open a self-closing fuel valve 6 supplying the pilot burner, and a flame detector 7 lying in the field of the pilot and main burners and controlling through an electronic amplifier a valve or valves supplying the main burner in such manner that the valve or valves open only when the pilot burner is alight and closes should the pilot and main burner flames fail. Pressure air is supplied to the main burner through a slow opening main valve 1, and through a by-pass valve 2 and gas at atmospheric pressure is supplied to the main burner through a pressure governor F and a fuel valve 3. The main burner valves 1, 2, 3 are operated by solenoids or by a motor or by air pressure controlled by solenoid valves, and the circuits to the valves include contacts which are closed by the electronic amplifier when energized by the flame detector 7. The electronic amplifier is included in a control unit 12, which has separate push buttons for completing the circuits to the by-pass air valve 2 and to the main air valve 1, and the two buttons may be interlocked so that the main valve button can only be opened after the bye-pass valve. The pilot burner fuel valve 6 is opened by a push button and is held open by an electromagnet energized by the thermo-couple 5; it is disposed adjacent to the heating appliance so that it can be operated by an attendant whilst he applies a lighted torch to the pilot burner. The circuit to the valves 1, 2, 3 supplying air and fuel to the main burner is also controlled by a switch 10 responsive to the pressure of the air supply and by a switch 11 responsive to the pressure of the fuel supply to the pilot burner whereby the valves 1, 2, 3 are closed when the air pressure or the pressure of fuel to the pilot burner is low. The pilot valve may include contacts which ensure that the valves 1, 2, 3 can only open after the pilot valve has opened. The control unit also includes a device for regulating the temperature of the material being heated by the appliance, the device comprising a pyrometer 8 associated with the material and adapted to control the main air valve 1 whereby on a rise in temperature, the main air valve 1 is closed, thus reducing the size of the flame. The pyrometer also actuates a temperature indicator 9. An audible and/or visible warning is given if an excessive temperature is attained or if the fuel or air supplies fail and the contact controlling the warning device may also close down the valves 1, 2, 3. The flame detector 7 may be a flame conduction or a flame rectification or a flame capacitance type. The Provisional Specification states that the apparatus can be interlocked with an induced draught fan or flue damper and can be provided with a time delay device preventing immediate ignition after a shut down.