Patent GB-708740-A (GB)
Abstract: 708,740. Thermally-actuated valves. ROBERTSHAW-FULTON CONTROLS CO. July 11, 1951 [July 15, 1950], No. 16450/51. Class 135. [Also in Group XI] In a flame-failure control and ignition apparatus for fluid fuel burning appliances having a main burner 10, and a pilot burner 12, ignitible by an ignition burner 104, a valve device 24 controls the fuel supply to the main and ignition burners by means of a dual valve member 40, 50, biased towards one 34 of a pair of oppositely disposed valve seats 34, 48 whereby the fuel supply is prevented to the main burner 10 and permitted to the ignition burner 104, thermally responsive means 84, 88 operated by the presence of a flame at the pilot burner 12 being arranged to move said valve member 40, 50 against its bias towards the other 48 of said valve seats whereby the fuel supply is permitted to the main burner 10 and prevented to the ignition burner 104. As shown, a gas cock 18 supplies gas direct to the pilot burner 12 via a pipe 16, and to the main and ignition burners via the valve device 24. The valve device 24 has a casing 26 with a gas inlet 28 and a main burner outlet 30 connected via a passage 32 interrupted by an annular valve seat 34 formed with a hollow central guide 36. A hollowended valve stem 38 s'ides in the guide 36 and supports a disc valve 40 urged by a spring 42, abutting a closure cap 44 of the casing towards the valve seat 34. The valve stem 38 has retained in the bore thereof, against an over-ride spring 54, a poppet valve 52 the head 50 of which co-operates with the valve seat 48 arranged in the closure cap 44, from which latter a pipe 106 supplies the ignition burner 104. The valve 52 is held in valve stem 38 by a plate 58, on the valve disc 40, engaging a collar 56 on the valve 52. The lower end of valve stem 38 has an adjusting screw 60 acted on by levers 64 which transmit the movement of a snap-action disc 66 held within a recess 62 in the valve casing 26. The snap-action disc 66 is actuated bv a thrust button 68 through an element 70, the button 68 being actuated through levers 76, 80 by a stud 90 of an expansible diaphragm element 88. The element 88 is connected by capillary tubing 86 with a bulb 84 sited in the path of the pilot burner flame and charged with mercury arranged to vaporize at 1000‹ F. On such vaporization the element 88 is expanded to cause the disc 66 to move to the position shown whereby the valves 40, 50 are unseated and seated respectively on their seats 34, 48. In operation, failure of the flame at the pilot burner 12 causes contraction of the expansible element 88 so that valve 40 is moved by its spring 42 to close the gas supply to the main burner, and valve 50 is retracted from its seating 48 to permit gas supply to the ignition burner 104, the snap-action disc 66 being returned to its initial position. The ignition burner 104 is ignited via a flash tube 102 from a constant burning pilot 100. The pilot burner 12 is then ignited by ignition burner 104 and when the bulb 84 is heated sufficiently the snap-action disc 66 is actuated by element 88 to open valve 40 and close valve 50. The valve device may be calibrated by means of a screwthreaded nipple 92 carrying the element 88 and screwed into a cover member 94 enclosing the levers 76, 80.