GB1436432A - Gas control device - Google Patents

Abstract

1436432 Valves CONCENTRIC CONTROLS Ltd and MAIN GAS APPLIANCES Ltd 19 Dec 1974 [20 Sept 1973] 44112/73 Heading F2V [Also in Division F4] A gas control device comprises a thermostat valve 10 having a valve member 16 mounted on a support 14 and movable through a range of positions relative to a valve seat 22, the position being determined by the combined efforts of a thermo-sensitive device (not shown) and an adjustable setting device (not shown), the thermo-sensitive device including a probe (not shown) and an expansion element 25 which is contracted when the probe is cool to cause valve member 16 to open, but as the temperature of the probe rises the element 25 expands and closes the valve 16, the particular adjustment of the setting device determining the temperature to which the probe must be heated to cause the valve member to reach the closed position, and a flame-sensing device comprising a probe (not shown), and an expansion element 34, wherein when the probe is cool, element 34 is contracted, but when the probe is heated by a gas flame, element 34 expands, element 34 and valve member 16 are arranged so that if the probe of the flame-sensing device cools and element 34 consequently contracts, the contraction overrides the normal operation of the thermostat valve and results in the valve member 16 moving to its closed position, but when the probe of the flame-sensing device is heated by a gas flame and element 34 is expanded the element does not interfere with the normal operation of the thermostat valve. The adjustable setting device comprises a rotary plug valve (not shown), which controls the flow of gas to a chamber 11 and has a cam track co-operating with a slidable rod 12 which engages a beam 14 carrying valve 16. In operation, a gas burner is controlled by turning the plug valve to allow sufficient gas to pass through a by-pass to enable the burner to be lit; valve 16 being closed. A mercury-filled probe is heated and the mercury expands in passage 35 and element 34 so that a rod 37 pivots a lever 39 to compress a spring 43, and a spring 21 opens valve 16 so as to increase the gas flow to the burner. A probe is connected to an oil filled conduit 30 and element 25, the latter expands to pivot beam 14, to thus urge valve 16 in the direction of the closed position in accordance with the particular position of rod 12 which is controlled by the setting of the plug valve. If the flame of the burner goes out, the mercury-filled probe cools, lever 39 rocks and spring 43 closes valve 16 to thus cut off the fuel supply to the burner. The mercury-filled probe may be heated by a pilot, independent of the plug valve, in which case the by-pass is omitted. A different lay-out of rods 37, 12, and their controls is described.