GB1093411A - Improvements in thermostatically controlled gas valves - Google Patents

Abstract

1,093,411. Fluid-pressure servomotor systems. BRITISH THERMOSTAT Ltd. Sept.9, 1965 [June 19, 1964], No. 25485/64. Heading G3P. [Also in Divisions F2 and F4] A relay valve (20) Fig. 2 (not shown) controlling the gas supply to a burner (23) for a boiler (24), is controlled by a pressure set up by a weep valve (1) of which the inlet 7 is connected to the relay valve and the outlet 8 to the supply pipe next to the burner. The weep valve is responsive to its outlet pressure on a diaphragm 4 tending to close the valve member 2, and a resilient loading tending to open it, is applied to the valve stem 12 through a spring blade 11 in response to the temperature in the boiler sensed by a phial 15 connected to a bellows 14. The blade 11 is fixed to a lever 9 moved by expansion of the bellows in a direction to reduce and finally to remove the spring-loading when an abutment 13 engages the blade. A stop 18 limits the application of the loading when the boiler is cold and the gas pressure is controlled at the highest required value. A micro-switch 32 operated by the lever as the loading is removed, controls a magnetic valve (not shown) in the weep line between the two valves. In a modification, the lever is held in inoperative position, by a magnet and keeper (27, 28) Fig. 3 (not shown) and a bi-metal (29) when heated by a coil (31) deflects to allow the valve to open under a biasing spring 17.