GB407340A - Improvements in or relating to valve devices for automatically controlling the flow of gas in pipes - Google Patents

Abstract

407,340. Safety cut-off valves. EVANS, G. M., Charter Street, Archdeacon Lane, Leicester. Sept. 14, 1932, No. 25573. [Class 135.] In a safety cut-off device, particularly for use with prepayment meters, and comprising a valve which closes on failure of the gas pressure, but which although held open by the normal gas pressure cannot be opened thereby on its restoration until re-set by hand, a weight which normally partly counterbalances the weight of the valve falls over and drives the valve, consisting of a conical cap, firmly on to a conical nozzle forming the seat. In Fig. 1 the device is shown mounted on a cock 4 for controlling the supply of gas to a burner connected at 3. The valve 8 when raised permits gas to pass from the nozzle 6 to a recess 7 and thence, when the cock 4 has been rotated by a handle 16 after turning-on a pilot jet 13<a>, by a passage 9 to the burner. In either position of the cock 4, normal gas pressure will raise the valve 8 when a weight 21 pivoted at 22 is in the position shown in Fig. 6, wherein it presses on the outer end of a lever 18, pivoted at 19 and connected to the valve. On failure of the gas supply, the valve 8 descends by gravity, rotating anticlockwise the weight 21 which finally falls over to the other side of the pivot 19 of the lever 18, delivering a hammer-blow on the valve and holding it closed against the gas pressure when restored. Manual means for opening the valve in these circumstances comprise a carrier 30, Fig. 3, rotatable on the front casing 25 by a knob 27 and carrying an arm 32 with counterbalance 35, eccentrically pivoted in a slot 31. Rotation of the knob 27 clockwise as seen in Fig. 1, by means of engaging lugs 34, 24 carries the weight 21 into engagement with the roller 20 of the lever 18, opening the valve ; the lug 34 then escapes from lug 24, so that the valve only remains open however, if the pressure at 2 is sufficient. The knob 27 and carrier 30 may be returned by a spring. In the fully open position the valve 8 seats by a flange 8<a> against the part 11, a groove in the flange allowing a small amount of gas to pass.