Patent GB-1387345-A (GB)
Title: Distribution outlets for high pressure fluid systems
IPC: G05D16/18
Filed: 1972-09-11
Abstract: 1387345 Gas distribution systems WILMOT BREEDEN (TRUFLO) Ltd 5 Sept 1973 [11 Sept 1972 23 Oct 1972] 42130/72 and 48809/72 Heading F4X [Also in Division G3] A distribution outlet for providing a low pressure gas supply 15 (e.g. 30 p.s.i.), from a high pressure gas supply 10 (e.g. 250 p.s.i.), comprises first and second fluid paths 13, 14, the first path including a pressure governor 19 for reducing the pressure to a value P1 and a flow control valve 18, and the second path including a governor 21 for reducing the pressure to a value P2 less than P1 and a flow control valve 20, a first pressure responsive means 35, 40 and actuator 22 to close the valve 18 when the pressure in the outlet exceeds a value P3 greater than P1, and a second pressure responsive means 36, 45 and actuator 23 to close the valve 20 when the pressure in the outlet exceeds a value P4 greater than P3. In the preferred embodiment, the supply 10 at 250 p.s.i. is reduced by the governor 19 to 30 p.s.i. while the governor 21 is set to 28 p.s.i. and is therefore normally closed. If the pressure in the supply 15 falls due to increased demand, the governor 21 opens the second path to provide an increased supply. A rise in pressure at the supply 15 to a value of 34 p.s.i. causes a sensor 40 and a relay switch 35 to operate a valve 25 which causes an actuator 22 to close the valve 18 so that only the second path is open. A further rise in pressure at the supply 15 to a value of 38 p.s.i. causes a sensor 45 and a relay switch 36 to operate a valve 27 which causes an actuator 23 to close the valve 20. The second flow path remains closed until the valve 27 is manually reset. A fall in pressure in the supply 15 to a value of 38 p.s.i. causes a sensor 45 and a relay switch 36 to operate a valve 27 which causes an actuator 23 to close the valve 20. The second flow path remains closed until the valve 27 is manually reset. A fall in pressure in the supply 15 to a value of 25 p.s.i., however, will again operate the relay 35 to open the valve 18, automatic resetting in this way being permitted a predetermined number of times, say 3, by a counter 43. The fluid supply for the control system is obtained from the high pressure gas main and is reduced by regulators 29, 33 fitted with gauges to a value of 80 p.s.i. A filter 28 and a lubricator 34, when the fluid is natural gas, may also be provided. In practice two governors are provided in each path, and a number of stand-by paths arranged to come into operation at successively lower pressures may be used. Indicators operated by flame-proof switches on the actuators 22, 23 may be provided. In a modified control unit, both paths are provided with automatic reset so that cyclic switching occurs and the system acts as an on-off governor when a fault occurs in both paths. A manual change-over valve enables either path to be selected as the stand-by path. In further modifications each flow path is constructed as a separate unit or module or three flow paths are combined in a single module with a three-way key-operated control valve to enable the flow control valve in any of the paths to be closed.