| 摘要 |
1,266,511. Valves. ANDERSON, GREENWOOD & CO. 12 May, 1969 [6 Feb., 1969], No. 24099/69. Heading F2V. [Also in Division G3] A main pressure relieving valve 14 for a container T is controlled by a pilot valve P responsive to the pressure in the container and having its outlet connected to pressure responsive actuating means 16 for the main valve, a back flow preventer 22 serving to connect the means 16 to the pilot valve or to a line 24 leading to the main valve outlet if that is at a higher pressure. Fluid from the container flows through line 18 to a port 54 and the inlet 52 of the pilot valve. Normally open valve seats 44, 46 and the spacers between a polygonal closure member 90 and a cylindrical cage 40 provide communication with a chamber 66 where the fluid lifts a second closure member 78 from a seat 48 against the resistance of an adjustable spring 80 when a predetermined pressure is reached. An increased area of closure member 78 is exposed to the pressure in chamber 66 once the member has cracked open so that the fully open position is rapidly reached. Closure member 90 now engages seat 46 to shut off the supply of fluid while the space above the pressure responsive member 16 is connected to a vent 26 through the back flow preventer 22 and a line 20 to allow the main valve 14 to open. The pressure at which the valve 78 closes is determined by the spacing between the seats 46 and 48 and this spacing may be adjusted by rotating the cage 40 which has a threaded connection with the pilot valve housing. A test pressure source 116, a gauge 118 and a valve 120 are used to set the opening pressure of the valve 78, the closure member 90 then engaging the seat 44 to prevent test fluid from entering the container T. A spacer rod 104 ensures that seat 46 is open when seat 48 is closed. The back flow preventer 22 ensures that the member 16 is connected to the greater of the two fluid pressures in the lines 20 and 24 and has a shuttle valve with sealing rings for alternate closure of opposed seats. Specification 1,266,512 is referred to. |
