Patent GB-786872-A (GB)
Title: Apparatus for affording rapid relief of pressure
IPC: F16K17/40
Filed: 1953-05-13
Abstract: 786,872. Photo-electric safety device. GRAVINER MANUFACTURING CO., Ltd., MATHISEN, A., and WILKINSON SWORD, Ltd., [formerly WILKINSON SWORD CO., Ltd.]. May 7, 1954 [May 13, 1953; June 26, 1953; June 26, 1953; Nov. 12, 1953], Nos. 13363/53, 17760/53, 17761/53 and 31363/53. Class 40 (3). [Also in Group XXIX] Apparatus for affording rapid relief of excess pressure in an enclosed zone comprises means for detecting the illumination of the flame or of the source of ignition of an explosion in the incipient stage, and means for automatically utilizing the detection signal to operate an explosive charge for opening a normally closed venting aperture in a wall of the zone or for making an opening in the wall. A plant comprises a vessel 10, Fig. 1, where powder is produced and passed by a pipe 12 to a cyclone filter 13 and thence by a pipe 14 and fan 15 to a bag filter 16. Powder in the filters is drawn off through discharge control valves 17, 18 and in the container 10 through hoppers 1Oc pipes 10b and a discharge control valve 11. Explosion detection means 19, 20, 21, 22 are provided, and may be photo-electric cells, such as described in Specification 749,597. Suppressant discharging devices 23a, 23b and 24a, 24b, which may be as described in Specifications 643,188, 682,988, 749,583 or 749,591, [all in Group XXI], are provided. A device for discharging into the inclined pipes 10b, 12 comprises a manifold 23a, 24a containing liquid suppressant and sealed at each end by a frangible diaphragm, one end of the manifold entering the pipe and the other end united to an opening of a gas reservoir 23b, 24b sealed by an explosively operated frangible diaphragm, on, bursting of which the gas bursts the other two diaphragms. The suppressant discharging devices are operated by the detectors. Pressure is relieved in the vessel 10 by opening the roof panels 10a, which are urged into open position by weights 25a on arms 25 and normally held closed by struts 26, Figs. 1 and 4, each leading to a catch 27. An explosive charge in the form of a detonator is housed in a tie-bar 28, and on ignition of the charge electrically by the detectors through a terminal box 32, the bar 28 is shattered, releasing the lower end of the strut 26 to open the panel. The struts 26 and arms 25 may be linked by members designed to release at a certain pressure, in case the catches do not operate. The roof may be urged into the open position by a spring and held shut by a similar catch mounted in an inverted position. In an alternative form of catch, Fig. 10, ignition of a charge 82 forces up a lid 80a, hinged at 80b, against a spring 81, whereupon a finger 85 releases a member 86, which thereupon moves to open a relief vent. Alternatively, the roof may be urged to closed position and opened by a blow from an explosively operated actuator, such as is shown in Fig. 11. Ignition of an explosive charge breaks a tie-bar 95, whereupon a spring 93 forces a ram 91 outwards. Any conventional pressure relief means may be used for the cyclone filter 13. For the bag filter 16, a bursting disc is used, fixed over an aperture 16a in the filter, as shown in Fig. 6. Two armour plate glass discs 40a, 40b are spaced apart, and on ignition of a detonator 46 by the detectors, a pin 45 is projected and the discs are shattered. In another form, two dished discs 60a, 60b, Fig. 8, enclose a space 61 filled with water, and ignition of a detonator 62 shatters both discs. The discs may be of brittle plastic or of ductile material such as silver or copper. The invention can also be applied to aircraft fuel tanks. A rubber bag tank 100, Fig. 12, fitted in a wing 101 is provided with a relief panel 102, which is broken on ignition by a detector of an explosive cord 103, which may be of " Cordtex " (Registered Trade Mark). The detector may be as above. The panel may be of thin metal, such as silver or copper, or of armour plate glass. Alternatively, the panel may be in the wing, and on breaking of it the tank blows out through the opening. Suppressant may be distributed as described in Specification 643,188, [Group XXI]. In another form, where the tank lies against the wing, the cord is sandwiched between the wing and the tank and on ignition tears an aperture in the wing and bursts the tank. Specifications 582,312, [Group XL], 719,622, [Group XXXVII], 743,326, [Group XXIX], 786,871, [Group XXXVII], and 786,874, [Group XXIX], also are referred to.