GB1320364A - Automatic sprinkler system - Google Patents

Abstract

1320364 Accelerator device in dry pipe sprinkler system GRINNELL CORP 31 July 1970 [1 Aug 1969] 37154/70 Heading A5A [Also in Division G3] An accelerator device for a dry pipe valve interconnecting a main to distribution piping in a sprinkler system comprises a first chamber having first and second fluid transfer ports, a pilot valve for closing one of said ports, a second chamber, an operating member extending from within said second chamber and operable to open the pilot valve, and fluidoperated actuating means for actuating the operating member and having a pressure-sensing port, the pressure-sensing port and at least one of the fluid transfer ports being connected to the dry pipe valve, whereby the device in response to a gas pressure change in the distribution piping opens the dry pipe valve, and the fluid of the actuating means is isolated from the extinguishant fluid. In Fig. 2, main dry pipe valve unit 40 coupling water main-41 with distribution piping 42 consists of first valve 43 held on its seat against the main pressure by hinged second valve 44 which is subject to the air pressure in chamber 46A and piping 42. Valves 43, 44 define chamber 46B to which there is fluid access via pipe A. An accelerator device for 40 comprises chamber 50 in which ball valve 51 normally closes outlet pipe A against the passage of air into chamber 46B. Ball valve 51 includes ball cage 53 retained over ball stem 52 by pivoted weight 56. Pressurised air is fed to chamber 50 by pipe B also coupled to chamber 46A. The air pressure in piping 42 is sensed by branch pipe C connected to pipe B and coupled to one side of differential pressure chamber 60. 60 is comprised of chambers 60A, 60B separated by piston 61 spring biased at 62, oil or hydraulic fluid being supplied by pipe network 64 to chamber 60A. Chamber 60A is coupled via restriction 65 to accumulator 70 comprising spring-biased piston 71 movable between air-filled lower portion 72A at 1 atm. and hydraulic fluid-filled upper portion 72B. Air escapes from 72A via orifice 74. Accumulator 70 is also coupled to differential pipe valve actuator 80 which comprises piston 81 slidable in chamber 82 in engagement with rod 83 which abuts pivoted weight 56 in chamber 50, chambers 82 and 50 being isolated by sealing "O" ring on rod 83. Hydraulic fluid is supplied to the rod side of piston 81 by the portion of piping 64 coupled to differential chamber 60A. On activation of sprinkler head 47, the reduced air pressure causes piston 61 to fall, thereby reducing the hydraulic fluid pressure on the left of piston 81. Since the fluid on accumulator 70 side of restrictor 65 bleeds slowly the hydraulic fluid pressure urges 81 to the left, engaging rod 83 with weight 56 and thereby opening ball valve 51. Valve 43 thus opens to the passage of water from 41. In the Fig. 3 embodiment, when a sprinkler opens the air-pressure on both sides of valve 44 is equalised to 1 atm. by venting pipe A to atmosphere. In Fig. 4 pipe A is coupled directly to water main 41 and a pipe D interconnects chambers 46B and 50.