GB1279388A - Fire protection system - Google Patents

Abstract

1279388 Automatic fixed fire-fighting installation FACTORY MUTUAL RESEARCH CORP 8 Oct 1970 [8 Oct 1969 (2) 16 Dec 1969 15 Sept 1970] 47890/70 Heading A5A An automatic fixed fire extinguishing system comprises a plurality of discharge heads each supplied with extinguishant from delivery means, automatic fire-responsive means for actuating the heads in a sequence dictated by information received from the fire, and control means which reduce the number of heads which will be opened to deliver extinguishant as compared to the number which would be automatically actuated in the absence of the control means. A system for protecting a large area containing combustible materials or fuel comprises a plurality of branch lines supported at an elevated position over said area and supplied with extinguishant from a common source, each of said branch lines having a plurality of discharge heads connected thereto, and means associated with the discharge heads for selectively opening them in a logical sequence dictated by information received from a fire, each of said heads being arranged and constructed to deliver a downward spray of extinguishant at a predetermined spray angle, and said heads being so spaced that the extinguishant therefrom will not wet the opening means to alter the logical sequence of opening. The number of heads actuated may be limited by (i) establishing a pressure threshold so that a minimum pressure must exist at each head before it will open or (ii) moving small heat shields into position over the thermal fuses of the remaining heads after one has been actuated. In the nozzle head of Fig. 3 water outlet 43 is normally closed by piston head 38 on slidable rod 36, the latter being latched in position by the end of slidable rod 44 extending through boss 46. Thermal fuse 56 engages with the other end of rod 44, and piston head 58 is mounted on the rod and spring-biassed to the left. Passage 62 between the interior of valve body 26 and the space to the left of piston 58 allows the system water pressure to urge 58 to the right against the spring action. On fusion of element 56 the system pressure, if sufficient, drives rod 44 to the right, thus releasing rod 36 which is expelled from the nozzle to allow water through outlet 43. If insufficient water pressure exists, the action of spring 60 prevents the release of rod and piston 36, 38 even on fusion of 56. Fig. 8 shows a further nozzle head embodying a pressurised bellows assembly (206) which regulates the extinguishant flow rate according to the pressure prevailing, and prevents flow below a predetermined minimum pressure, and Fig. 12 a similar nozzle head to Fig. 8 with the addition of a pressure actuated heat shield (348). The extinguishant may be water or an ablative gel.