Patent GB-1392240-A (GB)
Title: Safety head arrangement for fire extinguishers
IPC: F17C7/00
Filed: 1972-11-10
Abstract: 1392240 Portable pressurised fire extinguishers WALTER KIDDE & CO INC 10 Nov 1972 [10 Nov 1971] 52164/72 Heading A5A A pressurised fire extinguisher comprises container 11 closed by control head 13 which is movable between outer and inner positions - sealing and venting the container respectively and is interlocked with the container by means of a bayonet type connection including at least one inwardly extending flange 54 on the container and at least one outwardly extending flange-56 on the control head, the latter having raised portion 59 which, on engagement with shoulder 61 of flange 54, constrains the control head in its outer operational position against movement relative to the container. Container 11, e.g. of stainless steel or plas tics material, has neck opening 12a in which is inserted control head 13, e.g. of polymerised formaldehyde, O-ring 14 forming a fluid-tight seal therebetween. Siphon tube 18 extends downwardly from bore 21 in head 13 into container 11 where the extinguishant, e.g. powder is stored. At the upper end of 21 is formed inwardly tapering wall 22 to act as a seat for head 31 of valve member 29, and above 22 narrower bore 23 leads to outlet 46 of head 13. Also in communication with bore 23 is bore 26 stepped at 27 and 28 and housing stem 32 of valve 29. The extending end of 32 is depressed by lever 41 when the latter is squeezed with handle 43. Handle 43 is provided with integral annular support 51 which encircles neck 12 and has at its upper periphery sector-shaped, laterally inwardly protruding lips 54 each formed with flat lateral abutment surface 55 at its lower extremity. Control head 13 is formed with sector-shaped laterally outwardly extending flanges 56, each provided with flat lateral abutment surface 56a at its upper extremity engageable with surface 55 when head 13 is in its operating position. The dimensions are such that head 13 rotates freely within the space enclosed by support 51. Each of peripheral spaces 50 between lips 54 of 51 is preferably defined by a sector angle greater than that of flanges 56 to enable easy insertion or removal of head 13 from opening 16 when flanges 56 are not aligned with lips 54. As shown in Figs 2, 3, each flange 56 has raised stop end 59 with abutment surface 60 transverse to surfaces 56a and engageable with shoulder 61 formed at one end of each of lips 54, such that rotation of head 13 in either direction when in its operational position is prevented by engagement of stops 59 with shoulders 61. Alternatively lips 54 may be apertured or recessed to receive projections on flanges 56. Figs 1-3 show the upper, operational position of head 13 in which the abutting surfaces of 56 and 54 are engaged. The internal pressure within 11 acts to press these surfaces together and rotational movement of 13 is prevented as indicated. Head 13 is removable from 11 by a bayonet action in which the tops of stops 59 are depressed below lips 54 and the head is rotated by 90 to move flanges 56 out of alignment with lips 54. The reverse process is applied to lock the head to the container. The arrangement operates as a safety feature to vent fluid to the atmosphere before head 13 is removed or to indicate that the level of fluid or pressure is too high to allow its safe removal. On depression of 13 sufficient to disengage stops 59 from lips 54, O-ring seal 14 is disengaged from surface 16 and the internal pressure is released. If a substantial force is required to depress 13 the operator will operate valve 29 to disengage the unit before attemping to disassemble the extinguisher.