GB1145727A - Alarm systems - Google Patents

Abstract

1,145,727. Fluid control alarm system. IMPERIAL-RIV, S.r.L. 5 June, 1967 [6 June, 1966], No. 25869/67. Heading G4F. [Also in Division G3] A fluid circuit operated alarm system provides concurrent audible and intermittent visual alarms which when acknowledged become a steady visual alarm and the fluid circuit includes a recycling amplifier controlled through a pipe in such a way that when the remote end of the pipe is closed the amplifier oscillates to produce an intermittent control for the visual alarm. The fluid system of Fig. 2 comprises two coincidence elements 37, 38 in which fluid flows to branches 42 and 47, respectively, only when fluid is coincidentally applied to 40, 41 or 45, 62 and a bi-stable element 39 in which the fluid from 50 stably flows to branch 51 or 52 once momentarily deflected by fluid in control branches 53 and 54. It also comprises a recycling amplifier 3 in which fluid from 12 divides between branches 13 and 15 according to the flow in 14, that in 15 being recycled to a control channel 17 to cause the amplifier to operate as a trigger switch. In operation, the alarm condition produces fluid flow into pipe 58 which, reacting with flow into pipe 41 produces flow to 42. Part of this operates a horn 36 and part flows via 59 and 26 to depress the membrane of a valve 25 and close aperture 28. A pulse is thus set up at the input of amplifier 3 and this travels back along the pipe to the membrane where it is reflected back to the input of the amplifier to trigger a further pulse. The amplifier thus oscillates and the resulting pulses in output branch 15 operate the switch of an electric flasher or an equivalent curtain type non-electric indicator. The fault is acknowledged by momentarily opening valve 63 to allow incoming fluid to react with fluid previously flowing through 45 to outlet 49, so as to provide a momentary flow in 53. This directs flow from 45 to the other branch, i.e. to 52. Cessation of flow in 51 reacts in the coincidence circuit 37 to terminate the flow to the horn and the transfer of the flow to 52 opens valve 25, the flow continuing to the amplifier where it maintains a steady indication from the visual indicator (terminating the flashing). The alarm is reset by momentarily opening valves 65 thus restoring flow in the bi-stable element to the original left-hand branch 51, releasing the visual indicator. The acknowledgment and resetting valves may be common to a number of units. Fig. 1 (not shown) illustrates a simplified system in which acknowledgment is effected by opening a valve (22) individual to the element and resetting is effected by reclosing the valve. In Fig. 3 (not shown) the coincidence circuit 37 is replaced by a bi-stable element (2) so that the audible and visual alarms persist if the control signals are of pulsating type. Several alarm circuits may be secured together as layers and a common acknowledgment and reset layer provided (Fig. 4, not shown).