GB829184A - Improvements in or relating to indicators for fire extinguishers and like liquid spraying apparatus - Google Patents

Abstract

829,184. Fire extinguishers. NATIONAL RESEARCH DEVELOPMENT CORPORATION. March 7, 1956 [March 7, 19551, No. 6596/55. Class 47 [Also in Groups XVIII and XXVIII] An indicating device for a spraying apparatus in which liquid is discharged from a container under pressure, consisting of a unitary structure which includes a gas pressure indicating member and a float, the position of the gas pressure indicator being controlled by the gas pressure in the container and the float serving to indicate the quantity of liquid in the container. In a fire extinguisher having a closure member 3, a valve 13 secured to a tube 9 is normally held upon its seat 14 by gas pressure within the flask assisted by the pressure of a light spring 18 on one side of a plate 16 attached to the tube 9 and opposed by a stronger spring 17 on the other side of the plate 16, the arrangement being such that in response to a reduction in pressure in the flask due to leakage of gas the valve 13 and the tube 9 are moved downwardly by the spring 17 so that an enlarged head 19 of the tube 9 occupies a position below a guard member 21 to serve as a visual indication of loss of pressure. Within the tube 9 is provided a float 20 which can be observed through a transparent part of the tube 9 at its upper end. In the event of leakage of liquid the float 20 sinks and is no longer visible. The tube 9 is provided with holes 27, 28, whereby when the tube moves to its depressed position in response to leakage of gas, the lower hole 27 moves into the upper part of the flask which is thereby placed in free communication with the atmosphere. In order to operate the extinguisher, the guard 21 is pivoted to the side (Fig. 4) so that a slot 22 in the guard embraces the tube 9. The tube 9 is then manually depressed to open the valve 13, its downward movement being limited by engagement of the head 19 with the sides of the slot 22 so that the hole 27 does not move into the flask. The liquid is then forced up the tube 9 past the valve 13 and through the nozzle 26. Due to fall in pressure in the flask upon discharge, the spring, 17 maintains the valve 13 open without further manual assistance. The head of the tube, or the float, may be used to control an indicating disc or the like. When charging the flask the closure member 3 is fitted after the liquid has been introduced and a cap 15 on the closure member is moved into an upper position in which the pressure on the spring 17 is relieved while gas is introduced through the nozzle 26 until a pressure has been built up in the flask enabling the cap 15 to be moved into its lower position.