GB1291918A - Improvements in and relating to valves for aerosol containers - Google Patents

Abstract

1291918 Valve for dispenser INSTITUTE FOR INDUSTRIAL RESEARCH & STANDARDS and N J THOMPSON 9 July 1970 [10 July 1969] 33414/70 Heading F1R [Also in Division B8] A valve for a dispenser for pressurized fluids comprises a permeable membrane 13 and means responsive to the pressure of vapour that has diffused through the membrane to open the valve. The valve is used in a dispenser which can be set to deliver a metered quantity of fluid automatically at regular intervals for such purposes as insecticidal control in kitchens and food stores, deodorizing lavatories, or lubricating machinery. Vapour passes from the dispenser via channel 11a, diffuses through the membrane 13 and porous paper 14 via channel 40 to timing chamber 28, thereby raising flexible diaphragm 29 from the position illustrated in Fig. 1 (not shown) to that in Fig.2. This raises cradle 49 against coil spring 51, thereby tending to raise snap spring 48, the centre of which is restrained against upward movement by finger 60. Spring 48 snaps over into the position shown in Fig.2, thereby depressing collar 46 which is fast with tube 41, thus depressing sealing cup 19 which is within metering chamber 18. This chamber is initially filled with fluid from the dispenser via dip tube 15 and the outlet of the chamber is closed by the cup 19 being held against seal 20 by spring 25, but on depression of the cup by the action of the snap spring the outlet is opened, the inlet 21 is sealed and the contents of the chamber are expelled through orifice 43 via the tube 41. The resultant evacuation of the chamber 18 deforms the seal 20 so that the pressure inside chamber 28 is released and the cycle recommenced. The finger 60 forms part of an actuator 53 which is provided with ribs 57 which, in the position for automatic operation as already described, abut cover 54. If the actuator is rotated through a quarter-turn the ribs recede into slots (59), Fig. 3 (not shown), in the cover, so that the finger 60 is withdrawn upwards Fig. 4 (not shown), away from the snap spring 48, so that the chamber 28 may expand without operating the valve. In either position the valve may be operated manually by pressing button 42. If this button is depressed as far as possible the inlet 21 of the metering chamber 18 is closed and the contents of the chamber expelled; lesser pressure opens the outlet without sealing the inlet and allows a continuous expulsion of fluid from the dispenser via the chamber 18. In a modification Fig. 5 (not shown) the plane membrane 13 beneath member 11 is replaced by a membrane (113) of cylindrical form around a member (111). Coil spring 51 is replaceable by a stack of disc springs (151). These may be bimetallic so that the thrust against the cradle (149) increases with increasing temperature thereby counteracting the increased rate of diffusion through the membrane with increased temperature, thus tending to maintain the period of the automatic dispensing cycle constant. On the other hand, an increasing frequency of discharge with increasing temperature may sometimes be desirable, for example when used for insecticidal or deodorizing purposes.