Apparatus for filling containers with liquid

#This invention relates to improved apparatus for filling containers with quantities of liquid. While not limited thereto the apparatus has particular application to the filling of containers with agents which are dangerous from toxic or other effects and to filling processes which are carried out under sterile operating conditions.

#Hitherto it has been the practice to first fill containers by a constant depth method of filling and thereafter to inspect and test each container by a constant depth gauge or where highly toxic agents are being filled by electronic or other devices.

#One object of the present invention is to provide an improved form of filling apparatus in which the filling and inspection processes are carried out simultaneously and in which a record of the filling operation on each container is retained.

#The invention will be described by way of example with reference to the accompanying drawings in which

#FIG. 1 shows diagrammatically the filling apparatus of the present invention.

#FIGS. 2A - 2H illustrated the respective positions of the filling nozzle head and the flow of fluids into the container.

#Referring now to FIG. 1, the filling head 1 comprises two parallel nozzles 2 and 3 fixedly positioned in relation to one another and attached to flexible connecting tubes 4 and 5 respectively. These parallel nozzles 2 and 3 are joined together so as to terminate in an oblique pointed extremity and enclose between them a channelled air bleed 6 communicating with the atmosphere or with a sterile air supply under substantially atmospheric pressure at its upper end and extending down to an orifice situated in the lower wall of the nozzle combination. The connecting tube 4 is led down within a liquid reservoir 7 and terminates in a dip pipe 8. The other tube 5 is flexibly connected to a control chamber 9 which itself is connected by a tube 10, through a restrictor 11, to a controlled vacuum separator 12 connected to a vacuum pump (not shown) so that the air in the connecting tube 5 is always at a pressure lower than atmospheric. The filling head 1 is positioned at a higher level than both the liquid reservoir 7 and the controlled vacuum separator 12 so that gravity drainage ensues from the pipes 4 and 5 to the reservoir 7 and separator 12 respectively. Near the top of the delivery tube 4 a further flexible pipe 13 is connected to a valve unit 14 controlling a supply of gas at or above atmospheric pressure. This valve unit 14 is normally closed by a poppet valve 16 retained against a seat 15 by a compression spring 17 supported by the top of the valve casing and which is coaxial with the valve stem so that the spring 17 is free to expand or to contract to follow any corresponding movement of the poppet valve 16. A contacting arm 18 is rigidly attached to the stem of the poppet valve 16 to operate a normally closed switch 19 placed in series with an electro-hydraulic thrustor 20 and a press-button resetting switch 21. The thrustor 20 operates on an arm 51 which supports the filling head 1 and which is balanced about a fulcrum 52 by a counterpoised weight 53. The valve stem 16 passes into a diaphragmed vessel 22 and is connected to a diaphragm 23 which partitions off an air chamber 24. This air chamber 24 is connected by means of a delivery tube 25 to a source of air pressure and is also connected by means of a second tube 26 to an air nozzle 27 which extends through a base portion 28 of a modified Kelvin coupling 29. A balanced arm 30 of the coupling is hinged about a fulcrum 31 and, after tilting, either rests on an adjustable stop 32 on one side of the fulcrum or in contact with the nozzle 27 on the other. An arm 30 of the coupling supports a steelyard 33 which consists of a length of completely sealed tubing which is partially filled with mercury. On the nozzle side of the fulcrum 31 there is an aperture 34 in the balanced arm 30 and through this aperture passes a rod 35 enlarged at is upper end 36 and connected at its lower extremity to a diaphragm 37. This diaphragm is located across the upper portion of the control chamber 9, in the wall of which there is a test cock 38, a pressure gauge 39 and a walled aperture 40. This aperture 40 contains a diaphragm 41 which forms part of a variable condenser 42 included in an oscillating circuit 43 which connects with a pressure variation recording system. In a preferred recording system the oscillating circuit 43 connects with an R.F. amplifier 44 and discriminator 45. The discriminator is joined to a current amplifier 46 which is connected to a recording milliammeter 47.

#Each container 48 to be filled with liquid is mounted on a power operated platform 54 and is provided with an end aperture 49 which is normally sealed by a rubber septum 50.

#In use, a sealed container 48 is positioned below the filling head 1 and on pressing the button resetting switch 21 the electro-hydraulic thrustor 20 rotates the arm 51 and causes the filling head to descend so that the pointed nozzles 2 and 3 are caused to pierce the rubber septum 50 which formerly sealed off the container. The nozzles remain stationary inside the continer provided the thrustor circuit is not broken and in this position the rubber septum grips the nozzles and effectively seals off, as previously, the interior of the container from the atmosphere except for the effect of the air bleed aperture 6. The vacuum pump connected to the controlled vacuum separator 12 is now directly connected to the interior of the container 48 and thus the container 48 is evacuated to an absolute pressure controlled by the size of the air bleed 6. When the reduced pressure in the container is sufficient to overcome the effect of the liquid head liquid is induced through the dip pipe 8, along the connecting tube 4 and down through the nozzle tube 2 into the container 48 and this liquid flow continues so long as the syphon action, now established, is not severed. Any liquid droplets or other liquid carryover which are induced into the vacuum circuit are deposited in the separator 12 and are retained. Liquid now flows freely into the container 48 until the level of the liquid therein rises to cover the bottom of the filling head 1 and thereafter the nozzle 3 becomes filled with liquid due to the reduced pressure in the controlled vacuum separator 12 and the closure of the air bleed aperture 6. This reduced pressure also acts downwardly on the diaphragm 37 connected to the rod 35, and a clock wise moment is imparted to the balanced arm 30 about its fulcrum 31. The sensitivity of the mechanism is such that the suction pressure on the diaphragm 37 is sufficient to tilt the balanced arm 30, which was previously set with an anticlockwise bias, in a clockwise direction before any appreciable quantity of liquid flows along the connecting tube 5. This tilting motion brings the balanced arm 30 to rest on the air nozzle 27 and the corresponding tilt given to the steelyard 33 causes a flow of mercury within it to the air nozzle end of the steelyard thus setting up a substantial turning moment due to the redistribution of the weight of the mercury from the fulcrum 31. This additional clockwise moment assists in effectively sealing the air nozzle 27.