GB2160182A

GB2160182A - Liquid supply apparatus

Info

Publication number: GB2160182A
Application number: GB08414848A
Authority: GB
Inventors: Edward Albert Skinner
Original assignee: Elopak Ltd
Current assignee: Elopak Ltd
Priority date: 1984-06-11
Filing date: 1984-06-11
Publication date: 1985-12-18
Also published as: GB8414848D0

Abstract

An apparatus for supplying liquid (20) intermittently and substantially without drips comprises a valve (2, 3) operably intermittently to allow dosages of the liquid (20) to flow from the valve (2, 3), ducting (5) extending downwardly to the valve (2, 3) for leading the liquid (20), thereto, and a vacuum pump arranged to produce suction in the ducting (5) in order to reduce the hydrostatic pressure which the liquid (20) would otherwise produce at the valve (2, 3). The apparatus may form part of a system for producing milk or other liquid-filled cartons. <IMAGE>

Description

SPECIFICATION Apparatus According to one aspect of the present invention, there is provided apparatus for supplying liquid intermittently, comprising valve means operable intermittently to allow dosages of said liquid to flow from said valve means, ducting extending downwardly to said valve means for leading said liquid to said valve means, and suction-producing means arranged to produce suction in said ducting in order to reduce the hydrostatic pressure which said liquid would otherwise produce at said valve means.

According to another aspect of the present invention, there is provided a method of supplying liquid intermittently, comprising causing liquid to flow downwardly to valve means, operating said valve means intermittently to cause dosages of liquid to flow therefrom, and producing suction on said liquid in order to reduce the pressure of said liquid at said valve means.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawing, which shows diagrammatically a filling system for filling cartons with liquid.

The system shown in the drawing is part of a machine for producing liquid-filled cartons, for example milk-filled cartons. The cartons are advanced beneath a vertical filling nozzle 1 which may be one of a row of such nozzles and which contains a valve closure member 2 urged upwardly to seal against an annular valve seat 3 of the nozzle 1 by a compression spring 4 acting between the valve closure member 2 and the nozzle 1. The nozzle 1 communicates with a vertical cylinder 5 containing a vertical filling piston 6 and formed internally with an annular valve seat 7. A valve closure member 8 is arranged to seal against the seat 7 under the action of a compression spring 9. The cylinder 5 may be one of a row of such cylinders opening at their upper ends into a liquid-containing tank 10 provided with a liquid inlet 11 and closed by a lid 12. The system as so far described is conventional.

However, the underside of the lid 12 communicates via tubing 13 and a sight bowl 14 with a vacuum pump (not shown). Communicating with the tubing 13 between the lid 12 and the bowl 14 is a positive pressure relief vaive 15 and also a negative pressure relief valve 16 upstream of which is an air filter 17. Mounted in the lid 12 is a vacuum gauge 18 to measure the vacuum created by the vacuum pump in the space 19 above the uppermost surface of the liquid 20 in the tank 10. A bore 21 is formed through the member 8 in order to allow the suction effect of the vacuum to be propagated through to the nozzle 1 even when the member 8 is closed.

The production of a vacuum in the tank 10 counteracts, at least partly, the hydrostatic pressure which the liquid 20 would otherwise produce at the valve 2, 3, and this has two advantages, which are firstly of reducing, at least partly, the tendency for dripping of liquid from the valve 2, 3 and, secondly, of enabling the return spring 4 to be weaker than otherwise so that the opening pressure of the valve 2, 3 can be reduced, so reducing the velocity of liquid from the valve 2, 3 and thus reducing foaming in the case of a liquid such as milk which is prone to foaming. These advantages are particularly noticeable in filling system in which the valves are hydrostatically operated, for example the system shown.The vacuum maintained in the space 19 is advantageously of such a value that, with the member 2 closed and the filling piston 6 stationary, there is a very slight upward force upon the member 2 additional to the upward force produced by the return spring 4. It is thus practically true to say that the spring 4 has to overcome only the weight of the valve closure member 2, the weight of the liquid 20 being counteracted by the effect of the pressure differential between the vacuum in the space 19 and atmospheric pressure. In other words, atmospheric pressure holds the member 2 closed when the desired vacuum is being maintained in the space 19. When the piston 6 moves downwards, it draws liquid from the tank 10 through the bore 21 and past the open member 8, suction of course being maintained at the valve 2,3.When the piston is stationary, the suction is maintained at the valve 2,3 owing to the presence of the bore 21. During the filling stroke of the piston 6, when the piston 6 travels up the cylinder 5, it pressurises the liquid until the effect of the vacuum is overcome, whereupon the valve 2,3 opens and allows the liquid to flow into the carton. When the piston reaches its upper end position, the member 2 closes under the pressure of the return spring 4 and the suction is again created there through the bore 21, so holding the member 2 shut. The negative pressure relief valve 16 serves to maintain a substantially constant value of vacuum, for example 5" Hg, whilst the positive pressure relief valve 15 gives a quick exhaust facility during the initial filling of the empty tank 10 through the inlet 11.

To set up the system for operation, the vacuum pump is switched on and this induces a vacuum in the empty tank 10. The liquid is now allowed to enter the tank 10 through a level-control valve (not shown) in the inlet 11. Since the air being expelled by the incoming liquid is normally greater in volume than the vacuum pump can handle, this excess air escapes through the valve 15. When the correct liquid level has been reached in the tank 10, the valve 15 closes under the action of its spring and the vacuum will build up in the space 19 until the desired vacuum is registered on the gauge 18. Thereafter, the valve 16 will open to prevent the vacuum from becoming greater than the desired value in the space 19, the filtered air entering through the valve 16 passing through the vacuum pump other than via the space 19.

Since with a liquid such as milk, foam from a processing plant upstream of the inlet 11 can build up relatively easily in the space 19 and the tubing 13, and it is undesirable in any case that this should reach the vacuum pump, the sight bowl 14 is provided to give the operator a visual indication of any excessive amount of foam building up.

With the filling piston 6 stopped and the vacuum pump operative, the correct vacuum is maintained in the space 19 by the vacuum pump drawing filtered air through the valve 16, the valve 15 remaining closed and the valve 2,3 being drip-free.

With the filling piston 6 operative as well as the vacuum pump, when the liquid-level control valve opens to allow replacement liquid into the tank 10, the valve 16 partially closes, so reducing the volume rate of air flowing through it to the tubing 13, and thus allowing the correct vacuum to be restored.

Claims

1. Apparatus for supplying liquid intermittently, comprising valve means operable intermittently to allow dosages of said liquid to flow from said valve means, ducting extending downwardly to said valve means for leading said liquid to said valve means, and suction-producing means arranged to produce suction in said ducting in order to reduce the hydrostatic pressure which said liquid would otherwise produce at said valve means.

2. Apparatus as claimed in claim 1, and further comprising a reservoir connected upstream of said ducting, said suction-producing means being arranged to produce suction continuously in a space above said liquid in said reservoir.

3. Apparatus as claimed in claim 2, and further comprising a negative pressure relief valve communicating with said space.

4. Apparatus as claimed in claim 2 or 3, and further comprising a positive pressure relief valve communicating with said space.

5. Apparatus as claimed in claim 2, 3 or 4, and further comprising a sight bowl by way of which said suction- producing means communicates with said space.

6. Apparatus as claimed in any preceding claim, wherein said apparatus further comprises a first valve provided with a bleed whereby suction can be propagated from upstream of said first valve to downstream thereof, and said valve means comprises a second valve connected to the downstream end of said ducting.

7. Apparatus as claimed in claim 6, and further comprising pumping means connected to said ducting at a location between said first valve and said second valve.

8. A filling system for filling cartons with liquid and comprising an apparatus as claimed in any preceding claim.

9. A method of supplying liquid intermittently, comprising causing liquid to flow downwardly to valve means, operating said valve means intermittently to cause dosages of liquid to flow therefrom, and producing suction on said liquid in order to reduce the pressure of said liquid at said valve means.

10. A method as claimed in claim 9, and further comprising producing suction continuously in a space above said liquid in a reservoir.

11. A method as claimed in claim 10, and further comprising maintaining said suction in said space at a substantially constant value.

12. A method as claimed in any preceding claim, and serving to fill cartons with liquid.

13. A method of, or apparatus for, supplying liquid intermittently, substantially as hereinbefore described with reference to the accompanying drawings.