GB2078867A - Metering system for dispensing beer or other potable carbonated liquids - Google Patents

Abstract

Beer is dispensed in metered quantities from a keg 14 through an outlet 9 under the control of a dispensing valve 10 by a membrane metering pump 1. The valve 10 and a gas inlet valve 18, which supplies gas to the pump 1, are controlled by an electrical controller 22, a dispensing operation between triggered by closing a press button switch 24. The controller 22 is also actuated by a reed switch 26, which is controlled by a magnetic closure member 27 of an inlet non-return valve 12 and the reed switch 26 and the controller 22 control the valves in such a way that after a measured volume of beer or other liquid has been dispensed from the compartment 4 of the pump 1 and the compartment 4 has been refilled with beer, the valve 18 is opened whilst the dispensing valve 10 remains closed so that the beer in the compartment 4 and in the ducts leading from the compartment 4 to the valve 10 is maintained under the pressure of the gas supplied through the valve 18. <IMAGE>

Description

SPECIFICATION Metering system for dispensing beer or other potable carbonated liquids This invention relates to metering systems for dispensing measured volumes of potable carbonated liquids. Whilst such systems can be used for dispensing soft carbonated drinks, their primary purpose is for dispensing beer in Public Houses and bars and the invention will be described in this context.

One kind of system forthis purpose comprises a gas-pressure operated metering pump having a chamber with a partition which is movable to and fro between two end positions in the chamber and divides the chamber into a metering and pumping compartment on one side of the partition and a gas pressure compartment on the other side of the partition, the metering and pumping compartment being connected buy a ductthrough an outlet nonreturn valve to an electrically operated dispense valve and through an inlet non-return valve to an inlet for liquid under pressure, and the gas pressure compartment being connected to a compressed gas inlet through an electrically operated gas inlet valve and to a vent valve, the electrically operated valves being controlled by a manually operated switch and an electrical controller in such a way that when the partition is in one end position and the metering and pumping compartment is full of liquid, the dispense valve is opened and gas under pressure is admitted to the gas pressure compartment to move the partition to the second end position and dispense a measured volume of liquid through the dispense valve, after which the dispense valve and the gas inlet valve are closed and the vent valve is opened so that liquid under pressure flows into the metering and pumping compartment and returns the partition to the first end position.

In existing systems of this kind, when the partition has returned to the first end position, the gas inlet valve is closed and the vent valve is open so that the liquid in the metering and pumping chamber and between this chamber and the dispense valve is under only a small pressure applied to it through the liquid inlet which is itself under pressure. Since the metering pump itself is generally fitted in a cellar adjacent a keg holding the carbonated liquid, the pressure in the metering and pumping chamber is sufficient to hold the carbon dioxide in solution in the liquid, but commonly there is a long length of piping between the outlet non-return valve and the dispense valve and this commonly leads upwards to a bar so that the pressure of the liquid in this piping gradually decreases.When the system is used for dispensing lager or other highly carbonated beers or other liquids, the pressure in the outlet piping or other ducting upstream of the dispense valve may fall below the carbonation equilibrium pressure of the liquid and substantial fobbing then takes place.

This gives rise to great difficulty when the next measure of liquid is to be dispensed because a great deal of fob tends to be dispensed with the liquid.

Systems of the kind described have now been used for dispensing lager for some years and yet the problem of fobbing in the outlet piping or other ducting has not previously been satisfactorily overcome.

According to this invention, in a system of the kind described, the electrical controller is arranged to cause the gas inlet valve to be opened and to remain open and the vent valve to be closed and to remain closed after the partition has returned to the first end position and the dispense valve has closed so that, in operation, the liquid in the metering and pumping chamber and hence in the ducting between the metering and pumping chamber and the dispense valve is kept subjected to the pressure of the compressed gas.

In practice, the pressure of the compressed gas is made such that at the highest point in the duct between the metering and pumping chamber and the dispense valve, the pressure of the liquid is still above the carbonation equilibrium pressure so that no fobbing occurs.

If any small amount of fob is produced in the period, which may be very short indeed, between the return of the partition to the first end position and the closing of the dispense valve, while the vent valve is still open, and the subsequent closure of the vent valve and re-opening of the gas inlet valve, this does not matter because the fob will disappear again as the carbon dioxide is forced back into solution upon re-pressurisation of the liquid in the duct.

A restriction is still preferably provided close to the dispensing outlet at the dispense valve, but this restriction needs only to be sufficient to maintain the pressure of the lager or other liquid above the carbonation equilibrium pressure during dispensing and to provide the desired speed of dispensation.

In spite of its apparent simplicity, the present invention has been found to overcome the problem of fobbing of lager and other highly carbonated beers when these are dispensed through systems of the kind described. This problem has existed for some years and the present invention fulfils a very real need which has not previously been satisfied.

An example of a metering system in accordance with the invention will now be described with reference to the accomanying drawing which is a diagram showing, highly diagrammatically, the pump and the various valves and both the liquid and electrical connections of the system.

In the example illustrated, a gas-pressure operated metering pump 1 has a housing 2 which is divided by a partition in the form of a flexible membrane 3 into a pumping and metering compartment 4 and a gas pressure compartment 5. The membrane 3 is shown in a mid-position, and it is movable between a first end position in contact with the bottom of the housing 2, in which the compartment 4 is at its maximum volume and is filled with liquid and an upwardly bowed second end position in contact with the top of the housing 2, in which the volume of the compartment 4 is reduced substantially to zero. The volume swept by the membrane 3 between the two end positions is of a predetermined magnitude, which is usually one half pint.

The compartment 4 is connected by piping 5' and 6 to an outlet non-return valve 7 and thence through further piping 8 to a dispensing outlet 9 fitted with a solenoid-operated dispense valve 10.

The piping 5' also leads through further piping 11 to an inlet non-return valve 12 and thence through piping 13 to a beer keg 14 which has a connection 15 through which carbon dioxide under pressure is applied to the surface of the beer in the keg.

The compartment 5 is connected through piping 16 and 17 to a compressed air inlet solenoidoperated valve 18 which leads to an inlet 19 for compressed air. The piping 16 also leads through further piping 20 to a venting valve 21. As a modification of this example, the valve 18 may be a three-way solenoid valve, one of the ports of which leads to the atmosphere so that the valve acts as both a compressed air inlet valve and a venting valve.

An electronic controller 22 is connected by a lead 23 to a push-button switch 24 and through a lead 25 to a reed switch 26. The reed switch 26 is operated by a closure member 27, which is magnetic, of the inlet non-return valve. The electronic controller 22 is also connected, by leads which are not shown, to the valves 10,18 and 21.

Underthe normal conditions obtaining inbetween the dispensing of measured volumes of beer from the outlet 9, the electronic controller 22 causes the dispense valve 10 and the venting valve 21 to be closed and the compressed air supply valve 18 to be open. Thus the compartment 5 is pressurised by the compressed air and the beer in the compartment 4 is under the same pressure. The beer in the piping 5', 6,8 and 11 is also maintained under pressure although the pressure in the piping 8 will decrease towards the valve 10 owing to the pressure head of the beer within it. Nevertheless the pressures in the compartments 5 and 4 are such that the pressure immediately upstream of the valve 10, when the valve 10 is closed, is above the carbonation equilibrium pressure of the beer, which may for example be lager, from the keg 14.In consequence there is no fobbing in any of the piping.

In order to dispense a measured quantity, for example one half pint, of beer from the outlet 9, the push-button switch 24 is closed. This causes the controller 22 to open the valve 10 and thus the air under pressure in the compartment 5 pushes the flexible membrane 3 upwards into its upwardly bowed second end position and forces beer from the compartment4throughthe piping 5' and 6, the non-return valve 7, the piping 8 and the valve 10 from the outlet 9.The pressure of the beer in the piping 6 and 11 at this time holds the non-return valve 12 closed so that the closure member 27 is kept adjacent the reed switch 26; this closes the reed switch 26 and maintains a hold-on circuit in the controller 22 which causes the controller 22 to keep the valve 10 open even if the push-button switch 24 is released while the measure of beer is being dispensed. Accordingly once the push-button switch 24 has been closed, a full measure of beer is necessarily dispensed.

When the membrane 3 reaches its upwardly bowed second end position, there is a momentary drop of pressure in the remaining part of the compartment 4 and in the piping downstream of this compartment as the membrane 3 isolates the inlet two the piping 5' from the pressure of the compressed air. This momentary drop in pressure causes the closure member 27 of the non-return valve 12 to open and as the closure member 27 rises in opening, the magnetic field which was influencing the reed switch 26 is removed or decreased so that the reed switch 26 opens. The opening of the reed switch 26 causes the controller 22 to shut the dispense valve 10 and the compressed air supply valve 18 and to open the venting valve 21.Owing to the reduction in pressure in the compartment 5, beer is forced by the carbon dioxide pressure in the keg 14 through the pipe 13 and the inlet non-return valve 12 through the pipe 5' to refill the compartment 4 and return the membrane 3 to its first end position as shown in the drawing. During this time the closure member 27 remains in its upwardly moved position so that the reed switch 26 remains open. During this time there is not of course any flow through the piping 6 and 8 and the non-return valve 7 because the valve 10 is closed.

When flow into the compartment 4 ceases because the membrane 3 has reached its first end position, the closure member 27 in the valve 12 falls again and so causes the reed switch 26 to be closed.

This causes the controller 22 to close the venting valve 21 and open the compressed air supply valve 18 so that the beer in the compartment 4 and the piping downstream of this compartment is again pressurised by the compressed air.

Claims (6)

1. A metering system for dispensing measured volumes of potable carbonated liquid, the system comprising a gas-pressure operated metering pump having a chamber with a partition which is movable to and fro between two end positions in the chamber and divides the chamber into a metering and pumping compartment on one side ofthe partition and a gas-pressure compartment on the other side of the partition, the metering and pumping compartment being connected by a duct through an outlet non-return valve to an electrically operated dispense valve and through an inlet non-return valve to an inlet for liquid under pressure, and the gas-pressure compartment being connected to a compressed gas inlet through an electrically operated gas inlet valve and to a vent valve, the electrically operated valves' being controlled by a manually operated switch and an electrical controller in such a way that when the partition is in one end position and the metering and pumping compartment is full of liquid, the dispense valve is opened and gas under pressure is admitted to the gas pressure compartment to move the partition to the second end position and dispense a measured volume of liquid through the dispense valve, after which the dispense valve and the gas inlet valve are closed and the vent valve is opened so that liquid under pressure flows into the metering and pumping compartment and returns the partition to the first end position, wherein the electrical controller is arranged to cause the gas inlet valve to be opened and to remain open and the vent valve to be closed and to remain closed after the partition has returned to the first end position and the dispense valve has closed so that, in operation, the liquid in the metering and pumping compartment and hence in the duct between the metering and pumping compartment and the dispensing valve is kept subjected to the pressure of the compressed gas.

2. A system according to Claim 1 in which a restriction is provided in the duct close to a dispensing outlet at the dispense valve, the restriction being sufficiently small to maintain the pressure of liquid being dispensed above the carbonation equilibrium pressure during dispensing.

3. A system according to Claim 1 or Claim 2, in which the partition is in the form of a flexible membrane which extends across a housing in which the chamber is situated.

4. A system according to any one of Claims 1 to 3, in which the dispense valve and the gas inlet valve are solenoid-operated.

5. A system according to any one of the preceding Claims, in which the inlet non-return valve has a magnetic closure member, and a reed switch, which is connected to the electrical controller, is mounted adjacent the inlet non-return valve in a position such that the switch is closed when the non-return valve is closed and closure of the switch causes the control ler to hold the dispense valve open during the whole of the time that liquid is being dispensed from the metering and pumping compartment and to open the gas inlet valve and close the vent valve when the partition returns to the first end position and liquid flow into the metering and pumping compartment ceases.

6. Asystem according to Claim 1, substantially as described with reference to the accompanying drawing.