GB2242181A

GB2242181A - A fluid dosing and mixing system, e.g. for cleaning beer lines

Info

Publication number: GB2242181A
Application number: GB9006185A
Authority: GB
Inventors: Sammy James Engineer; Stephen Charles Lord
Original assignee: Whitbread PLC
Current assignee: Whitbread PLC
Priority date: 1990-03-20
Filing date: 1990-03-20
Publication date: 1991-09-25
Anticipated expiration: 2010-03-20
Also published as: GB9006185D0; GB2242181B

Abstract

A fluid dosing and mixing system is described comprising a mains water inlet (1) which supplies water via a non-return valve (2) and flow sensor (3) to a dosing pump (4). Water is mixed in the dosing pump with a detergent solution pumped via a manual change over valve (5) to one branch outlet (6) to a ringmain, the other branch leading to a cask/bucket outlet (7). Detergent is fed to the dosing pump (4) from a container (8) via a non-return valve (9). A control unit (10) operates wash/ rinse cycles for cleaning beer lines while a priming unit (11) operates to prime the dosing pump. The flow sensor (3), wash/rinse control unit (10) and priming unit (11) are all under the control of an electronic unit (12) to control the rate of operation of the dosing pump in proportion to the flow of fluid through the flow sensor (3). <IMAGE>

Description

A FLUID DOSING AMD YISING ;TSTEN This invention relates to a fluid dosing and mixing system more particularly to a detergent dosing system for cleaning beer lines.

In existing beer lines which carry the beer from the cask to a dispensing outlet it is a requirement that the lines be periodically cleaned. This cleaning process includes passing a mixture of water and detergent in each line, allowing the detergent mixture to stand in the lines to soak them clean and passing a water rinse through the lines to remove the dirty detergent mixture.

This cleaning process has the disadvantage that it is time consuming and could be harmful, as the person cleaning the beer lines has to mix the detergent and water in a container and could come into contact with the caustic solution containing 158 sodium hydroxide used as the detergent.

An aim of the present invention is to overcome the above mentioned disadvantage and provide an automatic fluid dosing and mixing system, According to one aspect of the present invention there is provided a fluid dosing and mixing system comprising a dosing pump, a flow sensor in a line to the pump for the supply of a fluid to be mixed, a control for the supply of fluid and an inlet for the supply of the fluid to be metered by the dosing pump wherein an electronic unit controls the rate of operation of the pump in proportion to the flow of fluid through the flow sensor.

Conveniently, the system includes electronic counters connecting the flow sensor and a solenoid of the dosing pump to control the dosing ratio of the mixing system.

According to another aspect of the present invention there is provided a dosing pump for dosing a predetermined volume of fluid to mix with a second fluid comprising a body secured to a solenoid, said body being closed by a cap having a passage for a fluid flowing therethrough, an axial bore in the body connecting with the passage in the cap, a piston operated by the solenoid to reciprocate within the bore to meter a dose of fluid fed to the bore into the passage, and non-return valves located in the fluid flow passage to the bore and between the passage and bore to prevent backs low of the fluid being mixed.

An embodiment of the fluid dosing and mixing system will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a semi-automatic fluid dosing and mixing system according to the invention; Figure 2 is a part-axial cross-section of a dosing pump as shown in Figure 1 on an enlarged scale; Figure 3 is a diagrammatic layout of a solenoid switching transistor and flowmeter signal conditioning circuit; and Figure 4 is a diagram of a fully automatic cleaning system using a microcontroller to process the signal from the flow sensor to operate a series of solenoid valves feeding fluid to beer lines.

The dosing system shown in Figure 1 is used to dose a mixture of detergent and water for cleaning beer lines.

The system comprises a mains water inlet 1 which supplies water via a non-return valve 2 and flow sensor 3 to a dosing pump 4. Water is mixed in the dosing pump with a caustic detergent solution which is pumped via a manual change-over valve 5 to one branch of an outlet 6 to a ringmain (not shown) while the other branch leads to a cask/bucket outlet 7.

Detergent is fed to the dosing pump 4 from a container 8 via a non-return valve 9. The system includes a control 10, which is situated in the vicinity of the bar and operates the wash and rinse cycles for the cleaning fluids while a priming switch 11 leads to and operates to prime the dosing pump 4. The flow sensor 3, wash/rinse control 10 and the priming switch 11 are all under the control of an electronic unit 12 as will be hereinafter described in detail.

The dosing pump 4 is shown on an enlarged scale in Figure 2 and comprises a body 13 bolted to a solenoid 14 by bolts 15. The body 13 is closed by a cap 16 through which passes a passage 17 for the supply of water.

Passing axially of the body 13 is bore 18 in which slides a piston 19 sealed in the bore by an Spring 20.

The piston 19 is reciprocated by a rod 21 and is returned under the action of a return spring 22.

Detergent fluid is fed from the container 8 via the non-return valve 9 to a passage 23 in the pump body which connects with the bore 18.

Connected with the bore 18 is a passage 24 closed by a ball valve 25 held in position by a spring 26 and an 0-ring seal 27. A pin 28 passes from the passage 24 to locate in a hole in the cap 16. The passage 24 is sealed between the body 13 and cap 16 by an 0-ring seal 29.

The parts 26 to 29 form a non-return valve to prevent the water flowing back into the bore 18. A similar non-return valve may be built into the detergent inlet of the passage 23 to replace the non-return valve 9 in the detergent container 8.

The dosing pump 4 operates as follows: The piston 19 returns to the rest position under the action of the spring 22 and the non-return valve 26 to 29 seals the passage 17 from bore 18. As the piston 19 returns detergent is sucked into the inlet 23, the piston 19 advances against the action of the spring 22 and the non-return valve 26 to 29 forces air into the passage 17 in the cap via the non-return valve 26 to 29.

This sequence is repeated until the system is primed so that the detergent inlet 23 and the bore 18 are full of detergent. The above sequence is again repeated forcing a prescribed volume of detergent into the water flowing through the dosing pump with each stroke of the pump.

In the circuit shown in Figure 3, counters are used to divide the signal from the flow sensor at input 36 and monostable 37 gives the required pulse width to the solenoid 14 via a field effect transistor 38. A low frequency oscillator 39 is used to prime the dosing pump and the oscillator feeds a series of signals into the monostable 37 at the maximum pump operation frequency. This allows rapid priming of the dosing pump at a low rate of flow. A display unit incorporates switches with position measuring means 40 and 41 which display the divide ratio in tens and units respectively via gearing devices 42 and 43.

Figure 4 illustrates in diagrammatic form an automatic version of the cleaning system using a microcontroller for processing the fluid dosing ratio and automatically cycle cleaning solution to rinse water through eight beer lines.

The dosing pump 4 is driven by a 12 volt solenoid 14. Detergent is supplied to the pump via the supply line 30 from the tank (similar to that shown in Figures 1 and 2). Water is fed to the dosing pump from a mains water inlet via a non-return valve 2 and a flow sensor 3.

The water is mixed with the detergent in the dosing pump 4 in the required mixture depending on the flow of water through the flow sensor 3.

The mixture of water and detergent passes along the line 31 to a series of eight beer lines to be cleaned via control valves Al to A4 and B1 to B4.

The control of these valves Al to A4 and B1 to B4 is by a microcontroller 35 via switching transistors and a power supply 44 with a series of outputs 32 to the control valves and a series of inputs 33 from the flow meter 3.

The electronic control valves are powered by a 12 volt supply 44 via a series of switching transistors (not shown) and is connected to the micro-controller and display unit 35 by an electric loom 34.

The electronic circuit uses switches to control the divided ratio of flow signal from the flow sensor 3 to a counter operating the pump solenoid 14. The electronic control allows the mixing ratio of detergent to water passing through the dosing pump 4 to be varied as required for a particular application. The use of an electronic circuit eliminates excessive moving parts while allowing precise control of the mixing ratio.

The auto line cleaner is housed in a wall mounting cabinet which contains the controller, detergent dosing unit and a manifold capable of cleaning up to eight beer lines simultaneously (see Figure 3). Where multiple beer lines are connected to each keg, a larger number of lines can be cleaned.

When the auto line cleaner is activated, the operator follows a simple sequence of instructions presented on the system display. The instructions guide the operator through the following processes.

a) removing the beer lines from the kegs and connecting them to the auto line cleaner; b) connecting drain hoses to the taps in the bar; c) checking for the presence of sufficient detergent to complete the cycle.

When the set up procedure is complete, the cleaning cycle is activated and the controller steps through a sequence of detergent wash and rinse phases. During the wash cycles the detergent to water ratio is accurately maintained by the controller. A typical wash rinse and wash cycle might be: i) Rinse each line individually 15 mins.

ii) Mix detergent and wash each line individually 15 mins.

iii) Allow detergent to stand in line to soak-clean 15 mins.

iv) Rinse with water and re-wash (as in iii) 30 mins.

v) Final rinse of lines 15 mins.

The operator is then requested to restore the beer lines.

A setup menu allows idividual run times to be programmed for each line to account for run lengths, lift etc. The detergent to water mixing ratio can also be programmed from this menu. Access to the setup menu can only be made by activating a switch positioned within the cabinet. Setup parameters are retained when the unit is switched off.

The operation sequence of the semi-automatic cleaning system is as follows: Signals from an inline flow sensor 36 are fed into the signal conditioner at a rate proportional to the fluid flow; The signal conditioner ensures that the flow signal is 'square wave' in form, although the output from flow sensor maybe a sine wave; The position of the wash/rinse switch is set to 'wash', counter 43 counts down from 10 and then outputs a 'carry' signal to counter 42. Counter 43 therefore divides the signal from the flow-sensor by 10.

Counter 42 counts down from a preset value between 0 and 99 subtracting 1 for every signal out of counter 43. The preset value is set using switches 40 to 41, the switches have clock faces to show the preset value.

Having counted down from the preset value a signal is output from 42 to monostable 37; In Fig. 3 the preset block switches are set to 46 giving a divide by 46 setting. The overall divide ratio for the unit is 1/10 x 1/46 = 1/460 counter 43 counter 42 overall ratio Ratio between 0 and 999 are therfore possible in steps of 10; Monostable 37 then 'tunes' the output signal from the counters which is very short to a signal at sufficient size and length to fire the field effect transistor 38; The field effect transistor 38 needs to be 'on' for a period long enough to allow the solenoid 14 to fully stroke the piston in the pump.

The beer line cleaning systems of the present invention have the following advantages: 1. increase the efficiency of beer line cleaning, thereby increasing the beer quality; 2. save time by releasing the operator during the cleaning process; 3. ensure consistency of cleaning cycles by maintaining correct ratio of water to detergent mixing; 4. step by step help screens, issued from a panel display built into the unit; 5. individual line clean times programmed from an easy to use menu (which features protected access) 6. programmable water to detergent ratio, set from easy to use menu; 7. optimal manual cycle step menu; 8. log or date, time and duration of each cleaning cycle, available for collection by Psion organiser or portable PC; 9. alarm on detergent empty.

The fluid dosing and mixing system described is used to carry out the automatic line cleaning for beer or soft drink lines. However, it will be appreciated that the fluid dosing system and dosing pump according to the invention has many other applications. For example it could be used to meter and mix fluids such as chemicals for use in agriculture, or ice-cream mixes.

Claims

CLAIMS:

1. A fluid dosing and mixing system comprising a dosing pump, a flow sensor in a line to the pump for the supply of a fluid to be mixed, a control for the supply of fluid and an inlet for the supply of the fluid to be metered by the dosing pump, wherein an electronic unit controls the rate of operation of the pump in proportion to the flow of fluid through the flow sensor.

2. A fluid dosing and mixing system as claimed in Claim 1, wherein a control unit is provided to operate a wash and rinse cycle for the fluid dosing and mixing system.

3. A fluid dosing and mixing system as claimed in Claim 1 or 2, wherein the system includes a priming unit to prime the dosing pump.

4. A fluid dosing and mixing system as claimed in any preceding claim, wherein the system includes electronic counters connecting the flow sensor and a solenoid of the dosing pump to control the dosing ratio of the mixing system.

5. A fluid dosing and mixing system as claimed in Claim 6, wherein the processing is under the control of a plurality of switching transistors.

6. A fluid dosing and mixing system as claimed in Claim 5, wherein the solenoid is primed by a monostable via a field effect transistor, and an oscillator feeds a series of signals to the monostable.

7. A fluid dosing and mixing system as claimed in any of Claims 4 to 6, wherein a microcontroller is connected with a display unit.

8. A fluid dosing and mixing system as claimed in Claim 7, wherein the display unit incorporates visual indicating means in the form of switches with position measuring in tens and units.

9. A dosing pump for dosing a predetermined volume of fluid to mix with a second fluid, comprising a body secured to a solenoid, said body being closed by a cap having a passage for a fluid flowing therethrough, an axial bore in the body connecting with the passage in the cap, a piston operated by the solenoid to reciprocate within the bore to meter a dose of fluid fed to the bore into the passage, and non-return valves located in the fluid flow passage to the bore and between the passage and bore to prevent backs low of the fluids being mixed.

10. A dosing pump as claimed in Claim 9, wherein the piston is spring-loaded.

11. A dosing pump as claimed in Claim 9 or 10, wherein the non-return valve between the passage and the bore is a spring loaded needle in co-operation with a ball valve.

12. A fluid dosing and mixing system substantially as hereinbefore described with reference to and as shown by the accompanying drawings.