CA1047983A - Method and apparatus for dispensing a beverage - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Apparatus for mixing and dispensing a beverage has a mixing head, a water line having a partially restricted outlet for backing up water pressure, a concentrate chamber having a diaphragm, a bypass line from the water line to the chamber for bypassing water from the water line against the diaphragm and forcing concentrate to the mixing head, and an open drain in the bypass line for exhausting water from the con-centrate chamber; also disclosed is a method of mixing and dispensing a beverage in which pressurized water is first used to propel concen-trate and then exhausted out a drain.

Description

~4791~3 BACKGROUND OF THE INVENTIOR

FIELD OF THE INVENTION
This invention pentains to apparatus and a method for dispensing a beverage in which pressurized water is used to propel beverage concen-trate and is then exhausted to a drain.

PRIOR ART ~ ;~
The prior art devices include the apparatus and method d;s~
closed in U.S. Patent 3,779,261. Further examples of the prior art are B. G. Copping 2,495,210j E. S. Wegman 2,502,610 and N. L. Luster 2,538,111.
All of these examples of the prior art disclose beverage dispensers which utilize the energy available in and from pressurized water to propel beverage concentrate to a mixing head.
For example, in the dispenslng of carbonated beverages it is common to use and mix 5 parts of water and 1 part of syrup by volume to ~ form a fin;shed palatable beverage. In these prior devices, l part of ; 15 water ls bypassed or backed up to displace and propel l equal quant;ty of concentrate from a water actuated metering chamber or pump to a mixing head. As w;ll be appreciated, when a cup is f;lled with beverage, the dispenser operator closes the dispensing valve or valves and terminates dispensing.
The problem then presented ls what to do with or how to d~s-pose of the l part of propellent water that is left in the concentrate ; chamber. The given examples of the prior art all dribble the ~ater outthe d;spens;ng head or mix;ng head a~ter the dr;nk is dlspensed and during th;s dr;bbl;ng of water, the concentrate chamber is refilled with concentrate for the next dispensing cycle.
This problem was recognized by B. G. Copping and his solution is disclosed in his U.S. Patent 2,748,982~ Copping provides a solution for post or after-dispensing dribble of propellent water from a dispensing apparatus such as that in his Patent 2,495,210. ~ .

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~q~47983 Copping's solution is to remove the simple and single element on-off dispensing control valve in the pressurized water 1ine and to install a triple element valve of the stacked poppet type where there is a central shaft and three poppet valves one on top of each other. Of these three poppet valves, two are normally closed and one is normally open. The pressurized water line outlet is normally closed and a water line to the mixing head is normally closed; a water drain line from a concentrate chamber to a drip tray or waste line is normally open. A
separate single element normally closed valve is provided ~or Copping's concentrate outlet and is connected to yet another valve which opens the `.
outlet for dispensing of mixed water and concentrate.
The gist of ~opping's solution in 2,7~8,982 is that he provides ; "
a normally open outlet ~rom a bypass l;ne to a drain for exhausting used water from the syrup pump and he manually closes a water exhaust valve ln combination with open;ng o~ water inlet and concentrate outlet valves, to pressurize a concentrate chamber and effect simultaneous dispens;ng of water and concentrate.
The apparatus and sequential operation of the device of U.S.
Patent 2,748,982 will, upon review of the patent, be reali~ed as being costly, complicated and having many co-functional components needing to be correctly operatively synchronized together for proper operation as intended by Copping. Further, the dev;ce does not lend itself to a mul-tiple flavor dispenser of beverages.

SUMMARY OF THE INVENTION
In accordance w;th this invention, an apparatus ~or m~xing and d;spensing a beverage is provided and having a mixing head, a water line connected to the mixing head and having a water dispensing control valve and a partially obstructed outlet for backing up water pressure, a concen- ;
trate chamber having a diaphragm therein and an outlet to the mixing head, a bypass line from the water line to the concentrate chamber for trans-ferring water under backed up pressure against the diaphragm for forcing ;;
` concentrate to the mixing-head, and an open drain for exhausting bypassed ... .

~ 04~83 water from the bypass line during and after dispensing; a method is also provided in accordance with this invention in which bypassed press- `
urized water used for propelling and dispensing beverage concentrate is exhausted to a waste drain during and after dispens;ng at a controlled rate which is sufficient to maintain a bypass pressure during the dis-pensing of beverage.
Accordingly, it is an object of the present invention to provide apparatus for m;xing and d;spensing a beverage, us;ng water for propell;ng concentrate and having a drain for exhausting used propellent water.
It is an object of the present invention to provide apparatus for mixing and dispensing a beverage having a water pressure powered concentrate pump with a water drain of an extremely simple, reliable and low cost configuratlon.
lS It is a further object of the present ;nvention to provide apparatus for m;x;ng and dispensing a beverage, hav;ng a water powered concentrate pump wh;ch does not dra;n propellent water from a dispensing head.
It is still a further object of the present invention to pro- ;~ -v;de a method of dispensing a beverage using water for pump;ng concen-trate and drain;ng the water used for pump;ng power d;rectly to a waste l;ne.
Many other advantages, features and additional objects of the present invention will become man;fest to those versed ;n the art upon making re~erence to the ~etailed description and the accompany;ng sheet o~ drawing in which a preferred structural embodiment incorporat;ng the i;`
princ;ples of the present ;nvent;on ;s shown by way of illustrative example.

ON THE DRAWING:
FIG. 1 is a schematic drawing of apparatus for mixing and ~ 3 `
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3L~9~7 ~8 3 d;spensing a beverage, provided in accordance wlth the pr~nc;ples of the present invention.

AS SHOWN ON THE DRAWING: .
The principles of the present invention are particularly .
useful when embodied in a beverage dispenser of the type illustrated in ~ ~.
FIG. 1 and yenerally indicated by the numeral 10.
The dispenser 10 includes a dispensing or mixing head 11, a water line 12, a concentrate reservoir 13, a concentrate metering chamber 14, a diaphragm 15 in the metering chamber 14, a bypass line 16 connecting the water line 12 to the metering chamber 14 and a drain 17 in the bypass line 16.
The water line 12 is adapted to be connected at its inlet and to a source of pressurized water, such source may be either carbonated ~ ;
or flat water and should have a pressure of at least 7 PSIG. If the ~;
lS pressure of the water source is excessively high~ a pressure regulator may be installed in the line which is a well known practice. There is a normally closed valve 18 in the water line 12 which is opened to allow flow of water and closed to stop flow; valve 18 thereby controls opera- ~:
tion of the dispenser 10. The water line 12 continues past the valve 18 to the mixlng head 11. There is a partially obstructed opening 19 in the water line 12 downstream of the water valve 18. In the embodiment shown, the obstructecl opening 19 is formed by an adjusting screw 20 which enables ad~ustment of the size or cross section of the partially obstructed opening 19. Between the water valve 18 and the partially obstructed opening 19 there is a length of the water line 12 which Forms a bypass chamber 21 and into which Flowing water is backed up by the obstructed opening 19. There is a bypass outlet 22 from chamber 21 connected to the bypass line 16 for purposes to be later explained.
Concentrate reservoir 13 is for holding a supply of beverage concentrate. Below reservoir 13 there is a metering chamber 14 which in ; .
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the beverage art ;s many times also referred to as a concentrate or syrup pump. Reservoir 13 is fluidly connected to metering chamber 14 through a check valve 23 which is shown as having a simple rubber flapper, and is positioned to allow free flow of concentrate from reservoir 13 to metering chamber 14 and to preclude flow from metering chamber 14 to reservoir 13.
Flow of concentrate through check valve 23 is by force oF gravity upon the concentrate. There is a concentrate outlet line 2~ from metering chamber 14 to the mix;ng head 11. The concentrate line 24 has a valve 25 for controlling flow of concentrate in line 24. The concentrate valve 25 must control concentrate flow so that concentrate cannot go backwards in the line 24 and fill line 24 with air. The valve 24 can be a normally closed valve which is operatively connected to work with the water valve 18 or can be a check valve which allows outwardly directed flow only. ~
There may be an adjustable concentrate flow rate control 26 in line 24 ~ ;
lS which can be either upstream or downstream of the concentrate valve 25. `~
In the embodiment shown, concentrate flow rate control 26 is adjustable.
The metering chamber 14 is divided or separated into two parts ~
by the diaphragm 15 for physically separating concentrate and bypass water ;~; ;as will be explained. The diaphragm 15 is mounted to and retained in place by a removable cover 27 fastened to the outer case 28 of the ; ;
metering chamber 14. The cover 27 has a round tubular section 29 extending into the metering chamber 14 and upon which the diaphragm 15 is secured by a stretched 0-ring 30. The diaphragm 15 is of an elastically stretchable ; `
elastomer such as latex and is formed as an elongate cylinder. As an example, an excellent diaphragm 15 is made by a cylindr~cal rubber balloon. This diaphragm 15 when expanded is elastically stretched and biases itself from the expanded configuration toward its normal configu-ration with a force or pressure of about 1.2 PSIG.
The diaphragm 15 has a normal unstressed configuration which is cylindrical as is shown in solid line. Under the pressure of concen-trate flowing by gravity from the reservoir 13 into the metering chamber ....... -;- ~

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14, the dlaphragm 15 c~mpletely collapses into the alternative conf;gu-ration shown in dotted line as 15c. When the d;aphragm 15 is blo~n up under pressure of bypass water for pumping concentrate as will be later explained, it will expand to a shape indicated in dot~ed line by 153 which almost completely fills the metering chamber 14. The concentrate outlet line 24 has a screen 31 which prevents the diaphragm 15 ~rom extruding out the concentrate line 2~. It has been found that the metering chamber 14 works well when sized to have a volume of approxi-matel~ 200 cc; this gives a pumping capacity of about 190 cc of concen-trate per cycle. It has been found that the diaphragm 15 is completelyexpanded by an internal pressure of 1.5 PSIG and that the entire 190 cc is pumpable by that pressure.
In order to pressurize the interior of the diaphragm 15, the bypass line 16 is connected from the water line 12 to the metering -chamber 14. The bypass line 16 is fluidly connected to the water line 12 at the bypass outlet 22 of bypass chamber 21. An adjustable bypass flow control 32 is provided for enabling adjustment of the amount of :
water flowing into and through bypass line 16. The bypass line 16 is fluidly connected at its other end to one side of the diaphragm 15 by 20 metering chamber cover 27 which has an internal port having a diaphragm :
inlet 34 in fluid connection with the interior of the diaphragm 15 A very important feature of the present invention ~s the provision of the bypass water drain 17 in the bypass line 16. Although the drain 17 is shown as being in the cover 27, the entirety of the fluid passageway from the water line 12 to the dlaphragm 15 is considered as the bypass line 16 and the drain 17 may be anywhere between a check valve 35 and the diaphragm inlet 34. The metering chamber cover 27 is made of a rigid plastic and has means for holdin~ the diaphragm 15 as previously explained, and for economy of fabrication and simplicity has both the drain 17 and the diaphragm inlet 34, which connects the ~ ~47~83 bypass line 16 to the diaphragm 15, located immediately adjacent to one another as is shown. The entire bypass line 16 is relatively unrestricted to the rate of normal water flow therethrough save for the adjustable flow control 32 which is for precisely restricting and controlling -flow into line 16, and the drain 17 is sized to have a greater restriction to water flow than any restriction in the bypass line 16.
An important feature of the invention is the relative sizing of the drain 17. The dra;n 17 is an open aperture o~ fixed size. The cross section of the drain 17 is sized to retain water by surface ten- ;
sion or capillary action so that once the bypass line is primed~ it ~ ;
retains its prime between dispensing cycles. It has been found that a preferred drain 17 sizing is a .052 inch diameter by 1/4 inch long aperture. The drain 17 sizing preferably has an area equivalent to ;
the area of a diameter in the range of 1 to 2 mm and it has been found that this area provides for retention of a prime of bypass water in the bypass line 16 during the period of non-use of the dispenser 10 and during which period the bypass line 16 is not pressurized. Another and an important feature of the drain 17 is that it be sized to form the greater restriction to flow of bypass water either through or from the bypass line 16.
There is a bypass check valve 35 Fluidly mounted in the bypass line 16. The bypass check valve 35 is mounted between the water line 12 and the drain 17 and is operative to allow flow of bypass water from line 12 to the meter~ng chamber 14 and to preclude water flow from the metering chamber 14 to water line 12. The bypass check valve 35 is shown as belng an extremely economical type of valve commonly known as a "thomas" valve and is shown ;nstalled in the metering chamber cover 27.
It will be noted that an adjustable water flow control 36 may be placed ;n water line 12, and that the water valve 18 and the concen- ~ ;
trate valve 25 may be operatively connected for simultaneous or sequen-tial operation as a particular beverage may require.
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f~` 1047983 The dispenser 10 has a conventional waste outlet or drain 37 ;
which gathers waste or slopped beverage from the mixing head 11 an~
bypass water from the drain 17 and routes it for disposal.
In operation of the dispenser 10, the water 1ine 12 is con-nected to a source of pressurized water which may be regular tap water, carbonated water or any other aqueous diluent. A beverage concentrate or syrup is placed within the reservoir 13. A typical soft drink con-centrate is concentrated 5 to 1 or it requires 5 parts water be blended to 1 part of concentrate to form a finished drink. Fruit or vegetable juice concentrates are usually less concentrated and are reconstituted at the ratio of 2.5 or 3.0 to 1. Other concentrates such as tea or coffee may require 6 or more parts of water for proper blending. It is a feature of the present dispenser 10 to be able to accommodate these many different concentrates or syrups.
As the reservoir 13 is being initially filled, concentrate flows under the force of gravity through the check valve 23 into the ~;~ metering chamber 14 and collapses the diaphragm 15 to the configuration shown in dotted line l5c and concentrate fills the metering chamber 14.
The first or initial opening of water valve 18 primes the bypass line 16 and the concentrate outlet line 24. As the water valve 18 is opened, water flows through line 12, past flow control 36, through valve 18, into the bypass chamber 21 and then through the partially obstructed outlet 19 and then out the mixing head 11 and into either the cup or the waste outlet 37.
When the flowing water begins to flow through the partially obstructed opening 19, the pressure which the water is under~from the pressure source is partially backed up and developed at least in part in the bypass chamber 21 as a bypass pressure. Some of the water in the bypass chamber 21 is then directed or forced by the bypass pressure through the bypass outlet 22 into bypass line 16, through the check . ~
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1;~347~83 valve 35 and against the diaphragm 15. This portion of water from line 12 which is directed through the bypass line 16 is hereinafter called the bypass water. As the bypass line 16 is primed, all air in the line is driven out of the drain 17. When the bypass water reaches and makes contact with the diaphragm 15, its flow is resisted by the concentrate in the metering chamber 14 and the bypass pressure begins to build up - ~
in the bypass line 16 and inside of or against one side of the diaphragm ` ~`
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15. As the bypass pressure builds up, bypass water begins to flow out of the drain 17 but due to the predetermined restrictive size of the drain 17, the bypass pressure is maintained within the bypass line 16 and against the diaphragm 15.
The bypass pressure continues to force bypass water into bypass line 16 and against the diaphragm 15 which initially is in the collapsed configuration of 15c and the diaphragm lS begins to expand from the collapsed configuration of 15c to the normal configuration of 1515 and then to the expanded configuration 153 as will be later explained.
As the diaphragm 15 is expanded by bypass water, the bypass pressure is transferred through the diaphragm 15 to the concentrate in the metering chamber 14. The check valve 23 prevents concentrate flow back into the ~ `
reservoir 13 whereupon the concentrate is Forced from the metering chamber 201~ ~nto and through the concentrate outlet line 24, past flow control 26 and valve 25 to the mixing head 11.
After the dispenser 10 is primed and both water and syrup are flowing from the mixing head 11, the ratio of water to concentrate must be ad~usted to obtain the desired and proper beverage. In order to do 25the adjusting, the water and syrup flows are divided before mixing and the correct water flow is approximated. As an example, if the total dispensing rate is to be 60 cc per second and the ratio is to be 5 parts water to 1 part concentrate, a water flow rate of 50 cc per second is needed. Firstly, the adjustable p~rtially obstructed opening 19 is 30opened to its maximum size and then the water flow control 36 or else ~_ 9 ~ .: -, , . . : ~ , . . . .

a water pressure regulator (not shown) is adiusted to give a water flow rate coming from the mixing head in excess o~ the total drink rate, for example, a flow rate of 65 cc or greater. The partially obstructed opening 19 is then reduced in size to give the desired flow ra~e of water, i.e., 50 cc per second which rèstricts the flow of water and backs up at least part of the water supply pressure forming the bypass pressure in bypass chamber 21.
The concentrate flow control 26 may be set at approximately its halfway setting between m;nimum and maximum flow rates and the bypass flow control 32 is then adjusted to give a flow of bypass water against the diaphragm 15 which will displace concentrate and propel it out of the mixing head 11 at the approximate desired rate, i.e., 10 cc per second. The partially obstructed outlet 19 and adjusting screw 20 can then be finely reset to give the precise 50 cc per second water flow and the concentra~e flow control 26 can then be set to finely control the concentrate flow rate at a precise 10 cc per second.
After the dispenser 10 is primed, a prime of bypass water is reta;ned within the bypass line 16 by the drain 17 which is s;zed for allowing the bypass water, which has previously d;splaced the concen-trate, to drain as will be descr;bed but also to retain a prime oFbypass water by capillary action or surface tension in the relatively small bore of the drain 17. A prime of concentrate is reta;ned ;n the concentrate line 24 by the valve 25 wh;ch controls concentrate ~low so that concentrate cannot flow backwards in the line 24. After prim;ng, the metering chamber 14 is refilled with concentrate by flow under the force of gravity and the diaphragm 15 collapsed to the conf;guration of 15e and the bypass water wh;ch prev;ously displaced and propelled the concentrate is drained out of-the drain 17 as will be la~er explained.
The dispenser 10 is then ready for a regular dispensing cycle dur;ng which the operation is as follows. D;spensing of a drink is started by opening the water valve 18 and concentrate valve 25 if it ; - 1 0 `` ..

is cooperative with water valve 18. Water under source pressure beg;ns '~
to immediately flow thro~lgh line 12 and the partially obstructed outlet 19 builds up the bypass pressure in bypass chamber 21 which forces bypass water through and past bypass flow control 32, into bypass line 16 through check valve 35, and against the collapsed diaphragm lSc.
The bypass line 16 was previously primed so the concentrate in metering chamber 14 is immediately displaced by the incoming bypass water and forced out the concentrate outlet line 24 to the mixing head 11. As the bypass water begins flowing under bypass pressure into the diaphragm 15, the diaphragm 15 begins to expand from the collapsed configu-ration of 15c toward the configuration 15. During this expansion, the diaphragm 15 creates absolutely no resistive pressure against the incoming bypass water but during further expansion of the diaphragm from the con-figuration of 15 to 15e a resistive pressure of about 1.2 PSI is made by the diaphragm 15. When the diaphragm 15 is fully expanded to the configu- -~
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ration of 15e, the screen 31 preven~s the expanded diaphragm From extruding into the concentrate outlet line 24.
The normal dispensing cycle is completed before the diaphragm 15 completely expands to the configuration 15e. For example, a normal -. ~
cup of beverage may hold approximately 300 cc which would require from 200 to 270 cc of water and from 30 to 100 cc of concentrate over a ; ;~blending ratio range of from 3:1 to 9:1. The meter;ng chamber, as previously stated, is sized at about 200 cc volume if the dispenser 10 is intended to Fill one cup at a time and only part of the chamber volume is used. `!'~`
When the water valve 18 is closed, flow of both water and concentrate stops immediately and concurrently because oF the almost immediate dropping or loss of the bypass pressure. During the dispensing flow of bypass water and concentrate, the drain 17 is always open and a minimal quantity of bypass water is wasted as will be described. The ''' 1 1 ' :. . ' ' : ~".' '' ~ . :

~47983 bypass water flows into and through bypass line 16 and through check valve 35 and internal port 33 and inlet 34 to the diaphragm 15. The bypass pressure is simultaneously applied to the diaphragm 15 and the drain 17 and a certain quantity of bypass water will be wasted out of the drain 17. The drain 17 is sized, as was previously explaineda to restrict flow of bypass water therethrough during dispensing so that the bypass pressure needed to displace the concentrate is not lost out the drain 17. It will be appreciated that by minimizing the bypass pressure a minimum of water will be wasted through drain 17, and to that end, adjustable controls 20, 26, 32 and 36 are provided. The drain ~ ;17 is sized to restrict the waste water flow rate to a lesser rate than the rate of flow of concentrate during dispensing. As an example, when the bypass pressure and water are driving concen~rate out of metering `~
chamber 14, anyqhere from an additional 1/10 to 1/2 quantity of water may be passed by the drain 17. Specifically, in the propelling of 50 cc of concentrate from the metering chamber 14, an additional 5 to 25 cc of water may be needed for waste provision. This explains why the water flow control 36 is set to a flow rate greater than the total desired flow rate out of the mixing head 11. The flow of waste bypass water out of draln 17 is routed into the waste outlet 37 ~or disposal.
When the water valve 18 ~s closed and a dispensing cycle is terminated, the bypass pressure immediately drops and the flow of bypass water into line 16 ceases. The check valve 35 closes preventing back~low ,' o~ bypass water up the bypass line 16 and dribbling ~rom the mixing head 11.
i ~5 It will be apparent that the metering chamber 14 must now berecharged with concentrate~ Concentrate valve 15 is closed, be it a check valve or an open-close valve co-functional with water valve 18. The con-centrate in the reservoir 133 under force of gravity, opens the check valve 23 and begins to flow into and refill the metering chamber 14.
During this refilling, the previously used bypass water is released through . ..

4~9~3 the drain 17, which to repeat is always open. The rate of refill is determined by the rate of flow of water out of drain 17. If the diaphragm ~ -15 has been expanded past configuration 15, it will give a small pressure boost to drive waste water through the drain 17. Typically, the refilling of the metering chamber will take from 2 to 3 times as long as the dis-pensing time. The incoming concentrate, under force of gravity, will `'~
completely collapse the diaphragm 15 to the configuration of lSc. When ` ; ~
the metering chamber 14 is refilled, flow of previously used bypass water ~ ;
through the drain 17 ceases but the small size of the drain 17 retains a prime of bypass water for the nex~ dispensing cycle.
The diaphragm 15 is easily cleaned or replaced as it may be ;~
easily removed by removal of the cover 27 from the metering chamber 14 .~
and removal of the retaining 0-ring 30.
It will be appreciated from the foregoing that this dispenser ~ `
10 is of extremely simple construction and is virtually foolproof as it does not require complicated valving and the like. It is particularly well adapted for use in a home where the water line 12 is hooked to the i house water supply.
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If the dispenser 10 is to be used only with a specific concen~
trate and predetermined water supply pressure, it can be further simpli-fied by removal of some of the adjustable flow control elements, but For purposes of illustration an adjustable dispenser 10 capable of dispensing ~`
virtually all types of beverages is shown and described~ ~`
Although various and minor modificatians may be suggested by 25 those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon, all such embodiments as reasonably and properly come within the scope of my contribution to the art. ` ``
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Claims (18)

The embodiments of the invention in which an exclusive pro-perty or privilege is claimed are defined as follows:

1. Apparatus for mixing and dispensing a beverage comprising:
a dispensing head for mixing of water and beverage concentrate, a water line having one end for being connected to a supply of pressurized water, a valve for control of flow of water through the line, and a water chamber downstream of the valve and having a partially obstructed outlet for deve-loping pressure in the chamber during flow of water therethrough, the outlet being in fluid communication with the dispensing head; a reservoir for containing a supply of beverage concentrate; a concentrate metering chamber in fluid communication with the reservoir and being fillable from the reservoir; a valve between the reservoir and the metering chamber for allowing concentrate flow from the reservoir to the metering chamber and for preventing concentrate flow from the metering chamber to the reservoir;
a concentrate line between the metering chamber and the dispensing head, there being a valve in the concentrate line for controlling flow of con-centrate therethrough; a bypass line fluidly connecting the water chamber to the metering chamber for bypassing water from the water chamber to the metering chamber under the pressure formed by the flow of water through the partially obstructed outlet; a divider positioned in the metering chamber for physically separating concentrate and water in the metering chamber, the divider being movable upon flow of and under the pressure of bypassed water flowing into the metering chamber, for pressurizing the concentrate in the metering chamber and forcing concentrate through the concentrate line to the dispensing head; and a bypass drain in fluid communication with the bypass line for the discharge of only bypassed water to a waste outlet, the drain being open and sized for restricting drainage flow of bypassed water during dispensing, and for allowing drainage of bypassed water during filling of the metering chamber with concentrate.

2. Apparatus according to claim 1, in which the drain is sized to have a greater restriction to water flow than any restriction to flow in bypass line into the metering chamber.

3. Apparatus according to claim 1, in which the drain is an open aperture of fixed size.

4. Apparatus according to claim 3, in which the drain is sized to retain water in the bypass line when the bypass line is not pressurized.

5. Apparatus according to claim 4, in which the drain has the area of a diameter in the range of 1 to 2 millimeters.

6. Apparatus according to claim 1, in which the drain is immediately adjacent to the connection of the bypass line to the metering chamber.

7. Apparatus according to claim 1, in which the divider is a diaphragm freely collapsible under the weight of concentrate flowing by gravity from the reservoir into the metering chamber.

8. Apparatus according to claim 1, including a pressure actuated check valve fluidly connected in the bypass line between the water chamber and the drain, the bypass check valve being operative for allowing flow of bypass water only from the water chamber toward the metering chamber.

9. Apparatus according to clam 8, in which the divider is a diaphragm having means for biasing itself from an expanded position toward a collapsed position during filling of the metering chamber with concentrate.

10. Apparatus according to claim 1, including a flow control fluidly connected to the bypass line for control of the rate of flow of water into the bypass line.

11. Apparatus according to claim 1, the partially obstructed outlet is adjustable in size.

12. A method of mixing and dispensing a beverage comprising the steps of: opening a valve and passing a flow of water through a line from a pressurized water source to a dispensing head; partially obstructing the flow of water and developing a bypass pressure down-stream of the valve when the valve is opened; providing a beverage concentrate in a metering chamber; directing water under the bypassing pressure in the water line from downstream of the valve to the metering chamber and against a divider in the chamber; draining a portion of the bypassed water from the bypass line while transferring the bypass pressure across the divider and forcing concentrate from the metering chamber to the dispensing head; mixing the water and the concentrate at the dispensing head to form a drinkable beverage; closing the valve;
and subsequently draining the bypassed water directly from the bypass line to a waste outlet while refilling the metering chamber with concentrate.

13. A method according to claim 12, including the step of retaining a prime of bypassed water in the bypass line after completion of the subsequent draining.

14. A method according to claim 12, including the step of restricting the drainage flow of bypassed water during dispensing.

15. A method according to claim 14, in which the drainage flow of bypass water during dispensing is restricted to a lesser rate fo flow than the rate of flow of concentrate forced from the metering chamber to the dispenser head.

16. A method according to claim 12, in which the subsequent draining of bypass water is effected at least in part by the refilling of the metering chamber with concentrate flowing under the force of gravity.

17. A method according to claim 12, including the step of checking against flow of bypassed water from the metering chamber to the dispensing head during the subsequent draining.

18. A method according to claim 12, including the step of controlling the rate of flow of water into the bypass line.