Device for introducing an additive liquid into a carrier liquid flowing in a pipe

A device for introducing an additive liquid into a carrier liquid, which comprises a pipe section with a venturi in which the carrier liquid is caused to flow. A first tube has an end connected to the pipe section upstream of the venturi, while a second tube of small diameter is formed in the walls of the first tube and pipe section. The second tube has a two-branched end defining a first orifice in the pipe section downstream of the venturi and a second orifice inside the venturi. The first and second tubes comprises adjacent free ends. A third tube has an end communicating with a first compartment of a plastic bag, while a small diameter fourth tube formed within the wall of the third tube has an end communicating with a second compartment of the bag containing the additive liquid. The third and fourth tubes comprise adjacent free ends. A quick-fit connector removably and simultaneously connects together the free ends of the first and third tubes, and the free ends of the second and fourth tubes. In operation, the carrier liquid is transmitted in the bag first compartment through a pressure limiting valve mounted in the first tube. When the valve is open or closed, additive liquid is introduced in the carrier liquid through the first or second orifice, respectively.

BACKGROUND OF THE INVENTION 
1. Field of the invention: 
The present invention relates to an improved device for introducing an 
additive liquid into a carrier liquid which is caused to flow in a main 
pipe. 
2. Brief description of the prior art: 
Prior art additive liquid introducing devices of the above type are known 
which use a difference in pressure produced by a constriction formed in a 
main pipe through which the carrier liquid is caused to flow. A container 
is divided in two compartments by a flexible, impermeable. membrane, and 
has its first compartment connected through a first conduit with the main 
pipe upstream of the constriction and its second compartment, containing 
the additive liquid, connected through a second conduit with the main pipe 
at the constriction or downstream thereof. The container is usually 
connected to the main pipe through two separate connections, while the 
second compartment can often be refilled with additive liquid. 
In operation, the carrier liquid from the main pipe is transmitted in the 
first compartment through the first conduit. As the pressure of the 
carrier liquid upstream of the constriction is higher than that in the 
constriction or downstream thereof, the carrier liquid in the first 
compartment applies a pressure on the additive liquid through the flexible 
membrane. The additive liquid is then introduced in the carrier liquid in 
the constriction or downstream thereof through the second conduit. 
Such prior art additive liquid introducing devices are described, for 
example, in U.S. Pat. Nos. 
______________________________________ 
2.865.388 
(STERNBERGH) December 23, 1958 
2.932.317 
(KLOSSE) April 12, 1960 
3.166.096 
(LANG) January 19, 1965 
3.220.435 
(ELLINGSON) November 30, 1965 
3.720.230 
(STOCKSTILL) March 13, 1973 
4.210.175 
(DANIELS et AL) July 1st, 1980 
______________________________________ 
As the above listed United States Patents describe two separate 
connections, often permanent, of the first and second compartments of the 
container with the main pipe, the use of disposable containers having 
their second compartment already filled with additive liquid upon purchase 
would necessitate two time consuming and tedious disconnection-connection 
operations each time the container is changed. It is the reason why, in 
the prior art additive liquid introducing devices, the container is often 
permanent, and is designed for refilling of its second compartment with 
additive liquid. 
An important drawback of the above described prior art additive liquid 
introducing devices is that they are bulky and relatively expensive. It is 
therefore expensive to mount some of them, as an example, on different 
water pipes for introducing different liquid medicaments in these 
different pipes separately supplying with water different animals in order 
to achieve different medications on these different animals. Also it is 
known to mount a prior art introducing device on a pipe supplying with 
water a plurality of animals; the drawback is that the introduction of a 
liquid medicament in the water causes supply of the same to all the 
animals even if only one needs it. As the prior art additive liquid 
introducing devices are bulky, a plurality of such introducing devices 
cannot be mounted on a same pipe for simultaneously introducing different 
additive liquids in the carrier liquid. Moreover, since the prior art 
devices are often permanently installed, they cannot be easily displaced 
from one pipe to the other. 
Appropriate cares must also be taken when refilling with additive liquid 
the second compartment of the permanent container. First of all, when 
different additive liquids have to be successively introduced in the 
carrier liquid, the second compartment must, in most of the cases, be 
carefully washed in order to prevent mixing of incompatible additive 
liquids. When the additive liquids are medicaments, such mixing can 
produce toxic substances or a medicament with a reduced efficiency. 
In the case of a medicament, water or another medicament must often be 
mixed thereto prior to refilling the second compartment. If such mixing is 
carried out without precautions by an unskilled person, for example in a 
non-sterile vessel, the medicament is contaminated. 
U.S. Pat. No. 3.392.753 (KLEINMANN) issued on July 16, 1968, discloses an 
additive liquid introducing device of the above type using a disposable 
container. Again, the first and second compartments are connected with the 
main pipe through two different conduits. Replacement of the container 
therefore requires two different disconnection-connection operations. The 
container is formed by plastic bottles or jugs having an inner, flexible 
membrane. These bottles or jugs can be purchased with their second 
compartment filled with the additive liquid, and are disposed of after 
use. Such plastic bottles or jugs constitute relatively expensive 
disposable units. 
A further drawback of the prior art additive liquid introducing devices is 
that each device can introduce in the carrier liquid only one additive 
liquid at the same time. Consequently, the user is prevented from 
simultaneously introducing in the carrier liquid different additive 
liquids which cannot be mixed beforehand, for example medicaments, 
possibly with different concentrations. 
OBJECTS OF THE INVENTION 
A first object of the present invention is therefore to provide an additive 
liquid introducing device with a disposable container which can be easily 
replaced in a single disconnection-connection operation, by means of a 
quick-fit connector. 
A second object of the present invention is to provide an additive liquid 
introducing device of low cost and of small dimensions, whereby a 
plurality of such small-dimension introducing devices can be mounted at 
reasonable cost on different pipes to introduce different additive liquids 
in the carrier liquid flowing in these different pipes, or a plurality of 
such small-dimension introducing devices can be mounted also at reasonable 
cost on a same pipe to simultaneously introduce in the carrier liquid 
flowing in this pipe a plurality of different additive liquids. As an 
example, when different introducing devices are mounted on different pipes 
separately supplying with water different animals, only the necessary 
medicament can be introduced in the water supplied to each animal and that 
in the required quantity. An economy of medicament therefore results. 
A third object of the present invention is to provide an additive liquid 
introducing device of low cost and small dimensions which can be easily 
transferred from one pipe to the other. 
A fourth object of the present invention is an additive liquid introducing 
device using as container a disposable low-cost unit including a 
two-compartment bag made of thin, flexible and impermeable material, such 
as transparent plastic. The disposable unit is purchased with the second 
compartment of the bag sealed and filled with additive liquid. As the 
second compartment of the bag is sealed no contamination of the additive 
liquid is possible. Moreover, both mixing of the additive liquid which can 
cause contamination of the latter, and refilling with additive liquid of 
the second compartment, including the accompanying inconveniences, are 
eliminated. 
Another object of the present invention is an additive liquid introducing 
device using a disposable container with a plastic bag defining the first 
compartment receiving the carrier liquid, and a plurality of second 
compartments. Such a container is purchased with its second compartments 
filled with respective additive liquids to be simultaneously introduced in 
the carrier liquid, which additive liquids cannot be mixed beforehand. 
A further object of the invention is an additive liquid introducing device 
having means for easily and precisely adjust the quantity of additive 
liquid introduced by volume unit of carrier liquid. 
A seventh object of the present invention is an additive liquid introducing 
device which requires no maintenance. 
Another further object of the invention is to provide an additive liquid 
introducing device which is usable for an emulsion or suspension. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention relates to a device for introducing an 
additive liquid into a carrier liquid which is caused to flow in a main 
pipe, comprising a pipe section so connected with the main pipe that the 
carrier liquid flows in this pipe section, and a constriction formed in 
the pipe section and traversed by the carrier liquid. The carrier liquid 
is therefore under a first pressure upstream of the constrictions and 
under a second pressure lower than the first pressure downstream of the 
constriction. The additive liquid introducing device according to the 
invention further includes first tube means, a bag made of thin, flexible 
impermeable material, second tube means, and a quick-fit connector. The 
first tube means comprises (a) a first tube having a first end connected 
to the pipe section upstream of the constriction, and a second free end, 
and (b) a second tube having a first end defining a first orifice 
communicating with the inside of the pipe section downstream of the 
constriction, and a second, free end adjacent to the second end of the 
first tube. The bag defines an inner membrane which divides it into first 
and second compartments, the latter containing the additive liquid. The 
second tube means comprises (a) a third tube having a first end attached 
to the bag and communicating with the first compartment, and a second, 
free end, and (b) a fourth tube having a first end also attached to the 
bag and communicating with the second compartment, and a second, free end 
adjacent to the second end of the third tube. The quick-fit connector is 
provided with first connecting means mounted on the second ends of the 
first and second tubes, and second connecting means mounted on the second 
ends of the third and fourth tubes, which first and second connecting 
means being designed for simultaneous connection of the second end of the 
third tube with the second end of the first tube, and of the second end of 
the fourth tube with the second end of the second tube, as well as for 
simultaneous disconnection of the second end of the third tube from the 
second end of the first tube, and of the second end of the fourth tube 
from the second end of the second tube. 
In operation, the carrier liquid under the first pressure upstream of the 
constriction is transmitted in the first compartment through the 
interconnected first and third tubes to apply pressure on the additive 
liquid in the second compartment through the inner membrane, to thereby 
cause flowing of additive liquid from the second compartment through the 
interconnected second and fourth tubes and introduction thereof in the 
carrier liquid under the second pressure downstream of the constriction 
through the first orifice. 
In accordance with a preferred embodiment of the present invention, the bag 
is made of thin, flexible plastic and transparent material and the 
constriction is formed by a venturi positioned in the pipe section. In 
such a preferred embodiment, pressure limiting means are disposed in the 
first tube for limiting to a predetermined value the pressure of the 
carrier liquid in the first compartment by closing the first tube when the 
pressure of the carrier liquid in the first compartment reaches the 
predetermined value in order to prevent breaking of the bag, the first end 
of the second tube defines a second orifice communicating with the inside 
of the venturi so that, when the pressure limiting means closes the first 
tube, the increase in speed of the carrier liquid within the venturi 
produces in the constriction a depression which causes by aspiration 
flowing of additive liquid from the second compartment through the second 
and fourth tubes and introduction thereof in the carrier liquid through 
the second orifice. 
The bag, the second tube means and the second connecting means 
advantageously constitute a unit made of plastic material and disposed of 
after use. By means of the quick-fit connector, such a disposable unit can 
be easily replaced by a new one through a single disconnection-connection 
operation. 
The bag of the additive liquid introducing device according to the 
invention may be provided with a plurality of second compartments, 
containing different additive liquids, possibly of different 
concentrations. As all these second compartments communicate with the 
first end of the fourth tube, additive liquids from the second 
compartments can be simultaneously introduced in the carrier liquid. This 
is particularly useful when different medicaments which cannot be mixed 
beforehand must be introduced in the carrier liquid in different 
concentrations. 
In accordance with another preferred embodiment of the additive liquid 
introducing device according to the invention, the pipe section comprises 
two ends provided with means for removably connecting this pipe section 
with said main pipe. Easy transfer of the pipe section from one pipe to 
the other is thereby enabled. 
The objects, advantages and other features of the present invention will 
become more apparent upon reading of the following non restrictive 
description of a preferred embodiment thereof, given for the purpose of 
exemplification only with reference to the accompanying drawings in which:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1 of the attached drawings, the additive liquid 
introducing device according to the invention comprises a pipe section 1 
connected in series with a main pipe 2 in which the carrier liquid is 
caused to flow in the direction shown by the arrows such as 3. 
The confronting ends of the main pipe 2 are each provided with a threaded 
collar 4, 4', while the ends of the pipe section 1 are each provided with 
an outer flange 5, 5'. Two nuts 6, 6' are threaded on the inside and each 
provided with an inner flange slidably mounted around the pipe section 1. 
In order to mount the pipe section 1 on the main pipe 2, the user 
positions the pipe section 1 between the collars 4, 4' as shown in FIG. 1, 
with the nuts 6, 6' slid towards the center of the pipe section 1 and with 
two annular gaskets 8, 8' respectively positioned between the 
corresponding pairs of collar 4-flange 5 and collar 4'-flange 5'. The nuts 
6, 6' are then screwed on the threaded collars 4, 4', respectively. During 
screwing, the inner flanges of the nuts 6, 6' abut on the flanges 5, 5' so 
as to crush the gaskets 8, 8', respectively, thereby forming liquidtight 
joints between the collar 4 and the flange 5, and between the collar 4' 
and the flange 5'. The gaskets 8, 8' can be for example made of rubber. 
In order to remove the pipe section 1 from the main pipe 2, the user has 
only to unscrew the nuts 6, 6' and to slide them towards the center of the 
pipe section 1. The pipe section 1 is then moved laterally with respect to 
the main pipe 2. 
It can therefore be easily appreciated that, when flowing of water through 
the pipe 2 is interrupted by means for example of a valve, the additive 
liquid introducing device according to the invention can be easily mounted 
on and removed from the main pipe 2 through connection and disconnection 
of the pipe section 1 to and from the main pipe 2. Easy transfer of the 
additive liquid introducing device from one liquid pipe to the other is 
thereby enabled. The small dimensions of the additive liquid introducing 
device facilitate such transfer. After the pipe section 1 has been 
removed, flowing of water through the main pipe 2 can be enabled by 
mounting between the ends of the pipe 2 an ordinary pipe section provided 
with nuts such as 6 and 6', or by any other means. 
In some cases, it can be suitable to permanently connect the pipe section 1 
in series with the main pipe 2. In this case, the nuts 6, 6', the flanges 
5, 5', and the collars 4, 4' can be replaced by permanent connectors. 
The pipe section 1 is preferably made of substantially rigid plastic 
material and includes a venturi 9 disposed therein. The venturi 9 can be 
made integral with the pipe section 1 or formed by a separate piece of 
plastic material glued on the inner surface of the pipe section 1. 
As the carrier liquid flows in the pipe section 1, a difference in pressure 
is produced by the venturi. Indeed, the pressure of the carrier liquid 
upstream of the venturi 9 is somewhat higher than that downstream of this 
venturi. 
A tube 10 is connected perpendicular with the pipe section 1 upstream of 
the venturi 9. The tube 10, preferably made of substantially rigid plastic 
material, comprises an internal longitudinal protuberance, while the pipe 
section 1 is provided with an external longitudinal protuberance. In these 
two longitudinal protuberances is formed a small diameter tube 11. The 
tube 11 comprises a two-branched end which defines, by means of a tubular 
extension 12, a first orifice 13 communicating with the inside of the pipe 
section 1 downstream of the venturi 9. The tubular extension 12 may be 
integral with the pipe section 1 or glued on the inner surface thereof. 
The two-branched end of the tube 11 also defines a second orifice 14 
communicating with the inside of the constriction formed by the venturi 9. 
As illustrated in FIG. 1, the free ends 26 and 15 of the tubes 10 and 11, 
respectively, have increased internal diameters. 
The additive liquid introducing device further comprises a bag generally 
identified by the reference 16 which defines a first compartment 17 and a 
second compartment 18 separated from each other by a flexible, impermeable 
membrane 19. 
A tube 20 has a first end which communicates with the first compartment 17 
of the bag 16 and a second, free end 27 with a reduced external diameter 
which can be inserted in the end 26 with increased internal diameter of 
the tube 10. The reduced external diameter of the end 27 is therefore 
substantially identical to the increased internal diameter of the end 26. 
The tube 20 is also provided at its first end with an annular, flat flange 
21 perpendicular to the longitudinal axis of the tube 20. Again, the tube 
20 is advantageously made of substantially rigid plastic material. 
The bag 16 is made of thin, transparent flexible plastic material. A first 
layer of transparent plastic material, which constitutes the flexible 
impermeable membrane 19, is provided with a hole having a diameter 
corresponding to the inner diameter of the tube 20. The layer 19 is 
attached in the periphery of its hole on the flange 21 through a heating 
process. A second layer 22 of transparent plastic material has its 
periphery attached to the periphery of the layer 19 through the same 
heating process so as to form the first compartment 17 communicating with 
the first end of the tube 20. The bag 16 comprises a third layer 23 of 
transparent plastic material which includes a hole of diameter 
corresponding to the outer diameter of the tube 20 and has the periphery 
of its hole attached through the heating process to the flange 21 on the 
side opposite to the layers 19 and 22. The layer 23 has also its periphery 
attached to the periphery of the layer 19 by means of the heating process, 
so as to form the second compartment 18 of the bag 16 containing the 
additive liquid. 
The tube 20 is provided with an inner longitudinal protuberance in which a 
small diameter tube 24 is formed. The tube 24 extends through the flange 
21 to communicate with the second compartment 18 of the bag 16. The other, 
free end of the tube 24 comprises a tubular extension 25 dimensioned for 
insertion in the end 15 with increased internal diameter of the tube 11. 
The outer diameter of the extension 25 and the increased diameter of the 
end 15 of the tube 11 are therefore substantially the same. 
When the end 27 with reduced external diameter of the tube 20 is inserted 
in the end 26 with increased internal diameter of the tube 10, with the 
tubular extension 25 also inserted in the end 15 with increased internal 
diameter of the tube 11, a first 0-ring 28 (FIG. 2) preferably made of 
rubber material and inserted in an annular groove 29 formed on the 
external surface of the free end 27 of the the tube 20, as well as a 
second 0-ring 30 (FIG. 2) also made of rubber and inserted in an annular 
groove formed on the external surface of the tubular extension 25 ensure 
imperviousness of the joints between the ends 26 and 27 of the tubes 10 
and 20, and between the tubular extension 25 and the end 15 of the tube 
11. 
An annular retainer 31 integral with the tube 10 and made of somewhat 
elastic plastic material connects the tube 20 with the tube 10 and the 
tube 24 with the tube 11 by retaining the end 27 in the end 26 and the 
tubular extension 25 in the end 15, through abutment on of an annular 
collar 32 of triangular cross section. Upon connection of the tubes 20 and 
24 with the tubes 10 and 11, respectively, the tube 20 (with the tube 24) 
is pushed in the direction opposite to that of the arrow 34 to insert the 
end 27 in the end 26 and the tubular extension 25 in the end 15. The 
retainer 31 is then elastically deformed by movement of the collar 32 in 
the direction opposite to that of arrow 34. When the collar 32 is inserted 
in the retainer 31, connection between the tubes 20 and 10 and the tubes 
24 and 11 is completed. In order to increase the retaining strength of the 
retainer 31, a slidable annular cover 33 is slid along the tube 10 in the 
direction shown by the arrow 34 until the annular peak 36 of the retainer 
31 is positioned in the annular groove 35 in the inner surface of the 
cover 33. In order to disconnect the tube 20 from the tube 10 and the tube 
24 from the tube 11, the cover 33 is slid along the tube 10 in the 
direction opposite to that shown by the arrow 34, and the tube 20 is 
pulled in the direction of the arrow 34. The retainer 31 is then 
elastically deformed to allow removal of the assembly comprising the tubes 
20 and 24, and the bag 16. 
It can be appreciated from the above description that the ends 15, 26 and 
27, the tubular extension 25, the collar 32, the retainer 31 and the cover 
33 constitute a quick-fit connector allowing single-operation connection 
and disconnection. 
In operation, the carrier liquid upstream of the venturi 9 is transmitted 
in the compartment 17 of the bag 16 through the interconnected tubes 10 
and 20 as shown by the arrows such as 37. In order to prevent breaking of 
the bag 16 caused by a too high pressure of the carrier liquid in the 
compartment 17, a pressure limiting valve 38 is mounted within the tube 
10. When the pressure of the carrier liquid in the compartment 17 reaches 
a predetermined value, the valve 38 closes in order to limit the pressure 
of the carrier liquid in the compartment 17 to this predetermined value, 
which pressure value can be supported by the bag 16. 
When the valve 38 is open, as the pressure of the carrier liquid upstream 
of the venturi 9 is somewhat higher than that downstream of this venturi, 
pressure is applied by the carrier liquid in the compartment 17 on the 
additive liquid in the compartment 18 through the inner membrane 19 (see 
arrows such as 38). Additive liquid from the compartment 18 is therefore 
caused to flow in the tubes 24 and 11 and is introduced in the carrier 
liquid downstream of the venturi 9 through the orifice 13. The arrows such 
as 39 show that additive liquid from the compartment 18 is directed 
towards the end of the tube 24 by the action of the pressure (arrows 38) 
applied thereon through the membrane 19. 
When the valve 38 is closed to limit the pressure of the carrier liquid in 
the compartment 17, additive liquid from the compartment 18 is still 
introduced in the carrier liquid through the tubes 24 and 11 and the 
orifice 14. Indeed, flowing of the carrier liquid through the venturi 9 
creates a depression in the constriction formed in the pipe section 1, 
which depression aspirates additive liquid from the compartment 18 to 
introduce it in the carrier liquid through the orifice 14. 
When the carrier liquid in the main pipe 2 stops to flow, the pressure of 
the carrier liquid upstream, downstream and inside of the venturi 9 are 
the same and no additive liquid from the compartment 18 is introduced in 
the carrier liquid through the orifices 13 and/or 14. 
Preferably, the valve 38 is designed to close automatically when the 
assembly including the tubes 20 and 24 and the bag 16 is removed from the 
tubes 10 and 11 to prevent flowing of the carrier liquid out of the end 26 
of the tube 10. 
When the assembly including the tubes 20 and 24 and the bag 16 is removed, 
and the valve 38 is closed, carrier liquid from the pipe section 1 flows 
through the orifices 13 and 14, and the tube 11. Such flowing can be used 
to wash the tube 11. A closure of the tube 11 is also provided to prevent 
flowing of the carrier liquid at the end 15 thereof. Such closing is 
illustrated, by way of example, in FIG. 3 of the attached drawings, and is 
described in detail in the following description. 
The quantity of introduced additive liquid by volume unit of carrier liquid 
can be adjusted by appropriately selecting the diameter of the tube 11 
and/or of the tube 24. However, if the introduced quantity of additive 
liquid must be varied, a system for achieving such variation is mounted on 
the additive liquid introducing device. Such a system is illustrated in 
FIG. 3, and comprises a further external protuberance 40 at the 
intersection between the pipe section 1 and the tube 10 in the region of 
the tube 11. The protuberance 40 defines a cavity 41 in which is rotatably 
mounted a disk 42 through an axle 43. The periphery of the disk 42 is 
provided with a plurality of holes of different diameters such as 44. By 
rotating the disk 42, the hole 44 of suitable diameter can be aligned with 
the tube 11 so as to easily and precisely adjust the quantity of additive 
liquid introduced by volume unit of carrier liquid. Two 0-rings 45 assure 
imperviousness of the joints between the hole 44 and the tube 11. When the 
disk 42 is so positioned that a portion thereof with no hole 44 is aligned 
with the tube 11, the latter is closed and no carrier liquid can flow 
through the free end 15 of the tube 11 when the assembly including the 
tubes 20 and 24 and the bag 16 is removed. 
It can be easily appreciated from FIG. 1 of the attached drawings that the 
most costly pieces of the additive liquid introducing device are mounted 
on the pipe section 1 or tube 10. It is important because these pieces are 
reused and form a permanent assembly, while the assembly including the 
tubes 20 and 24 and the bag 16 is disposable. The device according to the 
invention is therefore designed to allow low cost manufacturing of the 
latter assembly. When the disposable assembly including the bag 16 is 
purchased with the compartment 18 filled with additive liquid, no 
refilling of the compartment 18 is necessary, no mixing of the additive 
liquid is required and therefore no contamination of for example a 
medicament constituting the additive liquid is possible. As the bag 16 is 
sold with its compartment 18 filled with additive liquid, a suitable 
closure member (not shown) may be associated with the tubular extension 25 
to prevent loss of additive liquid through the tube 24, and contamination 
of the additive liquid, for example when the latter is a medicament. 
As shown in FIG. 4 of the attached drawings, representing a cross sectional 
view of the bag 16 taken along the axis A-A of FIG. 1, the bag 16 may 
comprise the compartment 17 defined by the layers of plastic material 22 
and 19 and in communication with the corresponding end of the tube 20, as 
well as a plurality of second compartments 18, 18', 18" and 18'". Four 
compartments 18 are shown in FIG. 4, but the number of these compartments 
can be varied as required. The compartments 18 are defined by the membrane 
19, by the layer of plastic material 23 and by the partition layers 46 
also made of thin, transparent and flexible plastic material. The 
compartments 18, each tightly closed upon purchase can be opened by 
removing closure means (not shown) to communicate with the corresponding 
end of the tube 24, so that different additive liquids contained in the 
compartments 18 upon purchase can be introduced at the same time in the 
carrier liquid. The concentration of each additive liquid is adjusted as 
required so that appropriate amounts of the different additive liquids are 
injected in each volume unit of the carrier liquid. The embodiment of the 
bag 16 shown in FIG. 4 of the attached drawings is useful when a plurality 
of additive liquids which cannot be mixed beforehand have to be 
simultaneously introduced in the carrier liquid. 
It should be pointed out here that the dimensions of the membrane 19 and 
layers 46 have to be substantially the same as that of the layer 23 so 
that each of the membrane 19 and layers 46 can lay on the entire inner 
surface of the layer 23, as shown by way of example by the dashed-lined 
layer 47 in FIG. 4, in order to allow complete emptying of all the 
compartments 18. 
FIG. 5 illustrates a key system used in the connection of the disposable 
assembly to the permanent assembly of the additive liquid introducing 
device. As can be seen, the internal surface of the free end 26 with 
increased internal diameter of the tube 10 is formed with a predetermined 
pattern 48. Accordingly, the free end 27 with reduced external diameter of 
the tube 20 has an outer surface which defines the same pattern identified 
by the reference 49. Consequently, upon connection of the permanent and 
disposable assemblies of the additive liquid introducing device, the 
pattern 49 is inserted in the pattern 48. When inserting the pattern 49 
into the pattern 48, the tubular extension 25 is automatically and 
simultaneously inserted into the end 15 with increased internal diameter 
of the tube 11. Such a key system may, for example, prevent disposable 
assembly from another competitor manufacturer to be inserted in the 
permanent assembly of a certain manu- facturer. 
A pressure regulator 50 is mounted in the pipe section 1 upstream of the 
tube 10 and has as function to prevent excessive variation of pressure of 
the carrier liquid downstream thereof, so as to obtain a more precise 
quantity of introduced additive liquid by volume unit of carrier liquid. 
In some circumstances, it can be desired to increase the strength of the 
bag 16, so that the latter can resist to the pressure in the compartments 
17 and 18. A removable sheah 100 can be used for that purpose. Such a 
sheath 100 adapts to the external shape of the bag 16. The sheath 100 
comprises an upper opening 101 having dimensions suitable (a) to insert 
therein the bag 16 with the compartment 17 empty, but with the compartment 
18 filled with additive liquid, and (b) to remove therefrom the bag 16 
with its second compartment 18 empty. 
As can be appreciated, the sheath 100 can be used to reduce the thickness 
of the walls of the bag 16 in order to reduce the cost of manufacturing 
the above defined disposable assembly including the bag 16. 
An annular groove 102 is made in the upper, external wall 103 of the bag 
16, in which groove 102 is inserted an annular, internal protuberance 105 
provided on the inside of the upper wall 104 of the sheath 100. In order 
to give the required strength to the assembly, the upper wall 103 must be 
thicker than the rest of the bag. It can be appreciated that, when the 
protuberance 105 is inserted in the groove 102, the force produced by the 
pressure in the compartments 17 and 18 is applied to the sheath 100 and to 
the upper wall 103 of the bag 16 retained by the sheath through the set of 
annular groove 102 and protuberance 105. 
Of course, the end of the tube 20 of FIG. 1, which is attached to the bag 
16 should be modified to adapt to the bag and sheath assembly of FIG. 6. 
As an example, the upper wall 103 of the bag 16 may comprise the flange 21 
of the tube 20 appropriately shaped and made of flexible plastic material. 
The other required modifications are believed to be within the knowledge 
of one skilled in the art and for that reason, they will not be further 
elaborated. It must however be kept in mind that the principle of 
operation and the other characteristics of the additive liquid introducing 
device of the invention must remain the same. 
Some uses of the additive liquid introducing device of the invention are 
the following: 
introduction of a chlorine solution in the water when the water filtration 
system of a residential house is out of order, thereby preventing illness 
risks due to contamination of the water; 
automatic introduction of liquid soap and/or liquid fabric softener in 
required amounts (without loss) in the water used to wash clothes; 
introduction of medicaments in the water to be drunk by living stock; 
introduction of a sweetened solution in the coffee served by automatic 
vending machines; 
automatic introduction of a liquid disinfectant in the water supplied to 
toilets; 
injection of a liquid water softener in the water supplied to a dishwasher; 
and 
introduction of precise, small quantities of various solutions in liquids 
used in industrial processes. 
etc . . . 
Although the present invention has been described hereinabove by way of a 
preferred embodiment thereof, it should be pointed out that any 
modification to such a preferred embodiment within the scope of the 
appended claims, is not deemed to change or alter the nature of the 
present invention.