GB2431439A

GB2431439A - Volumetric dosing apparatus

Info

Publication number: GB2431439A
Application number: GB0521341A
Authority: GB
Inventors: Edward William Coulson
Original assignee: CCL Concept and Developments Ltd
Current assignee: CCL Concept and Developments Ltd
Priority date: 2005-10-20
Filing date: 2005-10-20
Publication date: 2007-04-25
Also published as: WO2007045926A1; EP1937972A1; GB0521341D0

Abstract

A dosing apparatus comprises a substantially rigid housing 2, 3 including a void 4, 5 a disposable element including a first bladder 7 located in the housing and having an inlet 13 and an outlet 12 and a one way valve 14, 15 associated with each of said inlet and outlet, and means for increasing and decreasing the volume of the first bladder increasing and decreasing the volume of the first bladder causes fluid to be drawn into the first bladder through the inlet and to be expelled from the first bladder through the outlet. A substantially constant vacuum is exerted between inner surface of the void and the outer surface of the first bladder. The means for increasing and decreasing the volume of the first bladder may be a second bladder 6.

Description

* 2431439 Volumetric Dosing Unit

Field of the Invention

This invention relates to the dosing and transferring of fluids and in particular to a dosing unit capable of consistently dosing desired volumes of fluid accurately, where the fluids passing through the pump are contained within inexpensive, disposable parts that may be received in either a clean, or pre sterilised condition.

Background of the Invention

One system employed for supplying controlled volumes of sterile fluids, principally during bypass surgery, involves the use of a pump comprising a bladder connected to a fluid to be pumped, the bladder being expandable and compressible to suck in and push out sterile fluid. Examples of this type of systems are described below: US 4116589 describes a system for pumping blood when patient is having heart bypass surgery. The system has two bladders, one in the blood supply line and one in a vacuum line. The vacuum is applied and released, which expands and contracts the bladder connected to the blood supply, thereby pumping the blood.

US 3,895,741 describes a dosing system for introducing fluid intravenously into a patient. A bladder filled with the fluid to be introduced is located in a housing between a solid surface and an inflatable bag. When the bladder is in fluid connection with the vein of a patient, the pneumatic pressure in the inflatable bag is set to a level matching a desired pressure of the fluid. The whole device is located above the patient and serves to assist gravity in expelling the fluid from the bladder.

jP09109339 describes a housing in which a bladder is located. As pressure in the housing rises and falls so does the size of the bladder, which includes two non-return valve, one being an inlet and the other an outlet.

The non-return valves open according to whether the pressure in the box is rising or falling.

US 5273406 describes a pump comprising three or more flexible bladders, each mounted in an inflexible tube. A pneumatic controller distributes a predetermined pattern of pressure and vacuum pulses between the inside of the tube wall and the flexible liner to pump fluid. [he effect is to pump fluid through the pipe.

WO 03/101883 describes a pump used in merchandising, i.e. making and dispensing drinks. Fluid is pumped by sequentially applying a vacuum and positive air pressure to expand and contract a flexible liner located in a cavity.

lnjP09l09339 a liner is contained in a rigid shell. Fluid is transferred by applying a vacuum to one side of the liner while pressure is applied to the other side thereof. The liner is described as being easily replaceable.

The most common pumping system that contains the product in disposable contact parts is the peristaltic pump, but this pump suffers from another range of disadvantages such as loss of accuracy during production, slow filling rates per pump head, and where accurate filling is sought, small volume fills per head.

Summary of the Invention

According to one aspect of the invendon there is provided a dosing apparatus as specified in Claim 1.

According to a second aspect of the invention there is provided a disposable element as specified in Claim 20.

According to a third aspect of the invention there is provided a method of dosing a fluid as specified in Claim 21.

The applications envisaged for the invention are mainly industrial: i) The syringe pump version of the patent for medium to high speed repetitive filling on production line of tubes, ampoules, vials, bottles, jars, syringes, aerosols, and other containers with an additional medical use, the pumping of blood during heart operations; ii) The mechanically driven and hydraulic diaphragm pump versions of the pump for industrial metering of products during the formulation and mixing stages; and iu**) Fhe pneumatic diaphragm pump versions of the pump arc used for simple product transfer from vessel to vessel, or on demand from vessel to machine where accurate dosing is not an issue - this type of pump can be simplified in that the vacuum gauge and external means of supplying the vacuum may be eliminated in certain circumstances, but as for all the above, has the advantage of disposable (also prc-steriliscd contact parts.

Brief Description of the Drawings

In the drawings, which illustrate preferred embodiments of a volumetric dosing unit, and are by way of

example:

Figure 1 is a schematic representation of a first embodiment of a volumetric dosing unit according to the invention, in a non-working configuration; Figure 2 is a schematic representation of the volumetric dosing unit illustrated in Figure 1, in a working con figuration; Figure 3 is a schematic representation of a second embodiment of a volumetric dosing unit according to the invention; Figure 4 is a schematic representation of an element of the volumetric dosing unit illustrated in Figure 3; Figure 5 is a schematic representation of a volumetric dosing unit according to a third embodiment of the invention; Figure 6 is a schematic representation of a volumetric dosing unit according to a fourth embodiment of the invention; Figure 7 is a schematic representation of a volumetric dosing unit according to a fifth embodiment of the invention; Figure 8 is a schematic representation of a volumetric dosing unit according to a sixth embodiment of the iflvcnon; Figure 9 is a schematic representation of a first embodiment of a pinch valve; and Figure lOis a schematic representation of a second embodiment of a pinch valve.

Detailed Description of the Preferred Embodiments

Referring now to Figures 1 and 2 of the drawings there is illustrated a volumetric dosing unit 1 comprising a shell element 2 and a second shell element 3, which are joined together, in the example by a hinge at 3a. Each shell includes a recess 4, 5 which align when the shell elements 2, 3 are brought together and form a sealed chamber. First and second bladders 6, 7 are located within the chamber and are subjected to a negative pressure as a result of a vacuum being applied to the chamber. f'he vacuum is applied to the chamber via a bore 16 through the second shell element 3 and a pipe 17 connected to a vacuum gauge 18 and one way valve 21. A vacuum from an external source is applied to the one way valve 21. The first bladder 6 has an inlet 9 that is connected to a pumping fluid 11 which is contained in a new or existing syringe pump 10. 1'he second bladder 7 is connected by a pipe 8 to an inlet pipe 13 via a first valve 14, and to an outlet pipe 12 via a second valve 15.

lhe vacuum pressure applied to the chamber by the external negative pressure source through valve 21 is set above a minimum level on gauge 18 and serves to pull the surfaces 19, 20 of the bladders 6, 7 respectively against the respective surfaces of the recesses 4, 5. The bladders 6,7 are identically sized, and the shape and configuration of the sealed chamber matches exactly the shape and size of either of bladders 6,7 when one of said bladders is completely filled. The second bladder 7 communicates with a supply of fluid to be pumped by means of the tubes 8 and 13, and the inlet valve 14. The fluid may be for any uses mentioned herein, including an intravenous drug or a pharmaceutical product to be dispensed to a receptacle for example. The inlet valve 14 permits flow of fluid from the pipe 13 towards the pipe 8 and prevents flow in the opposite direction. The second bladder also conimunicates with the pipe 12 via a valve 15 via pipe 8. lhe valve 15 permits flow of fluid from the pipe 8 towards the pipe 12, but prevents the flow of fluid from pipe 12 towards pipe 8.

Fluid is pumped from the fluid supply pipe 13 to thc fluid outlet pipe 12 in the following manner As the first bladder 6 is expanded fluid contained in the second bladder 7 is forced out of the pipe 8, through the valve 15 and into pipe 12 from where it is dispensed.

As the first bladder 6 is contracted, the vacuum to which the chamber is subjected causes the second bladder 7 to expand. Negative pressure within the second bladder causes fluid to be drawn into the second bladder 7 through the pipe 13, non-return valve 14 and pipe 8.

The volume of fluid moved by the second bladder 7 corresponds to the volume of fluid 11 introduced and removed from the first bladder 6 by means of the piston lOa sliding in the syringe pump 10.

A controller (not shown) is provided to the syringe pump 10 to cycle the desired volume of the fluid into and out of the first bladder 6. lhe fluid 11 is incompressible, the first and second bladders 6, 7 are of the same dimension, and the external shape and configuration of each bladder 6, 7 matches the internal shape and configuration of the chamber formed by the shell elements 2, 3 thereby ensuring that the volume of fluid 11 moved into and out of the first bladder 6 exactly corresponds to the volume of fluid dispensed by the second bladder 7.

The second bladder 7, pipes 8, 12 and 13, and valves 14 and 15 comprise a disposable (sterile) element.

As mentioned above, the first and second shell elements 2, 3 may be joined together by a hinge 3a allowing the shells to be separated easily to facilitate removal of the second bladder.

Figures 3 and 4 illustrate another embodiment of a volumetric dosing unit in which a disposable element including non-return valves 31 and 32 is located in a housing 33 which includes outer casing elements 34 and 34', the element 34' being removably attachable to the element 34. By removing the outer casing element 34' the disposable (stenle element 30 may be removed and replaced. The casing element 34' includes a connector 39 for attachment to a source of negative pressure, the connector passing through the internal surface of element 34' designated 35' so that a vacuum can be applied between the internal surfaces of 35, 35' and the external surfaces of the disposable element 30.

The inner surfaces 35,35' of each casing element 34, 34' are extended outside casing elements 34,34', to form openings 34a. The inner surface 35 includes an opening 36 which is covered by a diaphragm 37. A piston 38 acts on the diaphragm 37 to move wall 30c towards and away from wall 30d. When the wall 30c is moved away from wall 30d, fluid is drawn from a fluid supply through the non-return valve 32 into the chamber 41 of the disposable element 30, the non-return valve 31 being closed by virtue of a negaiive pressure being created in the said chamber which draws the ball 31a of the non-return valve 31 against its seat 31b. When the piston 38 pushes the wall 30c towards the wall 30d, the ball 32a of non-return valve 32 is pushed against its seat 32b to prevent back flow of fluid to the supply, whilst the increased fluid prcssure in the chamber 41 lifts ball 31a off its seat 31b to allow fluid to flow through outlet 30a. As can be seen from Figure 4, the disposable (sterile) element is provided with integral seals 42, which in use sit between the outside of the element 30 and a sealing surface located on the inside of surfaces35, 35' io maintain the applied vacuum between inner surfaces 35, 35', diaphragm 37 and the disposable (sterile) clement 30.

The demonstrated vacuum sealing system is only one example of sealing systems that may be employed to maintain the vacuum.

The embodiment illustrated in Figure 5 is similar to that shown in Figure 3 (and like numerals are used to indicate like parts) except that instead of the diaphragm pump and piston 38 acting on diaphragm 37, the actuation of diaphragm 37 is made hydraulically from a small bore syringe pump 45thc wall 30c being moved towards and away from the wall 30d of the disposable element by diaphragm 37 into which a driving fluid 44 is introduced and removed by means of a syringe 45 comprising a piston mounted in a cylinder.

The embodiment illustrated in Figure 6 is very similar to that illustrated in Figure 5 but uses pinch valves instead of ball valves. The embodiment of Figure 6 comprises a two-part casing including a first part 50 being removably attached to a second part 52. Each nf the first and second parts 50, 52 include a wall 51 and 53 respecdvely which face each other and between which a disposable (sterilc element 58 is located. The second part 52 together with a diaphragm 60 forms a chamber 52' into which an incompressible fluid 54 is introduced and removed by a syringe 55 comprising a piston 56 which is slidably mounted in a cylinder 57. A connector 61 is attached to a vacuum source so that the outer surface of the part of the disposable element 58 located in the casing is subjected to a vacuum. Fluid to be pumped is drawn into and expelled from the disposable (sterile) clement 58 by movement of the piston 56 towards and away from the said disposable (sterile) element 58. The flow of fluid into and out of the disposable (sterile) element is controlled by the synchronization of the pinch valves 63 and 64. In Figure 6, the lower pinch valves 64 are closed. Their action is simply to press together the walls of the disposable (sterile) element 58 to provide a closure 65. Fluid cannot be drawn into the element 58.

The upper pinch valves 64 are open allowing fluid contained in the element 58 to be pumped downstream, for example to a product container. The amount of fluid that is pumped downstream corresponds to the volume of fluid introduced and removed from the chamber 52' by the syringe 55. A controller (not shown) co-ordinates the opening and closing of the pinch valves 63, 64 by mechanical means or by means of a servo-motor. l'he opening and closing of the pinch valves is also co-ordinated with the movement of the piston 56 of syringe 55. The controller is also connected to the vacuum monitor 62. If the vacuum fails the drive to the syringe pump 55 is stopped thereby preventing accidental inaccurate dosing from the unit. This fail safe mechanism can be used in each version of the unit.

I'he embodiment illustrated in Figure 7 is similar to that illustrated in Figure 5, (like numerals are used to indicate like parts) except that the syringe pump 70 comprises a bore 73 through which fluid from the cylinder 71 is pumped by piston 72 into a primary bladder 74, which is removably attached to bore 73 by a bladder neck and bore nipple (not shown). The primary bladder 74 replaces the diaphragm 37 with the advantage of being replaced more easily than a sealed diaphragm.

Referring now to Figures 6, 9 and 10, pinch valves are often substantially circular in cross-section 80.

Such pinch valves when used with plastic tubing 81' result in a small contact area 81 of the pinched tubing 81' and leave areas 82 of tubing 81' without dimensional control or support, which in turn may lead to inaccurate product doses should the tubing elasticity be changed during production by the constant flexing of said tubing 81'. The crosssectional shape of the pinch valves 63, 64 and 90 illustrated in Figures 6 and 10 respectively provide the following improvements. The contact profiles 91 between the pinched elements 91' are designed to follow the natural squeezed profile of tubing 81' so that the region 92 of the pinched element immediately to either side of the contact area 91 is supported against the surface of the pinch valve giving consistent and greater accuracy of dose, whereas a circular cross-section gives risc to unsupported area 82 of the pinched tubing 81' being inconsistently deformed leading to inaccuracies of dose.

Figure 8a illustrates a pump 100 the width of which has been niinimised to permit the pump's use with existing filling equipment. The pump comprises a first block 101 including a first cavity 101' in which a primary bladder (or diaphragm) 103 is located. Expansion and contraction of the primary bladder (or diaphragm) 103 is by virtue of fluid introduced into and removed therefrom by a syringe pump comprising a piston rod 106 and piston 107 that slides in a cyhnder (not shown) to pump fluid into and out of the primary bladder (or diaphragm) via aperture 105. A second block 102 is removably connected to the said first block 101 by means of a hinge or other suitable attachment means. The second block 102 includes a cavity 104 in which a disposable (sterile) element 110 is located, the said element comprising a secondary bladder an inlet valve 110 and an outlet valve 111. The inlet valve connects to a fluid supply 109 and the outlet valve 111 connects to an outlet pipe 108, which may for example deliver fluid to a product container.

lhe pwnp of the present invention provides a simple solution to accurately dosing a product. Where sterility is required this is achieved by ensuring that the fluid to be kept sterile does not come into contact with any part of the apparatus other than those pre-sterilised elements that arc disposable. These elements include the valves that control the flow of fluid into and out of the sterile bladder. Whereas the prior art relies on using varying levels of vacuum or pneumatic pressure, the present invention uses a static vacuum simply to hold the walls of the bladder(s) against the walls of a cavity. Inflation and deflation of the bladder of the sterile element is achieved by a diaphragm acting directly on the bladder, or by another bladder, the inflation and deflation of which respectively forces fluid out of and draws fluid into the sterile bladder.

The apparatus can be used as follows: in pharmaceucals to dose vials, bottles, jars, syringes, ampoules, sachets, tubes and other containers; in cosmetics lx) dose components into all manner of containers, including dosing aerosols; to dose sterile, Intravenous, toxic or other hazardous substances; and dosing of products where disposal of contaminated contact parts is simpler than cleaning of components, for cxample in the adhesive, DrY, food, drinks and dairy industries.

Furthermore, the pump of the invention could be used to pump blood in heart bypass surgery, the adjustable pulsing rhythm of the device being advantageous over peristaltic pumps in simulating the rhythmic pulse of the heart.

Ihere are many uses of the proposed puxnp not only for sterile and intravenous products, but also where the fluid is simply coloured, flavoured or scented, abrasive, potent, or simply difficult to clean from pump contact Parts. The pump of the invention can also be usefully employed in pumping or dosing some blood products and other fluids prone to sheering when pumped by syringe style pumps.

Claims

Claims 1. Dosing apparatus comprising a housing including a void, a

disposable element including a first bladder located in the housing and having an inlet and an outlet and one way valve means associated with each of said inlet and outlet, means for increasing and decreasing the volume of the first bladder, wherein increasing and decreasing the volume of the first bladder causes fluid to be drawn into the first bladder through the inlet and to be expelled from the first bladder through the outlet, and wherein a substantially constant vacuum is exerted between n inner surface of the void and the outer surface of the first bladder.
2. A dosing apparatus according to Claim 1, wherein the means for increasing and decreasing the volume of the first bladder comprises a second bladder located in the void and means for increasing and decreasing the volume of the second bladder, wherein increasing and decreasing the volume of the second bladder respectively decreases and increases the volume of the first bladder.
3. A dosing apparatus according to Claim 2, wherein the second bladder is filled with an incompressibic fluid.
4. A dosing apparatus according to any of Claims 2 or 3, wherein the volume of fluid moved through the first bladder corresponds to the change in volume of second bladder.
5. A dosing apparatus according to any preceding claim, wherein the shape and configuration of the inner surface of the void matches the shape and configuration of a respective one of the first and second bladders located within the void when inflated.
6. A dosing apparatus according to Claim 1, wherein the means for increasing and decreasing the volume of the first bladder comprises a diaphragm engaging with a surface of the first bladder and means to move the diaphragm to cause an increase and decrease in volume of the first bladder.
7. A dosing apparatus according to any preceding claim, wherein the means for increasing and decreasing the volume of the first bladder comprises a piston and cylinder. l0
8. A dosing apparatus according to Claim 6 or 7, wherein an actuator acts on the diaphragm to cause movement thereof to increase and decrease the voiume of the first bladder.
9. A dosing apparatus according to any of Claims 6 to 8, wherein the diaphragm is acted Ofl by an incompressible fluid.
10. A device according to any preceding claim, wherein the disposable element is sterile.
II. A device according to any preceding claim, further including a controller, wherein the controller commands operaon of the dosing apparatus.
12. A device according to Claim 11, wherein a vacuum monitonng means provides an input signal representative of the vacuum in the void to the controller and if the vacuum falls below a threshold the dosing apparatus is disabled.
13. A device according to Claim 12, wherein the controller enables the dosing apparatus when the detected vacuum rises above a threshold.
14. A device according to Claim 11, further comprising a moisture detector which provides to the controller an input signal representative of moisture content within the void and if the moisture content is above a threshold the dosing apparatus is disabled.
15. A device according to any preceding claim, wherein the disposable element includes valve means, the valve means providing for introduction of fluid into the first bladder when the volume thereof is increased and removal of fluid from the first bladder when the volume thereof is decreased.
16. A device according to Claim 15, wherein the said valve means comprises two non-return valves.
17. A device according to Claim 15, wherein the said valve means comprises a pair of pinch valves.
18. A device according to Claim 17, wherein the said pinch valves are servo operated.
19. A device according to Claim 17 or 18, wherein operation of the pinch valves is commanded by the controller.
20. A disposable element suitable for use with a device as claimed in any of Claims I to 19.
21. A method of dosing a fluid comprising the steps of: i) connecting the inlet of the disposable sterile element of a dosing apparatus as claimed in any of Claims I to 19 to a supply of sterile fluid; ii) connecting the outlet of the disposable clement of dosing apparatus to a dosing target; and iii) operating the said dosing apparatus.
22. A dosing apparatus substantially as shown in, and as described with reference to, the drawings.