Containers for solids which are to be dissolved in a liquid

Abstract: A container (16) for a solid to be dissolved in a liquid has inlet (25) and outlet (27) orifices at each end of its main chamber (21) centrally in the end walls (22,23) of that chamber which are truncated cones. Webs (33,34) have apertures by which the container be suspended in either vertical orientation. The inlet and outlet connections (32,27) to and from the container are at one end thereof.

Description: This invention relates to containers for solids which are to be dissolved in situ in a liquid. The containers in question are those which are to be used on apparatus which requires continuing supply of the solution formed. A particular example is a dialysis machine where it is difficult to use a previously prepared solution because of the need to maintain it free of micro-organisms. In EP-A-0278100 a dialysis machine is shown which has a detachable container or cartridge which has an inlet at one end and an outlet at the other, and which is to be received between two end brackets of the machine respectively containing the liquid inlet and the liquid outlet. A principal disadvantage of such cartridge is that its loading onto and off the end brackets is clumsy and time-consuming and almost inevitably in the unloading involves the loss of quantities of solution from the cartridge. Also there is no possibility in such an arrangement of a manoeuvre which is desirable in some aspects of the operation of a dialysis machine, namely the short circuiting the liquid flow by simply connecting inlet to outlet directly without the interposition of the container. The present invention aims to provide a container particularly adapted to deal with the problems of the efficient formation of a solution upon liquid flow through it, the utilization of the maximum amount of the charge of solid, and to allow for the use of inlet and outlet pipes at one end of the container so that couplings from the machine may be available for short circuiting if desired. We are aware of EP-A-475 825 claiming an earlier priority of 13 September 1990, which shows a container for a solid to be dissolved in situ in a liquid wherein both inlet and outlet are at one end of the container but are at opposite ends of a chamber for containing the solid. The present invention is distinguished by a tubular duct connecting one of the liquid inlet and outlet to an orifice in a central portion of the opposite end of the chamber of the container, the tubular duct being outside the chamber and joined integrally to an outer surface of its wall. The chamber of the container is preferably substantially circular in cross-section. The duct is also preferably generally circular or oval in cross-section. In a particularly preferred embodiment the end wall of a circular cross-section chamber of the container which surrounds the centrally disposed orifice slopes part-conically towards that orifice over at least part of that surface but preferably for the whole of it. In this way, "dead" pockets of solid which are relatively unaffected by liquid flowing through the container are partially or completely eliminated. It is even more preferable that both of the end surfaces of the main chamber of the container shall have that conical characteristic. Then, the container may be used in either vertical orientation, that is to say to permit the alternative of locating the inlet and outlet at the bottom end of the container. Preferred angles of slope are in the range 20° to 55°, more preferably 30° to 45°, to the normal to the major axis of the container which axis passes through the ends of the container. At the end of the container which is devoid of either inlet or outlet to the outside, there is preferably a cross-web formed outside the chamber. This may be used for standing the container stably on a relatively horizontal surface. The inlets and outlet will preferably have connection portions which are respectively different so as to prevent inadvertent wrong coupling of fluid inlet and outlet conduits from the machine with those connecting portions. The connecting portions are preferably complementary to each other so that corresponding connecting portions from inlet and outlet conduits will also be respectively complementary and the inlet and outlet conduits can therefore be coupled together when desired to short circuit the container. Inlets and outlets are preferably also designed to prevent recharging of the container which in the medical context could be highly dangerous. For this purpose, one of the inlet and the outlet has a comparatively wide neck plugged by a collar welded or otherwise permanently bonded to that neck and defining a comparatively narrow connection portion. The collar is adapted to be welded to the neck by some method, e.g. ultrasonic welding, which will not affect the contents of the container which have previously been charged into the container through the comparatively wide neck. Particular embodiments of the invention are described with reference to the accompanying drawings wherein: Figure 1 is a section through a median plane of a first embodiment of the invention; Figure 2 is a side view on the embodiment of Figure 1; Figure 3 is a diametrical section through a second embodiment; Figure 4 shows a detail of an outlet assembly and coupling from an outlet conduit; and Figure 5 shows a detail of the inlet conduit and coupling. In the first embodiment, a container 1 has a main chamber 2. At its upper end 3 is a liquid outlet 4 and an inlet 5. The chamber 2 is to contain a solid which is to be dissolved in a liquid which is to enter through the inlet 5 and leave as a solution through the outlet 4. The inlet 5 leads to a tubular duct 6 which proceeds all the way down one major side of the container and under a portion 7 of the floor of the container to emerge at an orifice 8 which is in a central portion, preferably exactly central, of the lower end 9 of the chamber. The duct 6 is formed integrally with a side wall 10 of the chamber of the container, being joined to it by a web. A web 11 also unites the inlet 5 and outlet 4 and contains an aperture 12 which is to allow the container to be hung from a hook or the like. To define the orifice 8 and give the duct 6 a vertical orientation where it passes into the orifice; one portion of the floor of the chamber at the end 9 is gathered into a web 13. The web 13 is at a level slightly above that of the base of the duct 6 where it underlies the floor portion 7 and of two portions 15 of the floor of the extreme end 9 of the container which lie to each side of it as seen in Figure 2, so that the container can be stood on a generally horizontal surface contacting those three areas. A collar 40 to be described in more detail later is permanently fitted to a neck 14 of the outlet 4 and this provides a connection portion for that outlet. A connection portion 32 for the inlet 5 is also to be described in more detail later. In one specific embodiment, the neck 14 may be unconnected to the web 11 over part or all of its length. All of the container except for the collar is preferably formed integrally by a blow-moulding technique, using (for medical applications) a pharmaceutically approved material such as high density polyethylene. Also, the containers may have to resist quite high excess pressures, of the order of 30 psi (207 kPa) when coupled to dialysis machines. After formation, the requisite solid is charged through the wide neck of the outlet 4 and then the collar is welded for example by ultrasonic welding to that neck. The comparatively narrow connection portion of the collar prevents for all practical purposes the recharging of the container with solid after it has been used. In use, the container is brought to the dialysis or other machine and a solvent liquid conduit from that machine is coupled to the inlet 5, a solution take-off conduit to the machine being coupled to the outlet 4. The collar itself, or the solution outlet, may include a filter: though one of the advantages of the construction of this container is that a filter is rendered less necessary than in the prior art because since the solution is rising, any solid impurities or undissolved particles will tend not to be carried into the outlet stream but rather to fall back and settle. A further advantage of this type of container is that since the inlet and outlet are both at the same end, and during coupling up or uncoupling from the machine this is the vertically uppermost end, there is no question of spillage or wastage during either operation. It is of course also possible to operate the container with the connections reversed, ie. with the solution being taken from the bottom outlet 8, which would ensure that gas would not escape with the outlet flow. In such an arrangement, preferably a solids filter is placed in the bottom of the container adjacent to and screening the outlet 8. A second and much more preferred embodiment is shown in Figure 3. The container 16 of Figure 3 is shown in an upright condition suitable for use, with its major axis 17 vertical. The container 16 has a receptacle which has a cylindrical main chamber 21 terminating in truncated conical end portions 22,23 which taper towards an inlet 25 and an outlet 27. The end portions 22,23 are angled to the normal to the axis of the cylinder by about 40°. The inlet 25 and outlet 27 in the end portions 22,23 are positioned at the major axis 17 of the container 16. The outlet 27 has a neck 28 extending therefrom which is coaxial with the major axis 17. The neck 28 has an annular rib 29 on its outer surface. A tube 30 extends from the inlet 32 alongside the first end portion 23 and then alongside the cylindrical main chamber 21 of the receptacle and parallel to its axis. The end portion 31 of the tube 30 which debouches into the inlet 25 is directed so as to cause inflowing liquid to flow generally parallel to the major axis 17 of the container. The tube 30 has a connection portion 32 which is laterally spaced from the neck 28 and parallel thereto. This end portion 32 is internally tapered and has an external thread. Alternatively there is annular ribbing. The container 16 has a supporting web 33 which connects the neck 28 to the tube 30. The web 33 also extends on the far side of the neck 28 from the tube 30. A supporting web 34 also extends from the lower end of the container 16 to form part of a base 35. A projection 37 extends downwardly from one end of the web 34 to provide a foot. A plate 39 is connected perpendicular to the web 34, the plate 39 having projections 19 at its end portions which provide second and third feet for the base 35. Holes 18 are provided in the webs 33,34 respectively for suspending the container. The neck 28 and open end portion 32 of the tube 30 extend upwardly beyond the web 33. The supporting webs 33,34 are formed at a central plane between two halves of the container when the container is formed by blow moulding and/or compression moulding. The cylindrical form of the chamber is particularly preferred as being the strongest for resisting pressure. Prior to use, the required amount of granular or powder-form concentrate substance is inserted into the chamber via the wide neck 28 of the outlet 27. The neck 28 being central is advantageous in this stage of production in that it facilitates easy alignment of containers on production-line conveyor belts for insertion of the concentrate substance. The chamber of the container generally has a free space of some 5 to 30% (and preferably 10 to 25%) of the total container volume after insertion of the concentrate substance. After insertion of the concentrate substance, a collar and optionally a filter may be inserted into the neck 28. A collar 40 which is suitable for insertion in the neck 28,14 of either embodiment is shown in Figure 4. The collar 40 has a tapered outer surface 42 for tight connection in the neck 28,14 of the container. A flange 43 projects outwardly from the outer surface of the collar 40 for abutment with the end of the neck 28,14. A ridge 44 projects from the flange 43. The collar 40 may be sealed in the neck 28,14 by ultrasonic welding, which provides seals both between the flange 43 and the end of the neck 28,14 and between the internal surface of the neck 28,14 and the external surface 42 of the collar 40. The ridge 44 is melted during this welding process. The collar 40 has a central spigot 46 extending axially thereform. The spigot 41 is tapered for tight connection of a flow-line. A conduit 49 passes axially through the collar 40 and forms the outlet from the chamber. There is an internally threaded or ribbed socket 48 extending in axial alignment with and surrounding the spigot 46. The socket 48 is arranged to cooperate with a connection member 50 from a flow-line such as is shown in Figure 4. The connection member 50 of Figure 4 has an external thread or ribbing on a first end portion 52 thereof. The first end portion 52 is tapered internally to form a fluid-tight seal with the spigot 46 of a collar as shown in Figure 3 when the collar 40 and the connection member 50 are threadedly or frictionally engaged. The connection member 50 has an outwardly extending shoulder 54 from which projects a cylindrical pipe 56 in axial alignment with the tapered first end portion 52. An axial conduit 58 passes through the connection member 50. A fluid line will be attached to the cylindrical pipe 56. The collar 40 and connection member 50 thereby provide male and female members of which the respective interconnectable portions are complementary. A connection member 60 is shown in Figure 5 which has a tapered spigot 62 for fluid tight abutment with the tapered end portion 32 of an inlet tube of a container according to the present invention. Preferably the tapered connection is so dimensioned as not to be compatible with similar liquid connections used for other medical purposes, such as for conveying intravenous products. A cylindrical pipe 64 extends axially from a shoulder 66 at one end of the spigot attachment of a fluid-line from the machine. A continuous fluid conduit 68 passes axially through the pipe 64 and spigot 62. An internally threaded or ribbed cap 68 surrounds the spigot with an annular end plate 70 arranged for abutment against the shoulder 66. The pipe 64 extends through the end plate 70 when the connection member 60 is assembled for connection to the connection portion 32. When the cap 68 threadedly engages the end portion 32, the spigot 62 is forced into the end of the tube 6,30 to provide a fluid-tight seal. The fittings of the connection members 50,60 are complementary; thus if it is desired to short-circuit the container the members 50,60 may simply be coupled together. The container may be used just as the first embodiment was, with the end surface 22 lowermost and with liquid flowing upwardly in the chamber. The conical form of the surface 22 reduces or eliminates any dead volumes where there is inefficient contact between solid and liquid. In this mode of use, the presence of a filter within the collar is not essential, though operators may prefer nevertheless that one shall be present. This container may also be used inverted, that is with end 23 lowermost and end 22 uppermost. Then, presence of a filter such as a known thimble filter 47 is essential, the thimble 47 being fitted as part of the collar and nesting within an end portion of the collar. An advantage of this mode of operation is that any gas bubbles formed will rise towards the (now uppermost) liquid inlet orifice 25 and remain there, and in the now uppermost part of the conical end 22, harmlessly.

Claims: A container (1,16) for a solid which is to be dissolved in situ in a liquid having a chamber (2,21) to be charged with the solid, the chamber (2,21) having respective inlet and outlet openings (8,14,25,27) at opposite ends of the container, respective external connections (4,5,29,32) for said openings at one of said ends of the container, a tubular duct (6,30) outside the chamber and joined integrally (10,33) to an outer surface of a wall of the chamber providing communication between one (5,32) of the said external connections and the opening (8,25) at the opposite end of the container. A container according to claim 1 wherein the chamber (2,21) is circular in cross-section. A container according to claim 2 wherein the opening (8,25) communicating with said tubular duct (6,30) is located in a central portion of its end of the chamber. A container according to claim 3 wherein the end wall (22) of the chamber surrounding the central opening (25) is at least partly conical to slope towards said opening. A container according to claim 2, claim 3 or claim 4 wherein the opening (27) at the end of the chamber opposite to the end communicating with said duct is a centrally located opening and the surrounding end wall (23) of the chamber is at least partly conical to slope towards said opening. A container according to any one of the preceding claims wherein the tubular duct (6,30) is marginally disposed, and a web (11,33) joins the duct (6,30) to a neck (14,28) extending from the opening at that end of the chamber. A container according to any one of the preceding claims wherein a cross-web (39) is formed outside the chamber across the end having the chamber opening (25) communicating with the tubular duct (30). A container according to any one of the preceding claims wherein the inlet and outlet openings have complementary connection portions (32,48) which are respectively different and are for engagement by complementary connection portions (50,60) from conduits for bringing solvent to and solution from the container, the complementary connection portions (50,60) from the conduits being connectable together to short-circuit the container. A container according to any one of the preceding claims wherein the chamber (2,21) and its inlet and outlet connections (14,32,5,28) and the duct (6,31) are integrally formed together of high density polyethylene. A container according to any one of the preceding claims wherein at least one of the inlet and outlet openings of the container has a neck (28,16) which is plugged by a non-removable collar (40), the collar providing a restricted through-passage (49). A container according to claim 10 wherein the collar (40) is permanently sealed to the neck. A container according to claim 10 or claim 11 wherein the collar (40) includes a filter.

Inventors: FRIZZELL MICHAEL STEWART, FRIZZELL, MICHAEL STEWART
Applicants: RENACARE LIMITED
Application year: 1991
Main classification: B65D1
IPC codes: B65D1, A61J1, B65D85