Liquid degassing device

The invention relates to a device for removing gases from liquids, in particular a dialysis liquid.

In the construction of an extracorporeal blood circuit as well as in the preparation of dialysis fluids for dialysis a plurality of means for the separation of air in the form of bubble traps or air extraction means is known, which have the task of the present in the liquid, some of the dissolved gases from the liquid effectively to separate.

The coming in dialysis for use dialysis fluid set free under reduced pressure gases, air separators are used, which have an upper inlet, which is usually arranged laterally and the incoming fluid is to impart a spiral path. The air bubbles are to be deposited by an overhead hydrophobic filter. Such an arrangement is known for example from DE 32 15 003. In practice, however, was determined that the separated air is entrained in part to the outlet by the resulting suction, so that further measures had to be taken to improve the deposition. For example, separating aids were introduced in the form of small plates in the discharge chamber. Furthermore, the air separator were often built very long to make the deposition surface as large as possible.

From US-A-4,061,031 discloses a device which can be used both as a flow meter as well as air separators use. The known device comprises a container which is divided by a partition into two chambers, of which the one chamber with the inlet port and the other chamber is provided with the outlet opening. The partition wall has an opening and extending from the bottom of the container to close the container ceiling, forming a gap-shaped space between the inlet chamber and the outlet chamber and the container ceiling.

The perforated partition is offset by two mutually arranged, formed plate-like elements, wherein the openings of the inlet and outlet chambers are located at the bottom of the container. Since the aperture has a smaller cross-section than the inlet port, are formed in the chambers of the liquid columns of different heights, whereby it is possible to measure the flow. The difference between the two Flüßigkeitsäulen is a measure of the amount of flow.

In the known device both chambers serve as a bubble trap. The present in the liquid bubbles rise in the chambers upwards and remain as a gas above the liquid level. An active deposition is not possible with the known device. So that the liquid does not flow over the upper edge of the partition wall into the outlet chamber, the inlet chamber has an elongated shape, which leads to a relatively large overall height.

The invention is based on the object to provide a device for removing gases from liquids, with which can achieve a high deposition rate with compact design and simple construction.

The problem is solved according to the invention having the features of claim 1.

In the apparatus according to the invention, the partition wall is formed as a continuous body such that the first opening and the second opening is restricted on the gaplike space in flow communication. Further, a vent is provided on the container cover, which is closed by a ventilation unit that transmits Although gas but no liquid. During operation, the container, ie the two chambers and the gap-shaped intermediate space, completely filled with liquid. The liquid to be degassed flows from the one chamber via the gap-shaped intermediate space below the container ceiling in the other chamber. On the partition wall a reverse the direction of flow takes place, with the gases contained in the liquid can exit through the container provided on the ceiling vent.

A particularly high deposition rate with a compact construction of the device is in particular achieved when the partition is in the form of a hollow body, which is arranged within the container to form the first and second chambers, that the inner first chamber a lower Querschitt than the outer having lying second chamber. In this arrangement, the first chamber forms the feed chamber and the second chamber forms the discharge chamber. Since the feed chamber has a smaller cross section than the outlet chamber, the flow rate is increased in the first chamber and hence the static pressure at the vent opening. On the other hand, the dynamic pressure at the vent hole is made small, so that in spite of the increased flow velocity in the first chamber, no air is entrained practical.

The ventilation unit can be formed in the inventive device, for example as a hydrophobic membrane. This is advantageously integrated in the ceiling, so that the liquid to be degassed is pressed against the membrane. The hydrophobic membrane should be used for the liquid form as large a contact surface and preferably extend over almost the entire cross-sectional area of ​​the gap-shaped interspace.

The supply opening to the first chamber is configured in a preferred embodiment so that the liquid supplied may flow horizontally, this horizontal flow component advantageously has a tangential Stömungskomponente is impressed. This has the consequence that the incoming liquid is conveyed substantially helically upwardly, whereby the separation of air is also enhanced. The incoming fluid mixture is thus set into a rotational movement within the air separator according to the invention, whereby gas is conveyed forcibly in the direction of the common axis.

In a further preferred embodiment, the bottom of the inner tubular portion of the first chamber opposite the bottom of the outer part of the second chamber extended downwardly and extends downwardly accordingly. In this embodiment, the inlet opening is disposed adjacent to the tubular side wall to the bottom, wherein the communicating with the first opening in fluid communication feed connector advantageously opens tangentially to the tube wall in the first opening.

Similarly, the outlet connection from the second opening may be arranged ebentalls horizontally adjacent to the ground and, where appropriate, tangential flow to the container wall in the second opening.

Particularly preferred is the embodiment in which the horizontal walls of the first chamber and the second chamber are formed circular and thus a form tube-in-tube arrangement so that between the first chamber and the second chamber, a circular annular space is formed.

Further advantageous embodiments and advantages are shown in the drawing.

Show it<ul><li>Fig. 1 shows a longitudinal section through a first embodiment of the invention,</li><li>Fig. 2 is a view of the embodiment of Figure 1 from below, and</li><li>Fig. 3 shows a second embodiment of the invention in longitudinal section.</li></ul>

In Fig. 1, 10 a device for removing gases from medical fluids, in particular for removing air from a dialysis fluid shown having a container 12. This container 12 has a substantially vertically arranged container wall 14, which is designed circular in accordance with the embodiment shown in Fig. 1 substantially. The container 12 is bounded on its underside by a container base 16 and on its upper side by a container ceiling 18th

According to the embodiment shown in Fig. 1 of the container base 16 is stepped to form a step 20, whereby the container bottom in an outer annular portion 22 and an inner divided substantially circular region 24 is. Accordingly, the stepped portion 20 forms a substantially cylindrical region 26th

The container 12 has an interior 28 which is divided by an annularly closed wall 30 into a first chamber 32 which is located within the annular wall 30, and a second chamber 34 having a substantially annular structure, the annular wall 30 surrounds and is delimited by the container wall fourteenth

The annular wall 30 is secured on the container bottom 16 and in accordance with the embodiment shown in FIG. 1 is formed so that it passes over the annular bottom portion 22 in the cylindrical region 26 and coincides with this region. On the other hand, but also the whole of the floor 16 may be flat, so that the annular wall 30 is positioned on this bottom and is fastened to this bottom.

In the area of ​​the bottom 16 a first opening 38 is provided in the first chamber 32, which is advantageously used as a supply port. This first port 38 is arranged in accordance with the embodiment shown in FIG. 1, in the downwardly projecting cylindrical portion 26.

The bottom 16 opposite end of the annular wall 30 is guided into the vicinity of the tank lid 18, and opens there into a tube opening 39, which is delimited by a circumferential edge of the tube 40, which represents an overflow weir for a supplied liquid. Between the tube edge 40 and the container ceiling 18 a gap-shaped flow space 42 is provided, which creates a flow connection between the first chamber 32 and second chamber 34 via the tube 40 away edge.

The cross-sectional shape of the container 12 as well as its members 14 and 30 is substantially not critical, but preferably circular, and the two pitch circles of the outer wall 14 and the wall 30 preferably have a common center of circle.

Advantageously, the inner first chamber 32 is designed as a feed chamber, while the concentric outer second chamber 34 serves as a discharge chamber. Here, the discharge chamber advantageously has a larger cross-section than the feed chamber, so that the fluid can flow substantially unimpeded through the pipe edge 40 away. In the whole container prevails no substantial pressure difference.

It should be added, however, that a different flow to the container is possible, for example also a flow from the outside to the inside, although this is not preferred.

According to the embodiment of Figs. 1 and 2, a first pipe socket 44 is arranged at the first chamber 32 in the region of the first tube opening 38. It opens the pipe longitudinal axis of the pipe socket. 44 - as shown in Figure 2 can be seen - advantageously tangentially in the circular shape of the first chamber 32 and passes the rest to the position of use substantially horizontally.

Furthermore, a second pipe connection 46 is arranged at the second chamber 34 in the region of the second opening 36, which serves as outlet connection, wherein the axis of which is advantageously also arranged horizontally in the use position.

The arrows shown to the pipe sockets 44 and 46 in Fig. 1 or 3 show here to the respective inflow and outflow directions.

Furthermore, the vessel top 18 a vent hole 48 which is closed by a venting unit. In the embodiment shown in Fig. 1, the ventilation unit is a microporous hydrophobic filter 50 which, but not the aqueous liquid passes the separated gas. As far as the hydrophobic filter is concerned, reference 32 15 003 made to the disclosure of DE.

Compared to the embodiment shown in FIG. 1, the container is different 52 shown in FIG. 3, in which used for the same parts the same reference numerals as in Fig. 1, only in that the vessel top cone 54 toward the vent hole 48 upwardly tapered, and the vent hole 48 having a charging pressure relief valve 56 as a ventilation unit, which can be connected via a line 58 to a hydraulic unit, not shown.

The containers 12 and 52 are usually made of a plastic material and serve for the separation of air in the production of, for example dialysis fluid as Primärluftabscheider. The physically dissolved in the liquid air is removed from the freshly prepared liquid first in a vacuum path released. The liquid / air mixture is fed to the pipe stub 44, and due to the tangential introduction, the mixture helically moves upward and thus the air in the direction of body axis to form small bubbles is forcibly separated from the liquid.

then the deposition of air in the area of ​​the hydrophobic membrane 50 and of the boost pressure valve 56th

A great advantage of the inventive apparatus for removing gases is the simple continuous and highly efficient separation of air, particularly in the single-pass-dialysis. Another advantage is that the container of the device is constantly filled with liquid, so that in this way a very good disinfectant or Freispülbarkeit is given. Finally, the dimensions of the device according to the invention can be reduced by about half, due to their good release properties compared to the air separators currently used.