IE53948B1

IE53948B1 - Hollow-fibre apparatus

Info

Publication number: IE53948B1
Application number: IE703/83A
Authority: IE
Original assignee: Hospal Ind
Priority date: 1982-04-27
Filing date: 1983-03-29
Publication date: 1989-04-26
Also published as: EP0093677A1; FR2525487B1; EP0093677B1; IE830703L; JPS5911866A; DE3365074D1; FR2525487A1

Abstract

1. An apparatus, for the treatment of blood in particular, comprising inside an elongate envelope (10) provided with inlet openings (11, 13) and outlet openings (12, 14) for the blood and for an auxiliary fluid respectively, at least one bundle (16) of substantially rectilinear, selectively permeable hollow fibres, open at their ends, sealed in a leakproof manner towards each one of their ends in zones delimiting inside the said envelope, a central compartment (20) traversed outside the hollow fibres by the said auxiliary liquid and two lateral compartments (21, 22) interconnected by the hollow fibres internally traversed by the blood, the said bundles being solely constituted by hollow fibres intersecting each other within a web rolled up into a spiral on itself around a longitudinal axis, characterised in that the said hollow fibres are intersected according to angles alpha comprised in the open range of 1 degree-5 degrees in relation to the said longitudinal axis.

Description

The present invention relates to a hollowfibre fluid treatment apparatus, especially for treating blood, and also to a bundle of hollow fibres which can be used in this apparatus, a method of manufacturing such a bundle of hollow fibres, and equipment which makes it possible to carry out this process. The hollow fibres are here only a particular form of membrane permitting exchanges between two fluids, one of which is, in particular, blood. Apparatuses of this type are generally used as haemodialysers or blood oxygenators,but also as ultrafilters, haemofilters or plasmapheresis apparatus.

For greater convenience, reference will be made hereafter essentially to a haemodialyser.

Numerous haemodialysers are already known which consist essentially of a bundle of hollow fibres through which the blood flows on the inside. A considerable problem is to obtain effective exchanges between the blood and the dialysis liquid. This requires, in. particular, an active and uniformly distributed flow of the dialysis liquid around the hollow fibres.

Leaving the distribution of the hollow fibres to chance generally leads to preferential passages for the 3 9 4 8 dialysis liquid and to a generally unacceptable drop in efficacy. Hollow fibres were therefore assembled substantially parallel to give mats, which were then rolled up, but this involves a series of difficult operations and heavy investment.

It is now proposed, according to the invention, to form a web of hollow fibres which interact with one another at relatively small angles to a longitudinal direction, and then to roll the web up into a spiral about on axis parallel to the said longitudinal direction.

Such a structure can be made generally satisfactory. However if the angle is too small this causes the fibres to roll up non-uniformly so that they tend to become parallel and this tends to give an isotropic laminated structure, in particular with respect to the location of the inlet and outlet orifices for dialysis liquid, which is not entirely satisfactory.

On the other hand, if the angle is too large, this requires soft hollow fibres virtually devoid of elasticity so that they can be rolled up in a spiral in this way without separating.

Thus according to the present invention there is provided a fluid treatment apparatus, especially suitable for treating blood, said apparatus comprising an elongate envelope having an axis extending between the two ends thereof, a first inlet and a first outlet 3 δ 4 8 for a first fluid, one adjacent each end of said envelope, a web of selectively permeable substantially rectilinear hollow fibres, the hollow fibres being arranged in lines which intersect one another at angles to a longitudinal direction of between about 1° and 5°, the web being wound up into a spiral bundle having an axis parallel to said longitudinal direction, the spiral bundle being located in said envelope, with its axis extending axially of the envelope, means sealing the hollow fibres to one another and to the envelope adjacent the two ends of the hollow fibres, thereby to define a central compartment between said sealing means and an inlet compartment communicating with said first inlet and an outlet compartment communicating with said first outlet, a second inlet and a second outlet communicating with said central compartment and open ends to said hollow fibres communicating with said inlet compartment and said outlet compartment respectively.

Such a construction does not have the disadvantages observed hitherto, and can use hollow fibres having moderate mechanical characteristics, in particular as regards the elasticity· It is capable of improved efficacy, both from the point of view of the level of the performance characteristics and from the point of view of the uniformity of the performance characteristics obtained. 3 & <2 S Furthermore the apparatus can be made by a process which is simple, reliable and economic· The present invention also relates to the structure of the bundle of hollow fibres with which this apparatus is equipped, and also to a process for the manufacture of this bundle and to the equipment which makes it possible to carry out this process.

The invention will be more fully understood from the following description, which is given merely by way of example, reference being made to the accompanying drawings, in which:Figure 1 is a diagrammatic side elevation, partly in section, of one embodiment of a haemodialyser according to the invention; Figure 2 is a diagrammatic view of part of one form of equipment used to manufacture bundles of hollow fibres according to the present invention; Figure 3 is a plan view of a support plate on which the successive layers of intersecting hollow fibres, twisted together, are arranged, according to a particular embodiment of the present invention; Figure 4 is a diagrammatic view, in section, taken along the line IV. IV of Figure 3; and Figure 5 is a perspective view of a particular embodiment of the bundle of hollow fibres according to the invention, while it is being made into a spiral.

Figure 1 shows a haemodialyser comprising an elongate envelope 10 provided with orifices 11 and 12 for the introduction and discharge, respectively, of the blood and orifices 13 and 14 for the introduction and discharge of the dialysis liguid. This elongate envelope consists of a cylindrical shell 15 made of a thermoplastic, for example polycarbonate, at the ends of which two ferrules 16 and 17 are ultrasonically welded. A bundle 26 of hollow fibres, constituting an advantageous form of semi-permeable membranes of any known type used in haemodialysis and haemofiltration, rests inside the envelope 10.

These hollow fibres have substantially rectilinear general directions, nevertheless allowing a few undulations, are open at their ends and are sealed near their ends, to one another and to the walls of the shell 15, with a polymerisable resin 18 such as an epoxy and/or polyurethane compound. The apparatus is thus divided into a central compartment 20 through which the dialysis liquid flows, on the outside of the hollow fibres, and into two compartments 21 and 22 connected to one another by hollow fibres through the interior of which the blood flows.

The seal is completed by O-rings such as 19. These general arrangements are in themselves well known and will not therefore be described in greater detail here. The present invention in fact relates essentially to the particular arrangements of the hollow fibres inside S3&48 the bundle 26.

It has in fact been found that it is possible virtually to eliminate any preferential passage for dialysis liquid outside the hollow fibres and to obtain an active and uniformly distributed flow of the dialysis liquid around the hollow fibres, over the major part of their outer surface, if a bundle of hollow fibres intersecting to a small extent is formed, without a preferential direction, that is to say inside a web of hollow fibres which is rolled up into a spiral parallel to the longitudinal axis of the apparatus. In practice, the hollow fibres intersect at angles a which are generally between 1° and 5° relative to the longitudinal axis of the bundle.

If the hollow fibres are inclined at an angle a of less than 1°, it is found that they do not form a homogeneous layer capable of being rolled up uniformly into a spiral, but that, on the contrary, they tend to become placed non-uniformly, parallel to one another.

If,conversely, the hollow fibres form an angle a of more than 5°, it is found that they are very unsuitable for being rolled up into a spiral; in particular, they tend to separate from the web, especially at the edges.

Acccording to a particular characteristic of the present invention, it is possible to form bundles 26 of hollow fibres either from a single hollow fibre or from an elementary bundle of several hollow fibres treated simultaneously. In fact, it is advantageous, for reasons of productivity, to produce simultaneously and/or to assemble n identical hollow fibres, n generally being between 2 and 40 and preferably between 4 and 20. These n hollow fibres can come from a feed spool, which is either supplied directly from an installation for the simultaneous manufacture of a plurality of hollow fibres, or originates from a storage zone.

Each elementary bundle consists of a plurality of hollow fibres, which can be either contiguous but independent of one another, or connected to one another.

In the latter case, the hollow fibres can be braided or twisted together, with or without torsion on the fibres. The means described in U. S. Patents Nos. 3,963,622 and 4,236,120 Coin advantageously be used for this purpose. According to the present invention, each elementary bundle 23, once formed, is treated like a single hollow fibre.

In particular, the elementary bundles 23 are made to intersect at angles a which are generally between 1 and 5° relative to the longitudinal axis of the bundle 26.

The hollow fibres or the elementary bundles 23 of hollow fibres are crossed when they form a web 40 (Figure 3) of hollow fibres, located substantially in a plane. Rolling up this web into spirals at 24 gives the hollow fibres, initially intersecting at a small angle in a plane, inclinations which always remain between 1 and 5° relative to the axis of the bundle 26. Furthermore, 53&4S these hollow fibres or elementary bundles 23 of hollow fibres no longer remain orientated in various directions within the initial plane or in parallel planes, but are orientated in any plane tangential to the spiral described by the web 40.

This results in new structures of bundles of hollow fibres. The body of hollow fibres obtained is substantially a body of revolution and relatively anisotropic, especially with respect to the location of the inlet and outlet orifices for the dialysis liquid, all the more so because a relative interpenetration of the hollow fibres (or of the elementary bundles 23)is generally observed from one spiral layer into an adjacent layer. Any preferential passage is thus prevented inside the bundle 26.

Any preferential passage within the bundle 26, on the one hand, and between the latter and the container 15, on the other hand, is also prevented if the bundle 26 is given a sufficient compactness.

This compactness can be expressed as the ratio of the sum of the cross-sections of all the hollow fibres in the bundle, (calculated on the basis of their external diameter) to the cross-section available inside the container 15. This ratio is generally between 0.4 and 0.9 and preferably between 0.6 and 0.7.

To achieve this result, it is most frequently necessary to compress the bundle 26 of hollow fibres laterally before introducing it into the container 15.

In the absence of lateral stresses, the bundle of hollow fibres according to the invention in fact has an average diameter which is greater than the internal diameter of the container intended for accommodating it. The bundle according to the invention must therefore be able to be compressed without the fibres being crushed.

It is therefore generally elastic. The ratio of the average diameter of the bundle, in the absence of lateral stresses, to the internal diameter of the container shell intended for accommodating it is generally between 1 and 1.5 and preferably between 1.1 and 1.3.

Advantageously a cylindrical bundle of hollow fibres with a circular base and homogeneous compactness is formed (see Figure 5). To do this, the thickness of the web of hollow fibres is gradually tapered, over a distance d, at its outer end when it is rolled up into a spiral, so that the assembly formed by the spiral web naturally inscribes itself inside a circle, without it being necessary locally to modify its compactness or to disturb the arrangement of the intersecting hollow fibres.

The semi-permeable hollow fibres making it possible to carry out the present invention can be of various known types used in blood treatments, especially by haemodialysis and haemofiltration. Hollow fibres ί> 3 ί/ 'ί i made of acrylonitrile copolymers are particularly suitable. These hollow fibres have an external diameter which is generally between 50 and 2,000 microns and preferably between 100 and 500 microns. The wall thickness is generally between 5 and 200 microns and preferably between 10 and 80 microns. Advantageously, the hollow fibres which can be used according to the present invention are relatively flexible, supple and elastic, so that they can bear on one another and bend slightly without becoming blocked.

The modulus of elasticity of hollow fibres which can be used according to the invention is advantageously between 100 and 500 megapascals. By way of example, the modulus of elasticity of a hollow fibre made of acrylonitrile copolymers, which is preferably used for the manufacture of an apparatus according to the invention, is 220 megapascals.

At least on the surface, various types of hollow fibres are in the moist and/or plasticised state, for example impregnated with water and/or glycerol, in particular to preserve their permeability properties and also their mechanical characteristics. It has been observed that these hollow fibres have a cohesion which facilitates the formation of spiral webs.

In one particular construction, two series of bundles each, comprising, in each unit, 6,000 fibres ε 3 δ ύ ε having a total active surface area of 1.14 m and external and internal diameters of 390 and 290 microns respectively, are thus formed using these hollow fibres. Each bundle is introduced into a conventional container for forming a haemodialyser. These two series of haemodialysers differ only in the structure of the bundle. In the first series, the control haemodialysers consist, in a known manner, of a bundle of substantially parallel fibres. In the second series, the haemodialysers consist of identical hollow fibres, but they intersect and are rolled up into spirals according to the invention.

Under identical conditions (in vitro experiments: blood flow rate: 200 ml/minute, dialysis liquid flow rate: 500 ml/minute), the average urea purification level (Clearance) observed is: - 170.7 for the haemodialysers according to the invention, compared with: - 153.3 for the control haemodialysers, that is to say an improvement of the order of 10%.

However, it is noted, in particular, that the standard deviation in performance from one haemodialyser to another, for a probability factor of 95%, is reduced from 14.5 (control haemodialysers) to 3.2 (haemodialysers according to the invention). Thus, a noteworthy improvement in the uniformity of performance, and hence in the reliability of this type of apparatus, is observed.

To manufacture a bundle of hollow fibres such as described above, the procedure according to the invention is as follows, reference being made especially to Figure 2.

A hollow fibre 33 is unwound from a spool 30, for example a fixed spool, with the aid of a rotary winder 31 optionally driven at constant speed by a geared motor set 32, and the hollow fibre is wound around the lateral surface of a drum 34, which is caused to rotate at constant speed by a speed-reducing geared motor 35 and conventional transmission means such as pulleys and a belt 36, about an axis substantially perpendicular to the mean position of the hollow fibre 33 between the feed spool 30 and the drum 34.

In fact, this hollow fibre 33 is directed onto the drum and guided laterally, alternately from one end to the other of this drum, at constant transverse speed, with the aid of a traversing device 33 actuated by a geared motor 38. The speed of the geared motor 38 relative to that of the geared motor 35 is adjusted so that, when being laid on the drum 34, the hollow fibre 33 forms a substantially constant angle a, which is generally between 1° and 5°, with a plane perpendicular to the axis of the drum.

Thus, a first layer of hollow fibres is formed on the drum 34 by guiding the hollow fibre from left to right. 3 9'. ϊ· for example, and a second layer, which is placed over the previous layer, is then formed by guiding it from right to left. The hollow fibres of these two layers therefore intersect uniformly and symmetrically relative to a plane perpendicular to the axis of the drum. The desired number of successive layers of hollow fibres are laid on the drum 34 in this way.

The movement of the drum is then stopped and the hollow fibres arranged on the drum are then cut, with the aid of the knife 39, along the planes parallel to the axis of the drum and at regular intervals substantially corresponding to the desired length of the bundles of hollow fibres. This gives a series of webs 40 of hollow fibres, such as that shown in Figure 3.

Each web is thus made up by the superposition of several layers 41 of intersecting hollow fibres, shown diagrammatically in section in Figure 4. Each web 40 has a substantially plane and rectangular general shape.

It comprises the envisaged amount of hollow fibres forming each bundle. For example, a bundle of hollow 2 fibres having a useful surface area S of 1 m can be formed from a web of 5,000 hollow fibres having an individual external diameter of 400 microns and a length of 23 cm, arranged in successive layers each extending over the same length of 55 cm.

It may be convenient for the hollow fibres in forming each web to be held in place on its support, at least temporarily, for example by using adhesive or non-adhesive elastic strips, such as 42 and 43, fixed to the web support, for example at their ends, and immobilizing the hollow fibres along their open ends.

It is then possible to roll up the web of hollow fibres into a spiral, so that the bundle fonned in this way is composed of hollow fibres open at both ends. This is carried out using any known means, either manual or mechanical. Advantageously, the hollow fibres are fixed to the edges beforehand by glueing, sewing, guiding or any equivalent means.

It is advantageous if the generally moist hollow fibres adhere only very slightly to their support 44, which consists, for example, of a metal plate.

Satisfactory results can be achieved using a variety of means such as perforated plates, latticed plates or plates covered with a plastic mesh 45 fixed to the support plate 44, in order to prevent the formation of a liquid film and to reduce the capillary forces.

The web of hollow fibres is thus entirely rolled up into a spiral and forms a bundle of substantially cylindrical shape. This is then compressed laterally so that it can be introduced into the container 15 forming part of the apparatus with which it is to be used.

Advantageously, a thermoplastic film is wound around the bundle, the whole is introduced into the container and the thermoplastic film is then removed, if appropriate, which makes it possible to handle the bundle easily without damaging the hollow fibres.

The process according to the invention, which has been described in the case of a single hollow fibre, can advantageously be used under analogous conditions starting from a plurality of hollow fibres, these originating either from the same spool 30 or from several similar spools arranged in parallel. As seen above, by combining several hollow fibres in this way, in parallel, it is possible to form an elementary bundle generally comprising from 2 to 40 hollow fibres and preferably from 4 to 20 hollow fibres. Advantageously, the hollow fibres of which an elementary bundle is composed can be twisted together before the bundle is wound on the drum 34.

According to a preferred embodiment of the process according to the invention, the thickness of the web of hollow fibres is progressively tapered, over a distance d, at the outer end when it is rolled up, so as to give a cylindrical bundle of hollow fibres of homogeneous compactness.

To do this, means are used for gradually reducing, on one side, the extent of the lateral movement of the traversing device. Means which can be used are for example, a cam 46 driven by a geared motor set 47, s & i. ε which revolves once about itself, at constant speed, during the complete loading of the drum 34 with hollow fibres.

The profile of the cam 46 is determined in such a way that it gradually limits, on only one side, the lateral stroke of the traversing device 37 which guides the hollow fibre 33 or the corresponding elementary bundle. Periodically, the traversing device 37 thus butts against the cam 46 and then immediately starts again, in the opposite direction, at the same speed. Figure 4 shows that this gives several layers (4la, 4lb, 4lc, 4ld) of hollow fibres, which, towards one end of the support plate 44, are offset relative to one another over the zone (d). The profile of the cam makes it possible to adjust the number of layers of hollow fibres in question and the depth of the maximum offset necessary for obtaining a cylindrical bundle of homogeneous compactness.

The means used according to the present invention are essentially as follows: a) Means for feeding a single hollow fibre or a plurality of hollow fibres, these means comprising spools supplied directly or indirectly from at least one installation for the manufacture of single or multiple hollow fibres, generally from 2 to 40 hollow fibres and preferably from 4 to 20 hollow fibres. A device comprising mechanised winders can facilitate the take-up of the hollow fibre or fibres. If appropriate, it is possible to use a device of a type which is in itself known for braiding or twisting the hollow fibres. b) A drum 34 with means for causing rotation at constant speed 35, 36. This drum can have a circular base, especially in the case of a large diameter, but it preferably has a regular polygonal base of p sides, p generally being between 3 and 30 and corresponding to the number of bundles 26 of hollow fibres which can be manufactured simultaneously from the same drum. In practice, the drum 34 generally comprises, at each end, a polygonal face 48 of p equal sides (p = 6 sides in Figure 2), which is fixed to the rotation shaft of the drum. A preferably plane support plate, 44, rests on each of the sides of the faces and is fixed to each face by means of bolts 49. These support plates 44 can be either independent of one another or articulated to one another in order to make them easier to handle. Advantageously, the support plates 44 comprise means which substantially reduce the adhesion of the hollow fibres when they come into contact: for example, they are perforated, goffered or covered with a mesh of plastic filaments 45. c) A traversing device 37 for laterally guiding the hollow fibre 33 or the corresponding elementary bundle C> <5 & U of hollow fibres onto the drum 34. This device is actuated with an alternating movement of constant speed, of a type which is in itself known, comprising especially a geared motor set 38. The ratio of the drive speed of the traversing device to that of the drum is such that the hollow fibres wind onto the drum, forming an angle a of between 1° and 5° relative to a plane perpendicular to the axis of the drum.

Preferably, as seen above, a cam device 46 can limit the lateral movement of the traversing device on one side, in accordance with a predetermined program. d, Means for cutting the hollow fibres on the drum. These means consist, for example, of a microtome blade capable of moving parallel to the axis of the drum 34 to cut the hollow fibres parallel to this axis over the whole length of the drum. Preferably, cutting takes place between two support plates 44, in the region of each of the p vertices of a face 48. e) Means 42, 43 for at least temporarily holding the hollow fibres, or elementary bundles of hollow fibres, towards their ends, on the supports 44 before they are made into a spiral. These means can consist, for example, of strips, preferably elastic strips, passed over the hollow fibres and around the support plates 44. f) Means of types which are in themselves known, either mechanical or manual, for rolling up the webs of hollow fibres into a spiral and thus forming bundles, of homogeneous compactness, of hollow fibres open at both ends.

Numerous modified embodiments will he apparent to those skilled in the art within the scope of the present invention. For example, the apparatus according to the invention can comprise several bundles similar to 26, juxtaposed side-by-side in the same container casing. The present invention permits simple, reliable and economic manufacture of apparatuses giving excellent performances with a high degree of uniformity. Other than as haemodialysers and/or blood ultrafilters, these apparatuses are advantageously used for treating blood, especially as oxygenators, haemofilters or plasmapheresis apparatuses.

Claims

1. A fluid treatment apparatus, especially suitable for treating blood, said apparatus eomprisings an elongate envelope having an axis extending between 5 the two ends thereof, a first inlet and a first outlet for a first fluid, one adjacent each end of said envelope, a web of selectively permeable substantially rectilinear hollow fibres, the hollow fibres being arranged in lines which intersect one another at angles 10 to a longitudinal direction of between about 1° and 5®, the web being wound up into a spiral bundle having an axis parallel to said longitudinal direction, the spiral bundle being located in said envelope, with its axis extending axially of the envelope, means sealing the 15 hollow fibres to one another and to the envelope adjacent the two ends of the hollow fibres, thereby to define a central compartment between said sealing means and an inlet compartment communicating with said first inlet and an outlet compartment communicating with said first 20 outlet, a second inlet and a second outlet communicating with said central compartment and open ends to said hollow fibres communicating with said inlet compartment and said outlet compartment respectively.

2. Apparatus as claimed in claim 1, wherein 25 said web of hollow fibres comprises a plurality of 5 3 il elementary bundles each consisting of between 2 and 40 hollow fibres.

3. Apparatus as claimed in claim 2, wherein said elementary bundles consist of hollow 5 fibres which are twisted together.

4. Apparatus as claimed in claim 1, 2 or 3, wherein said web comprises several layers of superposed hollow fibres of uniformly decreasing length towards one end of the web, whereby, when said 10 web is wound up into a spiral it has a cylindrical outer surface of homogeneous compactness and with a circular base.

5. Apparatus as claimed in any preceding claim, wherein said hollow fibres are made of 15 acrylonitrile copolymers.

6. Apparatus as claimed in any preceding claim, wherein said hollow fibres have a modulus of elasticity between 100 and 500 megapascals.

7. Apparatus as claimed in any preceding 20 claim, wherein said hollow fibres are moist and/or plasticised.

8. A web of selectively permeable substantially rectilinear hollow fibres, the hollow fibres being arranged in lines which intersect one 25 another at angles to a longitudinal direction of between about 1° and 5°, the web being wound up into a spiral bundle having an axis parallel to said longitudinal direction and intended for use in apparatus according to any one of claims 1 to 7.

9. A method for the manufacturing of a bundle 5 of hollow fibres which can be used in a fluid treatment apparatus according to any one of claims 1 to 7, said method including the steps of:a) winding at least one hollow fibre from at least one spool onto a drum, alternately towards

10. Each end of said drum, whereby said hollow fibres form successive layers, the fibres of one layer intersecting those of the next layer to form angles of between 1° and 5° with a plane perpendicular to the axis of said drum? 15 b) cutting the hollow fibres along planes parallel to the axis of the drum, at regular intervals substantially corresponding to the desired length of the bundles, to form a plurality of webs of substantially plane, intersecting hollow fibres, open at both ends; 20 and c) winding up said webs of intersecting hollow fibres into a spiral to form bundles of intersecting hollow fibres open at both ends of the bundle. 25 10. A method as claimed in claim 9, and further comprising forming beforehand an elementary bundle of between 2 and 40 hollow fibres to thereafter be treated as one hollow fibre. 3 iJ 4 L Sil

11. The method as claimed in claim 10, and further comprising the step Of twisting said hollow fibres together before the elementary bundles are wound onto said drum. 5

12. A method as claimed in claim 9, 10 or 11, wherein the thickness of the web at one end is gradually reduced.

13. Equipment for implementing a method according to any one of claims 9 to 12, said equipment 10 comprising, in combination:a) means for feeding at least one hollow fibre; b) a cylindrical drum and means for driving said drum at a constant speed of rotation;

14. 15 c) a constant-speed traversing device for guiding said at least one hollow fibre laterally from said feed means onto said drum, the ratio of the drive speed of the traversing device to that of said drum being such that the hollow fibres wind onto said drum, 20 forming an angle of between 1° and 5° relative to a plane perpendicular to the axis of said drum; d) means for cutting the said hollow fibres along a plane parallel to the axis of said drum, at regular intervals; 25 e) means for at least temporarily holding the cut ends of the hollow fibres on their supports; and f) means for winding up the said webs of hollow fibres into a spiral forming a bundle of homogeneous compactness of hollow fibres open at both ends. 5 14. Equipment as claimed in claim 13, wherein said drum comprises a base consisting of polygonal faces with p sides, a plane support plate of hollow fibres connecting each of the several sides of the two faces, clamping means holding said support 10 plates on said end faces.

15. Equipment as claimed in claim 14 further comprising means which substantially reduces adhesion of the hollow fibres at their contact surface on said support plates. 15

16. Equipment as claimed in claim 13 and further comprising means for gradually reducing the extent of movement of said traversing device at one end of its traversing motion.

17. A fluid treatment apparatus according 20 to claim 1, substantially as hereinbefore described with particular reference to and as illustrated in Fig. 1 and Figs. 3-5 of.the accompanying drawings.

18. A method according to claim 9, substantially as hereinbefore described with particular refer25 ence to and as illustrated in Fig. 2 of the accompanying drawings. < ε

19. Equipment according to claim 13, substantially as hereinbefore described with particular reference to and as illustrated in Fig, 2 of the accompanying drawings.