DE8701394U1 - Connector, especially for medical transfer devices - Google Patents

Description

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VONKKEISLER SCH ON WALD EISHOLD FUEiS VON KREISLER KELLER SELTING WERNER

PATENT ATTORNEYS
Dr.-Ing. von Kreisler 11973

Applicant: Dr.-Ing. KW Efchold 11981

B. Braun Melsungen AG Dr.-Ing. K. Schönwald

Dr. J.F. Fues

DipL-Chem. Alek von Kreisler

&eegr; c &eegr;&eegr; mt &tgr; ,, -r~„ Dipl.-Chem. Carola Keller

3503 Melsungen Dining. G. Selling

Dr. H.-K. Werner

DHCHMANNHAUS AM HABFLBAHNHOF

D-5000 COLOGNE 1

January 28, 1987
Sg-DB/my

connector,
especially for medical transfer devices

The invention relates to connectors made of crystal-clear plastic with a sleeve-shaped hose attachment for inserting or attaching a hose made of crystal-clear plastic to be connected to the hose attachment by means of an adhesive/solvent, in particular for medical transfer devices.

Up to now, crystal-clear PVC hose has been connected to the crystal-clear hose attachment of a connector using an adhesive/solvent (e.g. THF). Both parts are smooth and crystal-clear before and after the adhesive/solvent is applied. Consequently, it is not possible to visually determine whether the parts that have been put together have been wetted with adhesive/solvent or evenly wetted and whether the connection is tight and firm.

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Leaks caused by the complete or partial absence of adhesive/solvent in the area of the hose connection can currently only be detected with extremely high test pressures (>4 bar), as the adhesion between the smooth surfaces of the hose connection and the hose is very strong and does not give way at low test pressures. However, the high test pressures are not necessary because they can damage individual parts of the pipe system, making the test object unusable for the application. For example, the hose can be inflated, the injection options can be destroyed or intact adhesive points can be damaged. Furthermore, high test pressures do not even allow an accurate statement to be made about the tightness of the connection, because after a certain storage time, the defective connection points, which are initially tight without adhesive/solvent, become leaky due to relaxation of the hose even at low working pressures or come loose during storage. The high-pressure leak tests that have been used up to now are not only complex and costly, but also unreliable and harmful to the product. The automation of such pressure leak tests is only possible with great technical effort, which is not worthwhile given the inadequate results.

The invention is based on the object of designing connecting pieces of the type mentioned at the beginning in such a way that the quality of the connection between the hose attachment and the hose can be checked by non-destructive optical inspection.

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This object is achieved according to the invention in that the hose attachment is matted on the surface facing the hose.

On the matte surfaces of the hose connector, the plastic, which otherwise appears crystal clear, takes on a milky appearance and is opaque there. If a hose is now connected to the hose connector without adhesive/solvent, the matte finish does not change and the absence of the adhesive/solvent is clearly visible. On the other hand, if the hose wetted with adhesive/solvent is connected to the hose connector, the dissolving of the plastic material of the hose connector causes the matte surface to become smooth in such a way that the hose connector becomes crystal clear in the places where the adhesive/solvent has created a homogeneous bond. At defective or leaky bonding points, the matte finish of the hose connector surface remains and the defectiveness of the connection is easily visible. From these conditions, conclusions can be drawn about the tightness and strength of the hose-hose connector connection. Defective or leaky bonding points can be identified by a non-destructive test, which can be carried out visually as an in-process control or with the help of technical devices. For example, it is advantageous to run the fully assembled line past a measuring device that uses transmitted light. A 100% check can be carried out inexpensively, thereby achieving a high quality standard. The crystal clarity of the hose attachment and hose achieved when the bonding is correct also shows whether the hose has been correctly connected to the hose attachment.

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This, together with the guaranteed homogeneous bonding, results in high tensile and compressive strength of the connection. No additives are required for the bonding, so there is no risk of a reduction in the bonding quality or of the patient being put at risk through toxicity. Since the assembled line for sealing

' activity control is not subjected to high test pressures? the hose and other individual parts of the line retain their original properties and product safety is very high. If a leak test is to be carried out in addition to the indication of the bonding state achieved by converting it from matt to crystal clear, low test pressures are sufficient for this purpose because possible leaks occur even at low pressures, since only low adhesive forces can act between the matt surface of the hose attachment and the smooth surface of the hose.

In an advantageous embodiment of the invention, it is provided that the matting is formed from a uniform surface roughening. The roughening can be achieved advantageously by not polishing the surfaces of an injection molding tool that form the relevant surfaces of the hose attachment or by slightly structuring them, for example by means of sandblasting or similar processes. Only those surfaces of the connecting piece that are to come into contact with the adhesive/solvent later during bonding should be roughened. This ensures that if the hose is correctly seated and the adhesive bond is homogeneous, the end product is crystal clear overall. In the case of a connecting piece with concentric inner and outer hose attachments that form the

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If the hose end is to be held in an annular gap between them and both are to be glued to it, the inner surface of the outer hose attachment and the outer surface of the inner hose attachment are roughened. When the hose end wetted with adhesive/solvent is pushed into the annular gap between the two hose attachments, the inner surface of one hose end and the outer surface of the other hose attachment are dissolved and the matting effect disappears. The two hose attachments become completely or partially crystal clear and clearly show the nature of the connection between the parts*

The drawing shows embodiments of the invention schematically.

Fig. 1 a top view of a connector for two hoses of different diameters before connection,

Fig. 2 a cross section along line 2-2 in Figure 1,

Fig. 3 is a longitudinal section through the assembled arrangement according to Figure 1 before bonding,

Fig. 4 is a plan view of the arrangement according to Figure 3 after bonding without any defects,

Fig. 5 is a plan view of the arrangement according to Figure 3 after bonding with flaws,

Fig. 6 a partially cutaway plan view of a connector for three identical hoses -and

Fig. 7 is a top view of a drip chamber of a transfusion device with a transfer tube attached.

A connector 10 is made of crystal-clear, rigid plastic and is used for the coaxial connection of a hose 12 with a larger diameter and a hose 13 with a smaller diameter. The two hoses 12 and 13 are made of crystal-clear PVC plastic material and have a certain degree of flexibility. The connector 10 has a central base plate 14 from which hose attachments extend on both sides. In the example according to Fig. 1 to 5, it is provided that the ends of the two hoses 12 and 13 are each accommodated between an inner hose attachment 15 or 17 and an outer hose attachment 16 or 18. The corresponding annular spaces 19 and 20 between the hose attachments 15, 16 and 17, 18 are dimensioned in the radial direction so that they essentially fit the ends of the hoses 12 and 13 so that the surfaces of these parts facing each other touch each other. All hose attachments 15 to 18 are attached coaxially to each other on the base plate 14. A central channel 22 extends through the two inner hose attachments 15 and 17. It is cylindrical in the inner hose attachment 17 and widens conically through the base plate 14 towards the end of the inner hose attachment 15. This design of the channel 22 is advantageous for flow-related reasons.

The cylindrical inner surfaces 16a and 18a of the outer hose attachments 16 and 18 as well as the cylindrical outer surfaces 15a and 17a of the inner hose attachments 15 and 17 are matted * This is indicated in the drawing by a grid or contour zigzag. The matting of the relevant surfaces 153,163,173,183 can advantageously be achieved by positioning the hose connector 10 with an injection molding tool.

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which is evenly structured, for example by sandblasting, at the relevant points so that the injection molding blank has a finely roughened surface. If the ends of the two hoses 12 and 13 are put together with the connector 10 without adhesive/solvent, the even roughening of the surfaces of the hose attachments 15 to 18 remains visible as a matting through the crystal-clear hoses 12, 13 and it is easily visible that the adhesive/solvent is missing and the connection cannot be tight. This undesirable condition is illustrated in Figure 3.

If the inner and outer surfaces of the ends of the two hoses 12 and 13 are properly wetted with adhesive and pushed against the two surfaces of the base plate 14 between the inner and outer hose attachments 15, 17 and 16, 18, the plastic material of the hose attachments 15 to 18 is dissolved by the adhesive/solvent and the roughened surfaces 15a to 18a are smoothed. The smoothing results in the connecting piece 10 becoming crystal clear wherever there is adhesive/solvent. If all surfaces of the connecting piece 10 and hoses 12 and 13 that come into contact with each other are evenly wetted, the arrangement has a flawless, crystal clear appearance - as shown in Figure 4.

Defective adhesive joints, which lead to leaks and reduced tensile strength of the connection, can be visually identified by the fact that frosted areas 21 remain in the otherwise crystal-clear arrangement. This

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is shown in Figure 5, which shows a rejected part. An in-process control can be carried out visually or with the help of a measuring device that works with transmitted light. Since high test pressures are not used to determine the tightness of the connection, product safety is high. ;7if, in addition to the visual control, a leak test is carried out under pressure conditions, the leaks at points 21 become apparent even at low pressures, since only low adhesive forces are effective between the roughened points 21 of the hose attachments 15 to 18 and the smooth surfaces of the hoses 12 and 13. Damage to the product due to test pressures is therefore excluded and a high quality standard is guaranteed.

The principle of surface roughening as a means of making bonding defects visible can be applied to all crystal-clear products with a hose attachment. Further examples are shown in Figures 6 and 7.

In the example according to Figure 6, three hoses 30, 31, 32 are connected to one another via a connecting piece 35. The connecting piece 35 is a flat body made of plastic, which has a hose attachment 36 directed to one side and two hose attachments 37, 38 directed to the other side and parallel to one another. The three hose attachments 36, 37, 38 are connected to one another via an opening 39, so that the lumens of the three hoses 30, 31, 32 are connected in terms of flow. The inner surfaces of the hose attachments 36, 37, 38 are matte, as indicated by the grid. If the hoses 30, 31, 32 are correctly inserted and the adhesive/solvent (e.g. THP) is evenly distributed, a uniform dissolution of the matte

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ated surfaces and a full-surface bonding of the parts, the connecting piece 35 is crystal clear overall and a measuring device using transmitted light determines that the fully assembled coupling for the connection of several infusion or transfusion lines is 100% tight. The homogeneous bonding ensures high pressure and tensile strength of the connection.

In the example according to Figure 7, the lower end of a drip chamber 'Ø of a transfusion device is firmly connected to a transfer tube 41. The drip chamber

[v 40 consists, including its piercing mandrel 42, of

crystal-clear plastic and at their lower end there are also crystal-clear hose attachments 43,44, with which the inner and outer surfaces of the end of the transfer hose 41 are glued. In this case too, it is advantageous to make the inner surface of the outer hose attachment 43 and the outer surface of the inner hose attachment 44 matt, e.g. using an appropriately roughened injection mold, in order to enable visual control of the tightness and strength of the bond, in order to be able to determine the quality of the bond by observing any milky spots that may remain after the bonding.

The bond is homogeneous and tight when the hose connections 43,44 are flawlessly crystal clear.

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Claims (2)

- 10 CLAIMS 1. Connector made of crystal-clear plastic with a sleeve-shaped hose attachment for inserting or attaching a hose made of crystal-clear plastic to be connected to the hose attachment by means of an adhesive/solvent, in particular for medical transfer devices,
characterized in that the hose attachment (15-18) is matt on the surface (15a-18a) facing the hose (12,13). 2. Connecting piece according to claim 1, characterized in that the matting is formed from a uniform surface roughening. I« ti 44 ·· &Lgr; Hit Il I ti * I * · # «III t * ie* i it**