GB2254169A

GB2254169A - A flow regulator and a process for its manufacture

Info

Publication number: GB2254169A
Application number: GB9205057A
Authority: GB
Inventors: Lucas Victor Grifols
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-03-18
Filing date: 1992-03-09
Publication date: 1992-09-30
Anticipated expiration: 2012-03-09
Also published as: ATA46992A; JP2761323B2; DE4207917C2; FR2674131B1; DK24092D0; SE9200814D0; BE1006036A3; NL9200399A; DE4207917A1; JPH05123397A; ITMI913497A1; CH689484A5; IT1252672B; FR2674131A1; AT401144B; DK24092A; SE9200814L; MX9201160A; ES2028740A6; ITMI913497A0

Description

2254169 A FLOW REGULATOR AND A PROCESS FOR ITS MANUFACTURE This invention

relates to a flow regulator and a process for its manufacture and particularly although not exclusively relates to a device for controlling the flow in catheters and other similar equipment and a process for manufacturing the device.

It is common knowledge that the precise control of fluid to be administered by means of a catheter to a the human body presents major difficulties because of lb the small flow required to be controlled and which must be easily adjustable.

Several systems are known among which is that consisting of a progressive throttling of the tube either by a lateral or diametric compression or by the introduction of a body which effects the partial blockage of the tube. Also known is the method of longitudinal extension of the tube which closes in on an internal solid nucleus thus reducing the cross sectional passage for the fluid within the tube.

The systems currently known suffer from the disadvantage of a defective and erratic progression of the flow graduation in view of the small passage of flow and also the possibility of liquid particles being caught in these small passages thus changing the flow conditions after the flow has been adjusted to the required rate.

These problems result in a lack of reliability of the operation of the flow regulator during use, both with regard to flow rate and to flow conditions and in 1 consequence cause variations or inaccuracy in the administering of fluids during medical treatment.

The problems described above arise because the conventional method of varying flow rate by throttling the tube (e.g. by squeezing the walls together) only provides acceptable results with tubes of large internal diameter. In tubes with a very small hydraulic radius, squeezing the walls of the tube together results in extremely small interstices thus introducing all the defects indicated previously.

The present invention seeks to provide a device for regulating and controlling the flow in catheters and similar equipment designed to obviate the defects mentioned above.

According to the present invention there is provided a flow control device comprising a fixed bore giving a constant and regulated flow of high precision and which, contrary to the current practice, is non adjustable. By this means, applying a principle that is revolutionary in the application of flow control to catheters an absolute regularity of the bore is assured with a consequent permanently controlled flow for clinical treatment. In addition by using a circular or generally circular passage though of small diameter the transverse dimensions of the passage are maximized for a given hydraulic radius thus obviating the very small interstices currently obtained in present systems and which give rise to irregular operation or blockages.

According to another aspect of the present invention there is provided a process for manufacturing the above described flow regulator. This process is described in this specification in more detail and enables the production of tubes having bores with individual small dimensions and cross sections which are constant over the whole length. The process is industrially applicable and is inexpensive to carry out.

For a better understanding of the present invention and to show how it may be carried into effect reference will now be made by way of example to the accompanying drawings, in which:

Figure 1 is a longitudinal section through a flow regulator; Figure 2 is a longitudinal section through the flow regulator of Figure 1 taken along the line II-II; Figure 3 is a transverse section through the flow regulator of Figure 1 taken along the line III-III; Figure 4 shows a-length of tubing just prior to moulding; Figure 5 shows a length of tubing during moulding; Figure 6 shows a length of tubing after moulding, with a central flattened region and a precise internal bore; Figures 7 to 13 show various phases in the manufacture of the flow regulator of Figure 1; Figures 14 and 15 show a flow regulator connected to its associated feed tubes; and Figure 16 is a schematic view of the regulator in use during the clinical treatment of a patient.

Referring to the drawings, the flow regulator consists essentially of a single moulded piece shown generally as -1-, with tubular extremities -2and -3- and a central body -4- pierced with a hole of a precise diameter forming a bore -5- for regulating the flow. The said hole will preferably have a circular A cross -section or a section similar to circular in order to obtain the maximum transverse dimensions for a given hydraulic radius.

The central zone of the bored tube n5- is shown as flattened to facilitate manufacture but other exterior shapes would be acceptable always on condition that the interior bore remains cylindrical or of a general cylindrical form.

Manufacture of the piece which has the bore for passage of the fluid and the process for providing the said passage is shown schematically in figures 4,5 and 6 in which can be seen the tube -7- in its initial state with a calibrated pin er mandrel in its interior acting as a former -8: and exterior to the tube tooling -9- and -10- ready for hot pressing such that once the temperature of the plastic tube -7- attains a suitable temperature and its point of fluidity the press tools -9- and -10- will act on the tube as in figure 5, pressing on opposite sides of its exterior and causing the interior to adopt the form of the exterior of the calibrated mandrel -8-. Following the pressing operation of the tooling on the exterior of the tube -7by the formers -9- and -10- on its central zone--11- and an adequate cooling stage the former tools can be withdrawn and the mandrel extracted from the tube, leaving the tube in its final state for the operation of regulating the fluid to be administered. That is to say with its end sections or terminal lengths in simple tubular form as in the initial state and the central zone in some shape depending on the shape of the tooling such as flattened as -11- while causing 4111 r the interior -12- to adopt the form of the fluid passage required.

Figures 7 to 13 illustrate the successive phases of the manufacturing process for the device for regulating catheter flow shown schematically. The drawings show the initial tube -13- to be fed axially to the moulding press tool indicated genally as -14-, there being a guide piece -15oppos- an ing the extremity of the tube -13- carrying external expulsion or stripping collar -16-. The mandrel -17- is inserted axially into the guide member -15- as shown in figure 9, in which the man drel can be seen to be fully within the tube with its head -18- in contact with a flange or head ring -19- adjacent to the expulsion collar -16-.

Figures 10 and 11 show the stages of mould ing of -the central zone complete followed by cutting off the tube at a section -20- from the feed length from the guide -15-, with the entire regulating-dev ice in its finished state shown in figure 22 separated from the mould -14- and being finally detached by action of the expulsion collar -16- as in figure 13, which shows under the generic number -21- the finished device for regulating flow as disclosed in this patent.

The device is coupled up to union pieces -22 and -23- as in figure 14 and 15, for example, piece for accepting the supply tubing system -26- with piece -23- having a section -25- adaptable for conn ection of a needle or catheter to be applied to the patient, as shown in figure 15 and 16.

Graduation of the flow through the control device is governed both by the diameter and the length of the bore in the moulded zone of the device -21and by the height of the vessel containing the fluid -27- feeding through the supply tube -26- with respect to the level of the injection point -28where the catheter or needle is inserted into the vein of the patient. Variation of the liquid column is obtained by variation of the height of the vessel on a conventional support 10, column 29-.

In an alternative embodiment, the tube in its initial state is supplied to the press forming apparatus in short lengths, so that after the pressing and cooling operations are complete the finished flow regulator may simply be removed from the apparatus without the need for cutting it from a feed stock of tubing.

Claims

1. A flow regulator comprising a moulded component having inlet and outlet ducts between which a constriction is provided, the constriction comprising a moulded passage formed in a region of the component which has a flat external shape.

2. A flow regulator as claimed in claim 1 in which the moulded passage is of circular cross-section.

3. A flow regulator as claimed in claim 1 or 2 in which the inlet and outlet ducts are cylindrical with a circular outer cross-section.

4. A flow regulator for catheters and similar devices, the flow regulator comprising a moulded element having therein a passage of a precise diameter and length, this being part of a component having at its extremities tubing for the purpose of connecting the said passage of predetermined precise bore to the feed system, the characteristics of the calibrated precise passage being a function of the hydraulic radius of the said passage and selected accordingly.

5. A kit of parts comprising a plurality of flow regulators as claimed in any one of claims 1 to 4, each regulator having a bore of a different diameter, whereby a desired rate of flow can be achieved by selection of an appropriate one of the flow regulators.

6. A process for manufacturing a flow regulator comprising the steps of:

feeding a continuous tube in its initial state to a heating and moulding press, whilst simultaneously introducing a calibrated mandrel axially into the tube; moulding the zone of the tube corresponding to the position of the mandrel, such that the mandrel becomes fully imbedded in the mould material under a flattening operation; cooling the flow regulator thereby produced and withdrawing the mandrel; and cutting off the flow regulator from the tubing feed stock.

7. A flow regulator substantially as described herein with reference to and as shown in the 5 accompanying drawings.

8. A process for manufacturing a flow regulator, substantially as described herein, with reference to and as shown in the accompanying drawings.

1