GB2089944A

GB2089944A - Flow Regulating Device

Info

Publication number: GB2089944A
Application number: GB8138504A
Authority: GB
Original assignee: HG Wallace Ltd
Current assignee: HG Wallace Ltd
Priority date: 1980-12-23
Filing date: 1981-12-22
Publication date: 1982-06-30

Abstract

A device for regulating the flow of liquid under gravity in an infusion apparatus comprises a float chamber (1) having an inlet (3) an outlet (4), and a float (2) having a valve member (5) at its upper end. A manually operable valve (11) at or downstream of the outlet has a screw threaded valve member (12) held non-rotatably in a slot (15) to co-operate with a valve seat (16), the axes of the valve member and the seat extending in the axial direction of the float chamber. The valve (11) is adjustable manually by rotation of a control wheel (19). A member (27) adapted to be connected to a source of the liquid has a first passage (29) therein connected to the inlet and a second passage (28) therein for supplying air to the source of liquid and the float chamber throuqh a filter (22) from atmosphere via apertures (26) filter (32) adapted to admit and filter air from the atmosphere to the float chamber or said second passage and to admit and filter said filtered air to said second passage or said float chamber respectively. <IMAGE>

Description

SPECIFICATION Flow Regulating Device This invention relates to a device for regulating the flow of a liquid under gravity in an infusion apparatus.

A known device of this type comprises a housing defining a float chamber having an inlet and an outlet, a float in the chamber having a valve member at its upper end for closing the inlet when the liquid in the chamber has reached a predetermined level, and a manually operable valve for adjusting the cross-section of the outlet opening. The manually operable valve comprises a screw threaded valve shaft received in an internally threaded aperture extending radially of the housing. The valve shaft terminates in a conical or frusto-conical valve member which enters an aperture of circular cross-section, the valve shaft being rotatable by means of a thumb wheel. Such a device is described in German Offenlegungsschrifts Nos 2644 140 and 27 20 522 and in Arch. Surg.-Vol. 1 12, January 1977, pp 53 and 54.

Whilst such a valve enables a desired flow rate to be selected and maintained, it may permit air to leak between the screw threaded valve shaft and the internally threaded aperture, thus enabling air bubbles to enter the liquid, which is undesirable when the liquid is being supplied intravenously. It is also possible for bacteria to enter the liquid by this route. In addition, the valve may permit liquid passing through the device to stagnate, which is undesirable when infusing, for example, blood. Also any end float in the valve shaft, which is difficult to eliminate entirely, can cause erratic variations in the flow rate.

According to one aspect of the invention, there is provided a device for regulating the flow of liquid under gravity in an infusion apparatus, comprising a float chamber having an inlet for liquid at its upper end and an outlet for liquid at its lower end, a float in said chamber having a valve member at its upper end for closing said inlet when the liquid in the float chamber has reached a predetermined level, and a manually operable valve arranged at or downstream of the outlet, the manually operable valve comprising a tapered valve member co-operating with an apertured valve seat of corresponding cross-section, the axes of the valve member and the valve seat extending in the axial direction of the float chamber, either the valve member or the valve seat being directly or indirectly manually movable in said axial direction so as to vary the flow crosssection.

This form of manually operable valve thus retains the advantages of the valve of the prior art which permits accurate adjustment of the flow rate through the device, whilst avoiding the disadvantages. Thus, it is no longer possible for air from the atmosphere to leak between the valve shaft and the aperture in which it is mounted, since these are only open at the inlet end to the liquid in the float chamber.Owing to the vertical orientation of the valve member, any air present can escape upwardly into the float chamber. Furthermore, liquid cannot stagnate in the valve. The valve member is preferably conical or frusto-conical and the valve seat is preferably of circular cross-section.

In a preferred embodiment of the invention, the valve member is provided on a screw threaded valve shaft which is prevented from undergoing a substantial degree of rotation, the valve shaft being received in an internally threaded aperture provided either in a manually rotatable member or in a member rotated by a manually movable member. This arrangement allows for a fine setting of the flow rate, and only requires the sealing of a single face of the rotatable member provided the remaining face of the rotatable member is left open to the liquid in the float chamber. The rotatable member may for example be rotated via a worm or a gear wheel to allow increased sensitivity in the setting of the flow rate.

In an alternative arrangement, either the valve member or the valve seat may be provided on or in a member of circular cross-section having a pin extending radially outwardly therefrom, the pin passing through an angled slot in a housing member, whereby movement of the pin in the slot causes the member of circular cross-section to rotate and simultaneously to be raised or lowered, whereby the vertical distance between the valve member and the valve seat is also varied.

According to a second aspect of the invention, there is provided a device for regulating the flow of liquid under gravity in an infusion apparatus, comprising a float chamber having an inlet for liquid at its upper end and an outlet for liquid at its lower end, a float in said chamber having a valve member at its upper end for closing said inlet when the liquid in the float chamber has reached a predetermined level, a manually operable valve arranged at or downstream of the outlet, a member adapted to be connected to a source of the liquid and having a first passage therein connected to the inlet and a second passage therein for supplying air to the source of liquid, and a filter adapted to admit and filter air from the atmosphere to the float chamber or said second passage and to admit and filter said filtered air to said second passage or said float chamber respectively.

Thus, a single filter serves to allow filtered air to enter both the float chamber and the liquid source, whereby the float chamber and liquid source remain in use at substantially atmospheric pressure. Moreover, the air entering the liquid source or the float chamber is filtered twice.

In the accompanying drawings: Figure 1 is a section through a first preferred embodiment of a device according to the invention; Figure 2 is a section through the upper part of a modified embodiment of a device according to the invention; and Figures 3 and 4 are plan views of two filter supports forming part of the embodiment of Figure 2, Figure 3 being a top plan view of an upper filter support and Figure 4 being an underneath plan view of a lower filter support.

As shown in Figure 1, a device for regulating the flow of liquid under gravity in an infusion apparatus comprises a float chamber 1 containing a float 2. The float chamber has an inlet 3 at its upper end and an outlet 4 at its lower end. The float has a valve member 5 at its upper end for closing the inlet 3 when the liquid in the float chamber reaches a predetermined level.

A flow regulator body 6 is threaded onto the lower end of a float chamber housing 7 and has a drip chamber 8 secured thereto. A manually rotatable flow control wheel 9 is provided in the flow regulator body 6 and is secured to the float chamber 1 by means of spigots 10. The base 13 of the float chamber 1 has a threaded aperture therein which receives a threaded valve shaft 11 on which is provided a conical valve member 12.

The base 13 of the float chamber is seated to the body 6 by means of an O-ring 14. The valve shaft 11 has two opposed planar faces which cooperate with the sides of a rectangular slot 15 in the body 6 so as to prevent any substantial rotation of the valve shaft. The planar faces further provide flow passages through the threaded aperture in the base of the float chamber. The slot 15 terminates in a flow passage defined by a tapering valve seat 16.

Thus, when the control wheel 9 is manually rotated, the float chamber 1 is also rotated and, since the valve shaft is substantially prevented from rotation by its engagement with the rectangular slot 15, the valve shaft 11 is raised or lowered by means of the screw thread, hence varying the cross-section available for flow between the valve member 12 and the valve seat 16.

The lower end of the float 2 is provided with a guide shaft 17 which is seated in a recess 18 in the top of the valve shaft 11. The arrangement is such that the guide shaft 17 remains within the recess 18 in all positions of the float and valve shaft.

The upper end of the float chamber 1 is defined by an annular filter 19 sandwiched between support discs 20, 21. A further annular filter 22 is sandwiched between support discs 23, 24 and mounted in a cap 25 which is secured to the top of the housing 7. A plurality of apertures 26 are provided around the upper end of the housing 7 so as to admit air from the atmosphere into the space between discs 20 and 24. A plurality of apertures are provided in each of the support discs, whereby filtered air is admitted to the float chamber 1 and to the cap 25. The cap 25 is surmounted by spike 27 adapted to pierce a bag or bottle of liquid or to be inserted in a flexible tube connected to a source of liquid. A first passage 28 extends along the spike 27 tc allow the air to pass from the interior of the cap 25 into the bag or tube.A second passage 29 also extends along the spike 27 to conduct liquid into a particle filter chamber 30 containing a particle filter 31. The filtered liquid then descends under gravity to the inlet 3 of the float chamber.

Referring now to Figures 2 to 4, a second embodiment of a device for regulating the flow of a liquid under gravity is shown which is similar in many respects to that of Figure 1. The device differs from that of Figure 1 firstly in that the flow control wheel 9 is formed integrally with the float chamber 1 and at the upper end thereof. This arrangement avoids the necessity of providing spigot connections 10 between the flow control wheel and the float chamber. An O-ring 14' is arranged between the float chamber 1' and the housing 7' to prevent air from entering the liquid as it leaves the float chamber.

Secondly, the two filters and four support discs of Figure 1 are replaced by a single annular filter 32 sandwiched between two support discs 33,34. The upper support disc 33 comprises six air inlets 35 open to the atmosphere arranged around the periphery thereof, each of which is connected to a common annular channel 36. The upper support disc 33 further comprises six air outlets 37, for supplying air to the passage 28', each of which is connected to a common annular channel 38. The lower support disc 34 has a first, outer annular channel 39 which corresponds in diameter to the channel 36 and a second, inner annular channel 40 which corresponds in diameter to the channel 38. The channels 39, 40 are connected by six radially extending slots 41.

Thus, air is permitted to enter the float chamber by passing through the inlets 35, the annular channel 36, the filter 32, the annular channel 39 and the slots 41. Air can pass from the slots 41, through the annular channel 40, the filter 32, the annular channel 38 and the outlet 37 to enter the passage 28'. Thus, a single filter serves to filter both the air entering the float chamber and the air entering the bag or bottle from which the liquid is supplied. Moreover, the air entering the bag or bottle is filtered twice.

Claims

1. A device for regulating the flow of liquid under gravity in an infusion apparatus, comprising a float chamber having an inlet for liquid at its upper end and an outlet for liquid at its lower end, a float in said chamber having a valve member at its upper end for closing said inlet when the liquid in the float chamber has reached a predetermined level, and a manually operable valve arranged at or downstream of the outlet, the manually operable valve comprising a valve member cooperating with a valve-seat, the axes of the valve member and the valve seat extending in the axial direction of the float chamber, the cross-section of the valve member and/or the valve seat varying continuously in said axial direction, and either the valve member or the valve seat being directly or indirectly manually movable in said axial direction so as to vary the flow cross-section.

2. A device as claimed in claim 1, wherein the valve member is conical or frusto-conical and the valve seat is of circular cross-section.

3. A device as claimed in claim 1 or 2, wherein the valve member is provided on a screw threaded valve shift which is prevented from undergoing a substantial degree of rotation, the valve shaft being received in an internally threaded aperture provided either in a manually rotatable member or in a member rotated by a manually movable member.

4. A device as claimed in claim 3, comprising a worm or a gear wheel for rotating the rotatable member.

5. A device as claimed in claim 1 or 2, wherein the valve member or the valve seat is provided on or in a member of circular cross-section having a pin extending radially outwardly therefrom, the pin passing through an angled slot in a housing member, whereby movement of the pin in the slot causes the member of circular cross-section to rotate and simultaneously to be raised or lowered, whereby the vertical distance between the valve member and the valve seat is also varied.

6. A device for regulating the flow of liquid under gravity in an infusion apparatus, comprising a float chamber having an inlet for liquid at its upper end and an outlet for liquid at its lower end, a float in said chamber having a valve member at its upper end for closing said inlet when the liquid in the float chamber has reached a predetermined level, a manually operable valve arranged at or downstream of the outlet, a member adapted to be connected to a source of the liquid and having a first passage therein connected to the inlet and a second passage therein for supplying air to the source of liquid, and a filter adapted to admit and filter air from the atmosphere to the float chamber or said second passage and to admit and filter said filtered air to said second passage or said float chamber respectively,

7. A device as claimed in claim 6, wherein said manually operable valve is as defined in any of claims 1 to 5.

8. A device as claimed in claim 1, wherein said manually operable valve is constructed and arranged substantially as illustrated in Figure 1 of the accompanying drawings.

9. A device as claimed in claim 6, wherein said filter is constructed and arranged substantially as illustrated in Figures 2 to 4 of the accompanying drawings.

10. A device for regulating the flow of liquid under gravity in an infusion apparatus, substantially as herein described with reference to Figure 1 or Figures 2 to 4 of the accompanying drawings.