GB1588266A - Anti-bubble safety valve - Google Patents

Description

(54) ANTI-BUBBLE SAFETY VALVE (71) I, EDouARD MALBEC, a citizen of the French Republic of, Logis de Chalonne, Le Gond Pontouvre, 16160 Charente, France do hereby declare the invention for which I pray that a patent may be granted to me and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to an anti-bubble safety valve for low pressure liquid flow, in particular for low-pressure flows of the type employed in medical applications and especially in perfusion.

In order to obtain a uniform flow of liquid, it is recommended practice to have recourse to a metering pump but it is then absolutely essential to prevent the formation of air bubbles in the injected liquid.

The present invention makes it possible to achieve this result in a simple and reliable manner by providing a valve which is cheap to produce and can thus be incorporated in singleuse perfusion lines which are intended to be delivered in sterile packages.

The anti-bubble safety valve in accordance with the invention essentially comprises a chamber for admission of liquid, a diaphragm forming part of the boundary of the chamber, an outlet pipe for the liquid, a valve seating surrounding the entrance to said outlet pipe and cooperating with the diaphragm; and a passageway to ambient atmosphere from a level in said chamber above the liquid outlet pipe entrance when the valve is in use, whereby liquid in said chamber when up to a level between said outlet pipe entrance and said passageway level flows into the interface between the seating and the diaphragm and passes by laminar flow towards the entrance to the outlet pipe whilst any air bubbles in the liquid in the chamber pass to the surface of the liquid and thence by said passageway to atmosphere.

It will be noted in addition that a valve of this type has the advantage of an intrinsic nonreturn action. At the same time, a predetermined limitation of any increase in the selected operating pressure is also obtained in a safe and reliable manner because of the passageway to the surrounding atmosphere.

In a form of construction which is particularly advantageous from the point of view of production and capital cost, the diaphragm is provided by a portion of the wall of a flexible bag which forms said chamber, the seating being constituted by a small plate to which the diaphragm is bonded.

Further distinctive features will become apparent from the following description of two embodiments of the invention which are given by way of example, reference being made to the accompanying drawings in which: Figure 1 is a front view in elevation of said valve; Figure 2 is a sectional view of said valve taken along line II-II of Figure 1; Figure 3 is an axial sectional view of another embodiment of the valve; Figure 4 is a view of said valve taken in the direction of the arrow IV of Figure 3, the valve cover and diaphragm having been removed.

The valve shown in Figures 1 and 2 is designed in the form of a flexible bag 1 of plastics constituted in this case by two sheets which have been heat-sealed around their periphery in such a manner as to form in addition a hook-attachment eyelet 2 at the top portion of the bag as well as an upper pocket 3, the function of which will be explained hereinafter.

The bottom edge of the bag is bonded to three pipes: one pipe 4 serves to admit the liquid into the bottom of the bag, the liquid being supplied, for example, by means of a metering pump (not shown); a second pipe 5 constitutes a valve outlet pipe which is intended to be connected to a perfusion needle, for example; a third pipe 6 forms a vent and extends to the top portion of the bag above the inlet level of the pocket 3. The outlet of said vent 6 will normally be fitted with a cottonwool plug 6a of the prescribed type.

The valve proper is constructed by means of a small plate 7 and a diaphragm 8 which is provided by a portion of a wall of the bag 1 and which, in this example, is bonded to the edge of the small plate by heat-sealing.

The small plate 7 thus forms a seating for the diaphragm surrounding a central entrance or duct 9 to which the outlet pipe 5 of the valve is connected. Around said central duct 9, the small plate is provided with a series of apertures or holes 10 disposed in spaced relation around the duct 9 so that the liquid which is present within the bag can pass through said holes, to spread over the interface between the diaphragm 8 and the small plate 7 and to pass towards the central duct 9 in laminar flow.

The mode of operation hereinabove described takes place in practice as follows.

When the liquid initially admitted into the bag via the pipe 4 reaches the level of the lower holes 10 of the small plate, said liquid has a tendency to spread by capillarity over the diaphragm 8/small plate 7 interface, thus "sticking" these latter to each other.

When the liquid reaches a predetermined height indicated for example by the line h in Figure 1, it then thrusts the diaphragm 8 away from the small plate 7 and begins to flow in the laminar state until a level equilibrium is established within the bag above the level of the duct 9. This equilibrium is dependent on the delivery of the feed pump which produces a flow into the outlet pipe 5.

If one or more air bubbles should happen to be introduced into the bag via the inlet pipe 4, said bubbles are normally carried away to the surface of the liquid which communicates with the surrounding atmosphere through the vent 6 and cannot in any event pass across the laminarflow interface formed between diaphragm 8 and small plate 7.

Should an obstruction occur for any reason at the level of the perfusion (for example when the needle has come out of a vein), the level of liquid within the bag will rise until it overflows into the pocket 3 which will take a certain time to fill, thus enabling the nursing staff to notice the defect.

In the event of filling of the bag above the top level of the pocket 3, the liquid can still flow out through the vent 6 and no excessive operpressure can consequently be applied within the valve outlet pipe.

A diaphragm valve of this type also has an intrinsic non-return action since the least reduction in pressure upstream of the holes 10 formed in the small plate tends to initiate closure of these latter by the diaphragm 8, with the result that any pulsations of the pump do not produce reverse flow of the liquid being delivered.

In another form of construction of the valve in accordance with the invention as shown in Figures 3 and 4, the valve comprises a body 11 which forms an annular admission chamber 12 provided with an inlet duct 13. Said chamber is partly delimited laterally by a diaphragm 14 in cooperating relation with a seating 15 which is located within the annular chamber surrounds the entrance to an outlet duct 16. In this example, the diaphragm 14 is gripped at the periphery of the annular chamber by an endcap 17 which is assembled with the body 11. A vent nozzle 18 is provided at the top of the chamber 12, the cross-sectional area of said nozzle being such that any bubble which may be introduced through the inlet duct 13 of smaller cross-sectional area may be readily permitted to escape. Said nozzle 18 is surmounted by a transparent tube 19 which permits observation of the height of liquid above the valve during operation and also serves as an overflow in the event that the pressure becomes excessive. Said tube can also be fitted with a cottonwool plug of the prescribed type.

The further possibility of adding a filter capsule 20 at the valve inlet has also been illustrated in conjunction with this embodiment.

Real microfiltering of the perfusion liquid can accordingly be obtained under the pressure of a feed pump and is superior to that which it is possible to obtain in a simple gravity-feed installation.

Another possibility which has also been illustrated consists in adding to the valve outlet pipe a drip-feed tube 21 which permits visual inspection of the liquid flow rate.

WHAT I CLAIM IS: 1. An anti-bubble safety valve for low pressure liquid flow comprising a chamber for admission of liquid, a diaphragm forming part of the boundary of the chamber, an outlet pipe for the liquid, a valve seating surrounding the entrance to said outlet pipe and cooperating with the diaphragm; and a passageway to ambient atmosphere from a level in said chamber above the liquid outlet pipe entrance, when the valve is in use, whereby liquid in said chamber when up to a level between said outlet pipe entrance and said passageway level flows into the interface between the seating and the diaphragm and passes by laminar flow towards the entrance to the outlet pipe whilst any air bubbles in the liquid in the chamber pass to the surface of the liquid and thence by said passageway to atmosphere.

2. A safety valve as claimed in Claim 1, wherein the diaphragm is provided by a portion of the wall of a flexible bag which forms the said chamber, the valve seating being constituted by a small plate to which the said diaphragm is bonded.

3. A safety valve as claimed in Claim 2, wherein the diaphragm is bonded to the edge of the small plate, the plate being provided in addition to the said outlet pipe entrance with at least one liquid-circulation aperture in spaced relation to the said outlet duct.

4. A safety valve as claimed in either Claim 2 or Claim 3, wherein the flexible bag is provided with suspension means and with three pipes at the base thereof, one pipe being provided for admission of the liquid into the bag, a second pipe being the outlet pipe communicating with the outlet pipe entrance in the small plate and the third pipe being arranged to form a vent and to extend to the top portion of said bag.

5. A safety valve as claimed in Claim 4, wherein the flexible bag has a pocket formed by bonding the bag walls to a level below that of the pipe which forms a vent so that the said bag constitutes a liquid overflow volume in the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. holes, to spread over the interface between the diaphragm 8 and the small plate 7 and to pass towards the central duct 9 in laminar flow. The mode of operation hereinabove described takes place in practice as follows. When the liquid initially admitted into the bag via the pipe 4 reaches the level of the lower holes 10 of the small plate, said liquid has a tendency to spread by capillarity over the diaphragm 8/small plate 7 interface, thus "sticking" these latter to each other. When the liquid reaches a predetermined height indicated for example by the line h in Figure 1, it then thrusts the diaphragm 8 away from the small plate 7 and begins to flow in the laminar state until a level equilibrium is established within the bag above the level of the duct 9. This equilibrium is dependent on the delivery of the feed pump which produces a flow into the outlet pipe 5. If one or more air bubbles should happen to be introduced into the bag via the inlet pipe 4, said bubbles are normally carried away to the surface of the liquid which communicates with the surrounding atmosphere through the vent 6 and cannot in any event pass across the laminarflow interface formed between diaphragm 8 and small plate 7. Should an obstruction occur for any reason at the level of the perfusion (for example when the needle has come out of a vein), the level of liquid within the bag will rise until it overflows into the pocket 3 which will take a certain time to fill, thus enabling the nursing staff to notice the defect. In the event of filling of the bag above the top level of the pocket 3, the liquid can still flow out through the vent 6 and no excessive operpressure can consequently be applied within the valve outlet pipe. A diaphragm valve of this type also has an intrinsic non-return action since the least reduction in pressure upstream of the holes 10 formed in the small plate tends to initiate closure of these latter by the diaphragm 8, with the result that any pulsations of the pump do not produce reverse flow of the liquid being delivered. In another form of construction of the valve in accordance with the invention as shown in Figures 3 and 4, the valve comprises a body 11 which forms an annular admission chamber 12 provided with an inlet duct 13. Said chamber is partly delimited laterally by a diaphragm 14 in cooperating relation with a seating 15 which is located within the annular chamber surrounds the entrance to an outlet duct 16. In this example, the diaphragm 14 is gripped at the periphery of the annular chamber by an endcap 17 which is assembled with the body 11. A vent nozzle 18 is provided at the top of the chamber 12, the cross-sectional area of said nozzle being such that any bubble which may be introduced through the inlet duct 13 of smaller cross-sectional area may be readily permitted to escape. Said nozzle 18 is surmounted by a transparent tube 19 which permits observation of the height of liquid above the valve during operation and also serves as an overflow in the event that the pressure becomes excessive. Said tube can also be fitted with a cottonwool plug of the prescribed type. The further possibility of adding a filter capsule 20 at the valve inlet has also been illustrated in conjunction with this embodiment. Real microfiltering of the perfusion liquid can accordingly be obtained under the pressure of a feed pump and is superior to that which it is possible to obtain in a simple gravity-feed installation. Another possibility which has also been illustrated consists in adding to the valve outlet pipe a drip-feed tube 21 which permits visual inspection of the liquid flow rate. WHAT I CLAIM IS:

1. An anti-bubble safety valve for low pressure liquid flow comprising a chamber for admission of liquid, a diaphragm forming part of the boundary of the chamber, an outlet pipe for the liquid, a valve seating surrounding the entrance to said outlet pipe and cooperating with the diaphragm; and a passageway to ambient atmosphere from a level in said chamber above the liquid outlet pipe entrance, when the valve is in use, whereby liquid in said chamber when up to a level between said outlet pipe entrance and said passageway level flows into the interface between the seating and the diaphragm and passes by laminar flow towards the entrance to the outlet pipe whilst any air bubbles in the liquid in the chamber pass to the surface of the liquid and thence by said passageway to atmosphere.

2. A safety valve as claimed in Claim 1, wherein the diaphragm is provided by a portion of the wall of a flexible bag which forms the said chamber, the valve seating being constituted by a small plate to which the said diaphragm is bonded.

3. A safety valve as claimed in Claim 2, wherein the diaphragm is bonded to the edge of the small plate, the plate being provided in addition to the said outlet pipe entrance with at least one liquid-circulation aperture in spaced relation to the said outlet duct.

4. A safety valve as claimed in either Claim 2 or Claim 3, wherein the flexible bag is provided with suspension means and with three pipes at the base thereof, one pipe being provided for admission of the liquid into the bag, a second pipe being the outlet pipe communicating with the outlet pipe entrance in the small plate and the third pipe being arranged to form a vent and to extend to the top portion of said bag.

5. A safety valve as claimed in Claim 4, wherein the flexible bag has a pocket formed by bonding the bag walls to a level below that of the pipe which forms a vent so that the said bag constitutes a liquid overflow volume in the

event of overpressure which prevents normal discharge of the liquid through the valve.

6. An anti-bubble safety valve for a lowpressure liquid flow, substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 or 3 and 4 of the accompanying drawings.