GB2297603A

GB2297603A - Gravity feed valve device

Info

Publication number: GB2297603A
Application number: GB9501928A
Authority: GB
Inventors: Douglas Mitchell Cumming
Original assignee: DOUGLAS MITCHELL CUMMING
Priority date: 1995-02-01
Filing date: 1995-02-01
Publication date: 1996-08-07
Anticipated expiration: 2015-02-01
Also published as: GB2297603B; GB9501928D0

Abstract

A valve device comprises a chamber 10 having an inlet 12, and an outlet in its lower region. The outlet has a valve seat 10d, which co-operates with a float member 18 having a body portion formed with a part-spherical undersurface 18a. The float member has a stem 18b projecting upwardly from its body portion, such that, in use, the float member 18 floats with its body portion substantially below the surface of a quantity of liquid contained in the valve device.

Description

Gravity feed valve device The present invention relates to a valve device for use in an arrangement which feeds liquid under gravity, and more particularly for use in an intravenous drip.

An intravenous drip comprises a bag of liquid (for example saline solution, blood, plasma etc.) coupled to a drip chamber from which a length of tubing extends to pass the liquid to the patient. The drip chamber includes a float member which comes to rest on a valve seat as the liquid empties from the bag and drip chamber, in order to prevent the delivery tubing from emptying: this accordingly prevents air from entering the patient, whilst the empty bag is removed and replaced. There is nevertheless a risk that some bubbles of air may pass into the delivery tubing, as the float member comes to rest on its valve seat, because the float member floats relatively high in the liquid and does not engage onto the valve seat until the liquid has dropped almost to the level of the valve seat.

We have now devised a valve device which overcomes the above-mentioned problem.

In accordance with this invention there is provided a valve device which comprises a chamber having an inlet, an outlet in a lower region of the chamber, said outlet being provided with a valve seat, and a float member having a body portion formed with a part-spherical undersurface for cooperating with said valve seat to close said outlet, said float member having a stem projecting upwardly from said body portion, such that in use said float member floats with its body portion substantially below the liquid surface.

In use of this device, the float member comes to rest on its valve seat whilst the liquid surface is still substantially above the level of the valve seat. Accordingly, the risk is avoided of air bubbles passing through the outlet before the float member is fully engaged with the valve seat.

Preferably the valve seat is generally hemispherical in shape, and complementary to the undersurface of the float member. Preferably the upwardly-projecting stem of the float member tapers.

Preferably the chamber has a relatively narrow, vertical duct portion which leads to the valve seat, and down which the float member is guided as the chamber empties.

Preferably the chamber has a sloping bottom wall, e.g. in the shape of the inverted cone, to guide the float member into the vertical duct portion. Preferably the device comprises a secondary chamber below the vertical duct portion, the secondary chamber having an outlet for coupling to a length of flexible tubing which passes the liquid to the patient.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a vertical section through a valve device in accordance with this invention, for an intravenous drip and when in normal use'; and FIGURE 2 is a similar section through the valve device showing the manner in which the valve member seats to close the outlet from the device as the drip chamber empties.

Referring to the drawings, there is shown a valve device for an intravenous drip, the valve device comprises a hollow body 10 having an inlet 12 at its top for coupling to a bag of liquid, and an outlet 14 at its bottom for coupling to a length of delivery tubing 16 to pass liquid to a patient.

The body 10 has upper and lower chamber 10a,10b. The upper chamber 10a has a sloping bottom wall, in the shape of an inverted cone, from which a reduced-diameter portion lOc projects to form a vertically extending duct. This duct portion lOc communicates at its lower end with the chamber lOb and is provided, adjacent its lower end, with a valve seat lOd of generally hemispherical shape. The valve device further comprises a float member 18 which has a body portion formed with a generally hemispherical undersurface 18a, and a tapering stem 18b projecting upwardly from the body portion.

The upper and lower chambers lOa,10b of the device are formed as a one-piece plastics moulding and are closed by caps 20,22 which are provided with extension tubes 21,23: in use, an outlet tube 24 of the bag of liquid to be delivered is coupled to inlet tube 21 and the delivery tubing 16 is coupled to the outlet tube 23. Preferably the body 10 of the device is transparent, so that the level of the liquid and the position of the float member can be seen.

In use, liquid from the supply bag passes into the upper chamber 10a through its inlet and then passes through the vertical duct 10c, the chamber 10b and the delivery tubing 16 to the patient. Normally, as shown in Figure 1, the float member 18 floats with its body portion wholly below the surface S of the liquid in the upper chamber 10a, and with its tapering stem 18b submerged to a greater or lesser extent, depending on the density of the liquid. Thus, at least for a substantial range of liquid densities, the hemispherical undersurface 18a of the float member 18 lies well below the surface S of the liquid.

Once the supply bag has emptied, the liquid gradually drains from within the upper chamber 10a, and the float member 18 falls with the level of the liquid. The float member 18 is guided into the vertical duct portion 10c of the device by means of the sloping bottom wall of the upper chamber 10a, then continues to drop down this duct portion 10c until it engages the valve seat 10d. This condition is shown in Figure 2, from which it will be seen that the outlet from the duct 10c has been closed whilst the liquid surface is still well above the valve seat 10d. This avoids the risk of air bubbles passing through the outlet of the chamber 10a.

It will be noted that the secondary or lower chamber 10b acts to hold a small reserve of the liquid, so that should any leakage occur in the valve, the reserve quantity of liquid effectively isolates the delivery tubing 16 from the air.

Claims

1) A valve device comprising a chamber having an inlet, an outlet in the lower region of said chamber, said outlet comprising a valve seat, and a float member comprising a body portion formed with a part-spherical undersurface for cooperating with said valve seat to close said outlet, said float member further comprising a stem projecting upwardly from said body portion, such that, in use, said float member floats with said body portion substantially below the surface of a quantity of liquid contained in said chamber.

2) A valve device as claimed in claim 1, wherein said valve seat is generally hemispherical and complementary to the undersurface of said float member.

3) A valve device as claimed in claim 1 or claim 2, wherein said upwardly projecting stem of said float member is tapered.

4) A valve device as claimed in any preceding claim, in which said chamber comprises a relatively narrow, vertical duct portion which leads to said valve seat, and down which said float member is guided as said chamber is emptied.

5) A valve device as claimed in claim 4, wherein said chamber comprises a sloping bottom wall for guiding said float member into said vertical duct portion as said chamber is emptied.

6) A valve device as claimed in claim 5, wherein said sloping bottom wall is in the form of an inverted cone.

7) A valve device as claimed in any preceding claim, comprising a secondary chamber, arranged below said vertical duct portion, and comprising an outlet for coupling to a length of tube.

8) A valve device as claimed in any preceding claim, wherein said inlet is arranged for coupling to a fluid supply bag.

9) A valve device as claimed in any preceding claim, comprising first, second and third sections, said first section comprising said inlet, said second section comprising said chamber, said vertical duct portion and said secondary chamber, and said third section comprising said secondary chamber outlet.

10) A valve device substantially as herein described with reference to the accompanying drawings.