Gas separation: processes – Selective diffusion of gases – Selective diffusion of gases through substantially solid...
Reexamination Certificate
2002-08-08
2004-06-08
Spitzer, Robert H. (Department: 1724)
Gas separation: processes
Selective diffusion of gases
Selective diffusion of gases through substantially solid...
C096S006000, C096S010000
Reexamination Certificate
active
06746514
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus, a system and method for venting a gas from a liquid delivery system. More specifically, the apparatus relates to a venting tube which may be implemented within a liquid delivery system. The venting tube has a liquiphobic membrane through which the gas may escape from the liquid delivery system through the venting tube without clogging of the membrane.
It is generally known to introduce liquids into the body, including medicaments and supplements, as well as bodily liquids, such as blood, plasma or the like. Often, a liquid delivery system is used to introduce these materials. The liquid delivery system may include a tube or other container which houses the liquid while the liquid is introduced into the body. Often, gas bubbles may form within the liquid. If the gas is introduced into the human body, the gas can be potentially harmful.
In some applications, hydrophobic membranes are incorporated into the liquid delivery system to vent the gas from the liquid delivery system. The membrane may be attached to a venting tube at an opening of the venting tube. The venting tube may be positioned along a path of the liquid prior to the liquid entering the body. The membrane may be gas permeable and may have pores through which gas may pass through the membrane into the venting tube. The gas may be present within the liquid or may be present within a chamber holding the liquid. The gas which enters the venting tube may then be vented from the system. The hydrophobic nature of the membrane prevents liquid from passing through the membrane. Accordingly, when the liquid contacts the membrane, gas escapes from the liquid and passes through the membrane. The gas may then be vented from the system.
However, a number of deficiencies exist with known systems and methods for removing gas from liquid delivery systems. For instance, known membranes incorporated along a liquid delivery path in a direction parallel to the path of the liquid are prone to clogging. For example, a liquid delivery system may use a liquid having glucose and/or ionic components. As gas from the liquid passes through the membrane, the glucose and/or the ionic components may accompany the gas and may become trapped within the pores of the membrane. The glucose and/or the ionic components may eventually infiltrate the membrane and may prevent venting of the gas from the liquid, resulting in a loss of hydrophobicity. Because the membrane is positioned parallel to the path of the liquid in known systems, the entire surface of the membrane is exposed to the liquid and becomes clogged during venting.
In other applications, liquid pressure may be non-constant, as seen in applications using a pump, such as a piston pump, for liquid delivery. Increases in pressure may cause, for example, pressure spikes which may damage the membrane and/or shorten the time that the membrane may be used within the system.
In addition, certain applications incorporate a mechanical float valve vent to vent the gas from the liquid delivery system. Often, these vents still require the use of a membrane within the system to prevent liquid contamination. Having a mechanical float valve and membrane substantially increases the cost associated with venting gas from the liquid delivery system. A need, therefore, exists for an apparatus, a system and a method for venting a gas from a liquid delivery system wherein the gas is vented through a liquiphobic membrane that is not prone to damage from pressure spikes or clogging
SUMMARY OF THE INVENTION
The present invention relates to an apparatus, a system and a method for venting a gas from a liquid delivery system. More specifically, the present invention relates to an apparatus that includes a venting tube positioned within a chamber. The chamber may hold a volume of liquid wherein the liquid has a top surface. Gas may be trapped within the chamber above the top surface of the liquid. Gas bubbles may be formed within the liquid as a result of dissolved gas coming out of solution due to, for example, movement of the liquid, change in liquid temperature or pressure, addition of liquid, or the like. These gas bubbles may be trapped in the upper portion of the chamber.
The venting tube may have walls defining an interior and an opening located at a bottom end of the venting tube. The opening may be covered by a liquiphobic membrane having a surface for contacting the fluid within the chamber. The membrane may prevent the liquid from entering the venting tube and may allow the gas trapped within the chamber to escape through the membrane into the venting tube for venting from the liquid delivery system. The membrane may be positioned along the venting tube at an angle wherein the membrane is not parallel to the top surface of the liquid within the chamber. As a result, the membrane may be less prone to clogging. The venting tube may also vent the gas independent of a position of the liquid in the chamber as long as the membrane is exposed to the gas, and a positive pressure exists within the liquid delivery system relative to ambient pressure.
To this end, in an embodiment of the present invention, a method for venting a gas from a liquid delivery system is provided. The method comprises the steps of: holding a liquid having a surface within a chamber having an interior wherein a portion of the chamber extends into the interior wherein the portion which extends into the interior forms a non-parallel surface to the surface of the liquid and further has a hole; and attaching a liquiphobic membrane to the portion of the chamber which extends towards the interior wherein the membrane is within the interior of the chamber and further wherein the liquiphobic membrane covers the hole.
In an embodiment, the method comprises the step of adding liquid to the interior of the chamber.
In an embodiment, the method comprises the step of removing the gas from the chamber.
In an embodiment, the method comprises the step of venting the gas through the hole in the portion of the chamber which extends towards the interior of the chamber.
In an embodiment, the liquiphobic membrane conforms to the shape of the non-parallel surface.
In an embodiment, the non-parallel surface is non-planar.
In another embodiment of the present invention, a method for venting a gas from a liquid delivery system is provided. The method comprises the steps of: providing a tube having walls defining an interior wherein the tube has an opening; attaching a gas-permeable membrane to the tube wherein the membrane covers the opening; and placing the tube to extend within a chamber having walls defining an interior wherein the chamber holds the liquid having a top surface within the chamber and further wherein the membrane defines a surface that is not parallel to the top surface of the liquid.
In an embodiment, the method comprises the step of adding liquid in the interior of the chamber.
In an embodiment, the method comprises the step of venting gas through the tube wherein the gas exits the tube exterior to the interior of the chamber.
In an embodiment, the method comprises the step of venting gas through holes in the walls of the tube exterior to the interior of the tube.
In an embodiment, the method comprises the step of providing a second opening in the tube wherein the second opening is covered by the membrane.
In another embodiment of the present invention, an apparatus for venting a gas from a liquid delivery system is provided. The apparatus has a tube having an interior defined by walls having a length defined between a first end and a second end wherein the tube has a top surface at the first end wherein the top surface defines a plane. An opening is provided at the second end of the tube wherein the opening defines a plane wherein the plane of the opening is not parallel to the plane of the top surface. Also provided is a membrane covering the opening of the tube wherein the membrane prevents the liquid from passing into the interior of the tube and allows the gas to enter in
Bedingfield John
Pan Li
Parish John A.
Baxter International Inc.
Bell Boyd & Lloyd LLC
Kelly Paula J. F.
Reagen Joseph P.
Spitzer Robert H.
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