Flow metering insert and/or device

1 . A flow metering insert for a drip chamber suitable for use in intravenous administration, the insert comprising:

a primary liquid flow channel comprising:

an inlet passage;

an outlet; and

a flow-resistant passage between the inlet passage and the outlet; and

a flow indicating channel in communication with the primary liquid flow channel between the inlet passage and the flow-resistant passage;

wherein the flow-resistant passage and the flow indicating channel is/are at least partially defined by one or more first recesses and/or open channels in a surface of the insert and, when the insert is inserted into a said drip chamber, the flow-resistant passage and the flow indicating channel are formed or located between the insert and a wall of the said drip chamber; and

wherein the flow-resistant passage provides a resistance to a liquid flow through the primary liquid flow channel such that liquid is forced into the flow indicating channel and reaches a level or height in the flow indicating channel proportional to the rate of liquid flow through the primary liquid flow channel.

2 . The insert of claim 1 , wherein the surface is a mating surface of the insert configured to mate with, contact and/or seal against the wall of the said drip chamber when the insert is inserted into the said drip chamber.

3 . The insert of claim 2 , wherein the mating surface is configured to conform to the interior surface of the drip chamber when the insert is inserted into the drip chamber, and/or comprises one or more sealing ribs that extend around the one or more recesses or open channels to seal against the interior surface of the wall of the drip chamber when the insert is inserted into the drip chamber.

4 . The insert of claim 1 , wherein the flow-resistant passage is substantially U-shaped when the insert is arranged substantially vertically, such that, when inserted into the said drip chamber and arranged substantially vertically, liquid remains in the flow-resistant passage when a liquid flow is stopped.

5 . The insert of claim 1 , further comprising an exit chamber in communication with an outlet end of the flow-resistant passage and the outlet for directing a liquid flow from the flow-resistant passage to the outlet and, wherein the exit chamber comprises a second channel extending from the outlet end of the flow-resistant passage configured to direct a liquid flow from the flow-resistant passage to the outlet without forming drops; and wherein the second channel is or comprises a second open channel formed at least partially in a sidewall of the exit chamber and extending to a floor of the exit chamber; and wherein the second channel is configured to draw liquid into the exit chamber by capillary action.

6 . The insert of claim 5 , wherein the exit chamber comprises the outlet and wherein the outlet end of the flow-resistant passage is positioned at a level or height above a level or height of the outlet when the insert is arranged substantially vertically; and wherein the outlet is located in a floor of the exit chamber.

7 . The insert of any of claim 6 , wherein the exit chamber further comprises an overflow outlet positioned at a level or height between the level or height of the outlet and the level or height of the outlet end of the flow-resistant passage.

8 . The insert of claim 1 , wherein the flow indicating channel comprises a graduated scale to provide a visual measure of the liquid level or height in the flow indicating channel and thereby the rate of liquid flow through the primary liquid flow channel; and wherein the flow indicating channel comprises a visible float to facilitate reading of the liquid level.

9 . The insert of claim 1 , wherein the flow indicating channel comprises:

an inlet end in communication with an outlet end of the inlet passage and an inlet end of the flow-resistant passage, and the flow indicating channel extends substantially upwardly from its inlet end when the insert is arranged substantially vertically; and

an open outlet end to permit an overflow; and/or

a notch or opening in a wall of the flow indicating channel at a position above the inlet end configured to permit a liquid flow out of the flow indicating channel.

10 . The insert of claim 9 , wherein the flow indicating channel comprises a graduated scale to provide a visual measure of the liquid level or height in the flow indicating channel and thereby the rate of liquid flow through the primary liquid flow channel; and wherein the flow indicating channel comprises a visible float to facilitate reading of the liquid level; and wherein at least a portion of the flow indicating channel extends from its inlet end at an angle to the vertical when the insert is arranged substantially vertically to increase the graduation spacing on the scale; and wherein the flow indicating channel is curved about a longitudinal and/or a transverse axis of the insert.

11 . The insert of claim 1 , wherein the outlet comprises a drip-forming orifice.

12 . The insert of claim 1 , further comprising: a vent channel in communication with, and extending substantially upwardly from, an outlet end of the inlet passage configured for venting bubbles in a liquid flow exiting the inlet passage before entering the flow indicating channel; and/or one or more filter elements located at or near the inlet end of the inlet passage.

13 . The insert of claim 2 , shaped and/or configured to provide an interference fit within the said drip chamber wherein the seal between the mating surface and the interior surface of the wall of the said drip chamber is provided by the interference fit; and, the insert comprising one or more ribs or projections extending away from the insert and configured to contact a wall of the said drip chamber when the insert is inserted into the said drip chamber to provide the interference fit.

14 . The insert of claim 1 , wherein the insert is formed of or comprises a substantially rigid or deformable material; and wherein the insert is or comprises a single piece moulding formed by an injection moulding process by a single direction injection moulding process.

15 . A flow meter device comprising the insert of claim 1 and a flow chamber for receiving the insert, the flow chamber comprising:

an opening through which the insert can be inserted;

an outlet for receiving a liquid flow from the outlet of the insert; and

one or more walls, at least one of the one or more walls including a substantially transparent portion for viewing the liquid level in the flow indicating channel.

16 . The device of claim 15 , further comprising a cover or lid connectable to the opening of the flow chamber, wherein the cover or lid comprises an inlet passage with an outlet end for connecting to the inlet passage of the insert and an inlet end for connecting to a liquid source; or wherein the flow chamber comprises an inlet passage with an outlet end for connecting to the inlet passage of the insert and an inlet end for connecting to a liquid source.

17 . The device of claim 16 , wherein the outlet end of the inlet passage of the cover/lid or flow chamber is connectable to the inlet passage of the insert by an interference fit; or

wherein the outlet end of the inlet passage of the cover/lid or flow chamber is connectable to the inlet passage of the insert by a sealing element; and wherein the sealing element comprises a filter element for filtering a liquid flow upstream of the insert, and wherein the flow chamber is or comprises an at least partially transparent drip chamber for use in intravenous administration.

18 . An intravenous administration set comprising:

an insert as defined in claim 1 ;

an at least partially transparent drip chamber for receiving the insert, the drip chamber comprising an outlet for receiving a liquid flow from the outlet of the insert;

tubing for connecting the outlet of the drip chamber to a point of administration; and

a flow control device.

19 . The intravenous administration set of claim 18 , further comprising a cover or lid for the drip chamber, the cover or lid comprising an inlet passage with an outlet end for connecting to the inlet passage of the insert and an inlet end for connecting to a liquid source, or wherein the drip chamber comprises an inlet passage with an outlet end for connecting to the inlet passage of the insert and an inlet end for connecting to a liquid source; and

wherein the outlet end of the inlet passage of the cover/lid or drip chamber is connectable to the inlet passage of the insert by an interference fit, and wherein the insert comprises a filter element located at or near the inlet end of the inlet passage of the insert; or

wherein the outlet end of the inlet passage of the cover/lid or drip chamber is connectable to the inlet passage of the insert by a sealing element; and wherein the sealing element comprises a filter element for filtering a liquid flow upstream of the insert.

20 . The insert of claim 3 , wherein the flow resistant passage comprises an orifice; and

wherein the orifice is located at or near a lower portion of the U-shaped flow-resistant passage when the insert is arranged substantially vertically.