Flow metering insert, flow metering device, and intravenous administration set.

Abstract

Insert and / or flow measuring device. The present invention relates to a flow measuring insert (10) for a drip chamber (50) that is suitable for use in intravenous administration. The insert comprises: a primary liquid flow channel with an inlet, an outlet, and a flow-resistant passage between the inlet and the outlet; and a flow indicating channel communicating with the primary liquid flow channel between the inlet and the flow-resistant passage. The flow-resistant passage provides a resistance to liquid flow such that the liquid is forced into the flow indicating channel and reaches a height proportional to the rate of liquid flow through the primary liquid flow channel.The flow-resistant passage and flow indication channel are at least partially defined by one or more first recesses and / or channels in the insert such that the flow-resistant passage and flow indication channel are formed between the insert and a wall of the drip chamber when the insert is inserted into the drip chamber.

Description

1 / 74 Descriptive Report of the Invention Patent for: “FLOW MEASUREMENT INSERT, FLOW MEASUREMENT DEVICE AND INTRAVENOUS ADMINISTRATION SET” TECHNICAL FIELD

[001] The present invention generally relates to flow measuring devices and / or parts thereof suitable for the administration of intravenous solutions. Particularly, but not exclusively, the invention relates to a flow measuring insert for a drip chamber used in intravenous administration, a flow measuring device comprising the insert, and an intravenous administration set comprising the insert. FUNDAMENTALS OF THE INVENTION

[002] Intravenous (IV) administration systems are generally used to infuse various types of parenteral solutions into a patient. An IV administration system provides a means of controlling the sterile passage of a liquid (e.g., saline solution, glucose solution, etc.) from a rigid or flexible supply container, such as an IV bag, into a patient. Conventional IV administration systems feature a closed chamber with a mouthpiece outlet (a so-called drip chamber), creating droplets as the liquid flows. The purpose of the drip chamber is to allow the rate of Petition 870260053140, dated 01 / 06 / 2026, page 31 / 105 2 / 74 Liquid flow rate is calculated by counting the number of drops per unit of time. This can be time-consuming and inaccurate, since drop size is not constant, and converting drop time into liquid flow rate can be difficult. Several well-established flow meter designs have been adapted for use in IV fluid administration.

[003] Well-known variations of the rotamer design (e.g., US document 3587313A) employ a small sphere of appropriate specific gravity (usually larger than the liquid, although it may also be a float in some designs) positioned within a vertically arranged conical indicator chamber (or tube), with the liquid inlet at the smaller end at the bottom of the chamber. The sphere is pushed towards the larger cross-sectional area of ​​the indicator chamber as the liquid flows around the sphere, such that the position of the sphere is indicative of the liquid flow rate. While these devices allow for more precise regulation and adjustment of the flow rate, they are costly to manufacture due to the high tolerances required, as well as the potentially complex assembly of the components.

[004] Another type of flow measuring device is the reverse flow type, such as that disclosed in document US2479786A. The device in document US2479786A Petition 870260053140, dated 01 / 06 / 2026, page 32 / 105 3 / 74 employs a vertically arranged tube having a liquid inlet at the top and a short portion at the lower end curved backward upon itself to form an upward-extending portion (indicator chamber / tube) with an opening at its upper end. This arrangement is enclosed within a larger sealed housing (i.e., drip chamber) having an outlet to another tubing leading to the patient. A small orifice in the tube wall at the bend allows liquid to flow downward from the inlet into the drip chamber. The liquid flow, combined with the flow resistance caused by the orifice, causes the liquid level in the ascending portion to rise to a level proportional to the flow rate and thus serves as an indicator chamber / tube.This design is simpler than rotamere variants, but it is inaccurate at low flow rates, and it is difficult to manufacture multiple units with consistent geometry, further affecting calibration and accuracy.

[005] The device in document US4136692A uses a similar principle to that in document US2479786A, replacing the curved tube with two chambers / tubes (an inlet chamber and an indicator chamber) interconnected at their lower ends and enclosed within a larger sealed housing (the drip chamber) with an outlet to the patient. The small orifice in the document Petition 870260053140, dated 01 / 06 / 2026, page 33 / 105 4 / 74 US2479786A is replaced by highly accurate orifice discs of minimum thickness (approximately 0.001 in or 0.0254 mm). This is intended to minimize any effects of temperature and viscosity changes on measurement accuracy, but the design maintains a relatively complex assembly of small parts, resulting in higher manufacturing costs compared to standard IV administration systems.

[006] Another variation of the reverse flow design is disclosed in document US4291693A, in which the orifice disc of document US4136692A is replaced by a flow restrictor tube, wherein at least a portion of the flow restrictor tube is oriented such that the liquid passing through it moves upwards to help prevent trapping any air bubbles. Similar to documents US4136692A and US2479786A, the flow resistance caused by the flow restrictor tube causes the liquid level in the upward-directed indicator tube to rise to a level proportional to the flow rate. However, like the device in document US4136692A, the design remains relatively complex, resulting in higher manufacturing costs.

[007] Document US4523464A discloses another variation of the reverse flow type device that can be manufactured from thermoplastic materials. In particular, the Petition 870260053140, dated 01 / 06 / 2026, p. 34 / 105 The 5 / 74 device comprises a flow-restricted orifice at the lower end of the vertical inlet tube and indicator chamber, but the walls of the inlet tube and / or indicator chamber are formed by a closed housing wall. The device is relatively simple to manufacture compared to US4136692A and US4291693A documents; however, it still requires assembly and soldering of multi-component parts. Furthermore, it is not well suited for abrupt changes in flow rate and is designed for measuring liquid flow through a partially filled tube where the inlet tube is gravity-fed.

[008] Another variation of the reverse flow type device is disclosed in applicant EP3294379B1’s prior patent, in which the flow measuring device is formed from two separately molded parts that can be easily assembled by fitting one inside the other. A first part comprises the drip chamber, a second part comprises the inlet tube, and a substantially U-shaped flow restrictor passage and an indicator chamber are formed between the first and second parts when assembled. Although simple to manufacture and assemble, it still requires the molding of two custom-made parts.

[009] One objective of the present invention is to provide a Petition 870260053140, dated 01 / 06 / 2026, page 35 / 105 6 / 7 4 improved flow measurement device that is simpler to manufacture and assemble and more reliable than previous reverse flow type designs, yet is still comparable in cost and easier, faster and more accurate to use than standard IV delivery systems based on drop counting.

[0010] The aspects and embodiments of the present invention were conceived with the foregoing in mind. SUMMARY OF THE INVENTION

[0011] According to a first aspect of the invention, a flow measuring insert is provided that can be used with a drip chamber, for example, for use in intravenous (IV) fluid administration. The insert may comprise a primary fluid flow channel and a flow indicating channel. The primary fluid flow channel may comprise an inlet passage, an outlet, and a flow-resistant passage between the inlet and outlet passages. The inlet passage may be connectable to a fluid source, such as a fluid container or IV bag, for receiving a fluid flow. The flow indicating channel may be in communication with the primary fluid flow channel between the inlet passage and the flow-resistant passage. The flow-resistant passage provides resistance to fluid flow through it such that the fluid is forced Petition 870260053140, dated 01 / 06 / 2026, page 36 / 105 7 / 7 4 into the flow indication channel and reaches a level or height proportional to the liquid flow rate through the primary liquid flow channel, inlet passage and / or flow-resistant passage.

[0012] The insert can be used with and inserted within a standard, dimensioned, unmodified transparent drip chamber known in the art, for example, of a drip set or infusion set used in medicine and / or intravenous (IV) administration to form a flow measurement device. Such a drip chamber typically has smooth internal surfaces. In particular, the insert can be inserted into the upper portion of a standard drip chamber, for example, through an opening at its top end. The drip chamber can be substantially rigid or flexible. The level or height of liquid in the flow indication channel can therefore be visualized through the side wall / outer wall of the drip chamber.A cover or lid with a means for connecting the flow measuring device to a liquid source (e.g., an IV bag or container), such as a vented or non-vented standard spike, as is known in the art, can be attached to the drip chamber to close and seal the drip chamber and define a passage for liquid to flow from the liquid source. Petition 870260053140, dated 01 / 06 / 2026, page 37 / 105 8 / 74 up to the insert entry passage. In some drip chambers, the cover or lid may be integral with the drip chamber. For example, in a two-part drip chamber comprising an upper portion (e.g., having the peak) and a lower portion that are fastenable to each other to close and seal the drip chamber, the insert may be inserted into the upper portion through an opening at its lower end. Standard tubing, fittings, and / or flow controllers may be used downstream of the resulting flow measuring device. When inserted into said drip chamber and connected to a liquid source, the insert's flow indication channel provides a visual indication of the liquid flow rate, which is more direct, accurate, and reliable than drop-counting-based methods in an otherwise standard drip chamber without such an insert.The insert can therefore be adapted to existing standard IV administration systems to provide improved flow measurement at minimal cost and / or disruption for standard IV administration set manufacturing practices. Additionally, the insert outlet may comprise a drip-forming orifice, such that a flow of drops from the outlet may still be visible in the lower portion of the drip chamber as the liquid exits the insert, in accordance with ISO. Petition 870260053140, dated 01 / 06 / 2026, page 38 / 105 9 / 74 8536-4 (an international standard that determines that drops must be continuously visible in gravity-fed infusion equipment for medical use). The resulting flow metering device can be prepared in the same way as existing drip sets, which involves squeezing and releasing a flexible lower portion of the drip chamber (below the insert) to draw fluid through the primary fluid passage from the fluid source and expel air upwards into the fluid source.

[0013] The primary liquid flow channel and / or flow indication channel may be at least partially defined by the insert. The primary liquid flow channel and / or flow indication channel may be partially defined by the insert, such that the primary liquid flow channel and / or flow indication channel are completed / fully defined when the insert is inserted into the drip chamber. Alternatively, the primary liquid flow channel and / or flow indication channel may be fully defined by or in the insert.

[0014] The inlet passage may be or comprise a closed channel. The flow-resistant passage and / or the flow indication channel may be at least partially defined by the insert. The insert may Petition 870260053140, dated 01 / 06 / 2026, page 39 / 105 10 / 74 comprise one or more recesses and / or channels configured to define at least partially the flow-resistant passage and the flow-indicating channel. The one or more recesses and / or channels may be one or more first recesses and / or first channels (when opposed to a second recess or second channel, as defined later). The flow-resistant passage and / or the flow-indicating channel may be at least partially defined by the one or more recesses and / or channels in the insert such that, when inserted within the drip chamber, the flow-resistant passage and / or the flow-indicating channel are formed or located between the insert and (an interior surface of) a wall (e.g., a side wall or outer wall) of the drip chamber.

[0015] Where the flow-resistant passage and / or flow-indicating channel is / are partially defined by the insert, the flow-resistant passage and / or flow-indicating channel may be or comprise one or more recesses or open channels formed in a surface of the insert. The one or more recesses or open channels may be closed, sealed and / or completed by (an interior surface of) a wall (e.g., a side wall or outer wall) of the drip chamber when the insert is inserted into the drip chamber. This can greatly simplify manufacturing and thereby reduce the Petition 870260053140, dated 01 / 06 / 2026, page 40 / 105 11 / 74 cost of manufacturing the insert. For example, it can be manufactured within standard injection molding tolerances and can be used with standard drop chambers that are widely available and used in the technique.

[0016] The surface may be a contact surface and / or an external surface (i.e., facing substantially away from the insertion) of the insert. The contact surface may be configured to fit, i.e., contact / abut and / or seal the interior surface of a wall (e.g., side wall or outer wall) of the drip chamber when the insert is inserted into the drip chamber. The contact surface may be configured to conform to and / or contact an interior surface of a wall (e.g., side wall or outer wall) of the drip chamber when the insert is inserted into the drip chamber. The contact surface may be substantially smooth. Alternatively or additionally, the contact surface may be or comprise one or more sealing ribs extending around one or more recesses or open channels that partially define the flow-resistant passage and / or the flow indication channel.The contact surface and / or one or more sealing ribs may be configured to at least partially deform the interior surface of the wall and / or be... Petition 870260053140, dated 01 / 06 / 2026, page 41 / 105 12 / 74 less partially deformed by the inner surface of the wall to make a liquid-proof seal between them.

[0017] Where the flow-resistant channel and / or the flow-indicating channel is / are fully defined by the insert, the flow-resistant passage and / or the flow-indicating channel may be or comprise one or more closed channels, for example, defined by one or more recesses and / or channels. Such an insert would not depend on the geometry of the drip chamber to function (since the flow-resistant channel and / or the flow-indicating channel are internal passages / channels of the insert), and could therefore be used with arbitrarily shaped drip chambers, provided the insert could fit into them. Alternatively, the insert may itself form a self-contained flow measuring device, without needing to be inserted within a drip chamber.For example, where the formation and visualization of drips from the outlet are not required, the insert can be connected in-line with a liquid circuit to monitor and / or adjust a flow rate through it.

[0018] A liquid channel can mean a closed channel, an open channel, or a channel with one or more open and closed channel portions in the insert. A channel Petition 870260053140, dated 01 / 06 / 2026, page 42 / 105 13 / 74 closed means a channel with one or more channel walls that close off a flow of liquid through it. An open channel means a channel with at least a portion of a channel wall open and exposed to its immediate surroundings such that a flow of liquid through it is not completely closed (for example, it may be formed by a recess).

[0019] The insert can be configured, shaped, and / or dimensioned to provide an interference fit within the drip chamber. In particular, the insert can be configured, shaped, and / or dimensioned to provide an interference fit between the contact surface and the drip chamber wall. The interference fit can provide a liquid-tight seal between the contact surface and the drip chamber wall, to close and seal one or more open recesses or channels and fully or completely define the flow-resistant passage and / or the flow indication channel. Thus, additional sealing and / or bonding of the insert to the inner surface of the drip chamber wall is not required to provide a liquid-tight seal, which simplifies the assembly of the resulting flow measuring device.

[0020] The insert may be formed of, or comprise, a substantially rigid material. In this case, the insert Petition 870260053140, dated 01 / 06 / 2026, p. 43 / 105 14 / 74 may provide an interference fit within a substantially flexible / deformable portion of the drip chamber to provide a liquid-tight seal between them. Alternatively, the insert may be formed of or comprise a substantially flexible, deformable and / or compressible material. In this case, the insert may provide an interference fit within a substantially rigid portion of the drip chamber to provide a liquid-tight seal between them. Where the insert is formed of or comprises a substantially rigid material, the drip chamber wall may be substantially flexible or less rigid than the insert, such that the inner surface of the wall flexes or deforms at least partially to conform to the contact surface of the insert when the insert is inserted into the drip chamber.Alternatively, where the insert is formed of, or comprises, a substantially deformable material, the drip chamber wall may be substantially rigid, such that the contact surface of the insert deforms at least partially to conform to the inner surface of the side wall. In either case, the contact surface is configured such that it can conform (after deformation or non-deformation) to the final inner surface of the wall when the insert is inserted into the chamber. Petition 870260053140, dated 01 / 06 / 2026, page 44 / 105 15 / 74 drip.

[0021] The insert may be formed of or comprise a thermoformable material, such as a plastic and / or thermoplastic material. Exemplary materials include, but are not limited to: acrylonitrile butadiene styrene (ABS) or equivalent, polyvinyl chloride (PVC) or PVC-free equivalent, polyethylene, polycarbonate, nylon, polypropylene, polyurethane, ethylene vinyl acetate or any plastic permitted for use in intravenous applications. ABS or equivalent may be suitable for forming a substantially rigid insert. PVC or PVC-free equivalent may be suitable for forming a substantially flexible, deformable and / or compressible insert.

[0022] A flow measuring device comprising the insert may be configured to be disposed substantially and vertically in use, such that the liquid may flow downwards through the inlet passage under gravity. References to upper and lower below refer to this orientation.

[0023] The insert can have a length and a width. The length can be in a longitudinal (vertical) geometric direction / axis. The length can be in an insertion direction, the insertion direction corresponding to the direction in which the insert is inserted. Petition 870260053140, dated 01 / 06 / 2026, page 45 / 105 16 / 74 inside the drip chamber during assembly. The width may be in a transverse direction.

[0024] Although described above in the context of IV administration, the insert can also be used with, for example, in series with other flow devices, such as electronic pumps, to monitor and / or adjust a flow rate. As such, more generally, the insert can be used with and inserted within a liquid flow chamber or housing comprising an opening for receiving the insert and an outlet for receiving a liquid flow from the insert's outlet. The outlet may be arranged downstream of the insert's outlet. A flow measuring device may be formed by the insert and the flow chamber or housing. The insert may be configured to close and / or seal the flow chamber or housing. The insert may be configured to close and / or seal the opening of the flow chamber or housing.Alternatively, a cover or lid with a means for connecting the device to a liquid source may be used to close and seal the opening of the flow chamber or housing. Piping, flow fittings and / or flow controllers may be connected to / used downstream of the outlet of the flow chamber or housing. The flow chamber or housing may comprise one or more walls (e.g., side walls or outer walls) that... Petition 870260053140, dated 01 / 06 / 2026, page 46 / 105 17 / 74 define an internal volume, cavity, or space dimensioned to accommodate the insert. The wall(s) may extend from the opening in the insertion direction. At least a portion of the wall(s) of the flow chamber or housing may be substantially transparent such that the level or height of liquid in the flow indication channel can be visualized through the wall. The internal volume, cavity, or space of the flow chamber or housing may have a substantially circular horizontal cross-section (e.g., the interior of the drip chamber may be substantially cylindrical) or have a non-circular and / or arbitrary horizontal cross-section. The interior surface of the wall(s) may be conical (internally) or non-conical in the insertion direction. The flow chamber or housing may be substantially tubular. The flow chamber or housing may be or comprise a tube or tubular member.The flow chamber may be or comprise a container or bag having an opening, portion and / or tubular portion, configured to receive and / or accommodate the insert, such that the insert may provide a visual indication of the flow rate within and / or through the container / bag / chamber. The exterior of the flow chamber or housing may have a regular or irregular shape. For example, the insert may be used for placement in a catheter bag to monitor the flow rate. Petition 870260053140, dated 01 / 06 / 2026, page 47 / 105 18 / 74 urinary. In other words, the insert geometry can be configured to fit many different flow chamber geometries and is not limited by application.

[0025] Alternatively, where the flow-resistant passage and / or flow-indicating channel are partially defined by the insert, a collar or ring may be used to close and / or seal the one or more open recesses or channels. The collar or ring may extend at least partially around the insert and at least partially the length of the insert. For example, when the insert is inserted within the collar or ring, or the collar or ring is positioned at least partially around the insert, the flow-resistant passage and / or flow-indicating channel may be formed between the insert and (an interior surface of) a wall (e.g., side wall) of the collar or ring, for example, as described above.A flow measuring device can be formed by the insert and collar / ring alone, or the insert and collar / ring can be inserted inside a drip chamber or flow chamber to form the flow measuring device (in the latter case, the wall of the drip / flow chamber does not close and seal the one or more open recesses or channels). Piping, flow fittings and / or flow controllers can be connected to / used downstream from the insert outlet. Petition 870260053140, dated 01 / 06 / 2026, page 48 / 105 19 / 74

[0026] The inlet passage of the insert may have an inlet end (upper end) and an outlet end (lower end). The upper end of the inlet passage may comprise an opening for receiving a liquid flow.

[0027] The lower end (outlet end) of the inlet passage may be in communication with one or more recesses or open channels on the outer / contact surface of the insert that partially define the flow-resistant passage and / or the flow indication channel. The insert outlet may be in communication with (an outlet end) of the flow-resistant passage.

[0028] The flow indication channel may comprise an inlet end communicating with an inlet end of the inlet passage and an inlet end of the flow-resistant passage. The flow indication channel may extend substantially upward from its inlet end (lower end) to an open outlet end (upper end) when the insert is disposed substantially vertically.

[0029] The operation / use of the insert depends on the principle that the liquid level / height in the flow indicating channel is proportional to the liquid flow rate through the flow-resistant passage. The change in the level / height of the Petition 870260053140, dated 01 / 06 / 2026, page 49 / 105 20 / 74 liquid flow rate is determined by the flow resistance provided by the flow-resistant passage. For example, for a given flow rate, greater flow resistance results in a higher liquid level / height in the flow indication channel. The flow indication channel may include a graduated scale to provide a visual measure of the liquid level or height in the flow indication channel and thus the liquid flow rate through the flow-resistant passage (and / or the inlet passage and / or primary liquid flow channel). The scale includes graduations or indices spaced at given intervals corresponding to given flow rate ranges. A visible float may be provided to facilitate reading the liquid level / height.

[0030] At high flow rates, the liquid level / height may exceed the height of the flow indicating channel. The open outlet end of the flow indicating channel may provide an overflow to allow the liquid to continue to flow freely through the resulting flow measuring device under high flow conditions (e.g., greater than 250 ml / hour).

[0031] The flow indication channel may be substantially straight, curved and / or comprise one or more curves. The flow indication channel may extend substantially and vertically from its Petition 870260053140, dated 01 / 06 / 2026, page 50 / 105 21 / 74 input end when the insert is arranged vertically. Alternatively, at least a portion of the flow indication channel may extend from its inclined input end (a non-zero angle) to the vertical when the insert is arranged substantially vertically (or at an angle to the longitudinal geometric axis of the insert). The angle may be in the range of substantially 5-85 degrees from the vertical (or the longitudinal geometric axis), or 10-80, or 15-75, or 20-70, or 25-65, or 30-60, or 35-55 degrees, or any combination or subrange thereof. Inclining at least a portion of the flow indication channel means that the vertical component of the scale is represented at an angle.This spreads the vertical components of the scale over a greater distance (i.e., increasing the absolute spacing / separation between the given graduations / increments) which can make the liquid level / height easier to measure / read and / or provide space for additional sub-graduations, thus increasing the scale resolution. This can be particularly useful at or near the inlet end of the flow indication channel where the liquid level / height corresponds to low flow rates (e.g., below 50 ml / hour). The flow indication channel can be curved about the longitudinal geometric axis of the insert and / or about a transverse geometric axis of the insert. Petition 870260053140, dated 01 / 06 / 2026, p. 51 / 105 22 / 74 For example, the flow indication channel may curve away from the longitudinal geometric axis, for example, when viewed from the side of the insert. Where the inner surface of the drip chamber wall is curved (i.e., about the longitudinal geometric axis of the insert), an angled flow indication channel may also be curved (i.e., about the longitudinal geometric axis of the insert), for example, it may be substantially helical in shape. An angled and / or curved flow indication channel may allow the insert length to be reduced, for example, to fit a smaller flow / drip chamber.

[0032] The flow indication channel may comprise a first portion and a second portion arranged at different angles. The first portion may be a lower portion extending from the inlet end of the flow indication channel inclined towards the vertical (or the longitudinal geometric axis) when the insert is arranged substantially and vertically, as described above. The second portion may be an upper portion extending substantially and vertically from the first portion when the insert is arranged substantially and vertically. Alternatively, the second portion may extend from the first portion inclined towards the vertical (or the geometric axis). Petition 870260053140, dated 01 / 06 / 2026, p. 52 / 105 23 / 74 longitudinal), where the angle is smaller (that is, closer to the vertical or the longitudinal geometric axis) than the angle of the first portion / lower portion.

[0033] The change in liquid level or height in the flow indication channel with changes in flow rate may be dependent on the geometry and / or volume of the flow indication channel. The smaller the volume, the faster the rate of change and / or responsiveness of the level / height to changes in flow rate and vice versa.

[0034] Alternatively or additionally, one or more notches or openings may be formed in a wall of the flow indication channel configured to allow liquid flow out of the flow indication channel. As the liquid level in the flow indication channel reaches the notch position and / or rises above the notch, some liquid may escape (into the drip chamber) through the notch. This means that much higher flow rates are required for the liquid level in the flow indication channel to continue rising above the notch position, because the rise in level must also overcome the fluid loss through the notch. This provides a non-uniform scale, with more flow sensitivity below the notch, and less flow sensitivity above it. Where there is more than one notch, each notch may be positioned at a different level. Petition 870260053140, dated 01 / 06 / 2026, page 53 / 105 24 / 74 different in the flow indication channel. Such a non-linear scale may be desirable in cases where greater flow measurement accuracy is required at lower flow rates, but the same flow meter must also measure high flow rates. A linear scale in such cases may be impractically large.

[0035] A flow-resistant passage has a cross-section and / or length sufficient to provide the required flow resistance. The flow-resistant passage may have a uniform or non-uniform width / cross-section for flow. The flow-resistant passage may comprise an orifice. The use of an orifice restriction (instead of an elongated restriction, such as a narrow tube / tube section) can make the mounted flow measuring device less susceptible to changes in liquid viscosity. The more resistance in the flow-resistant passage is provided by an orifice restriction, the less susceptible the flow rate measurement is to changes in liquid viscosity. The more resistance is provided by a narrow flow tube (e.g., in the case of an elongated restriction), the more susceptible it is to changes in liquid viscosity.Therefore, preferably, the orifice is as short as possible in the flow direction (within the constraints of the manufacturing process). A recess or channel wall. Petition 870260053140, dated 01 / 06 / 2026, page 54 / 105 A 25 / 74 opening partially defining the flow-resistant passage may comprise a projection pointing or extending into the passage or toward the center of the passage to narrow the width of the flow-resistant passage. The projection may extend from a floor of the recess and oppose the wall of the drip chamber. Additionally or alternatively, the projection may extend from a side wall of the recess or flow-resistant passage toward an opposite side wall of the recess or flow-resistant passage. The orifice may be formed by a single projection, for example, the projection may oppose a substantially straight portion of the wall (e.g., a wall of the recess or the wall of the drip chamber) or the orifice may be formed by two opposing projections. The projection(s) may be substantially rectangular, V-shaped, or triangularly shaped in cross-section.The more acute the angle θν of the side walls forming the projection, the more ideal the orifice becomes and the less susceptible the flow measurement device is to changes in liquid viscosity. V-shaped projections are a compromise between performance and manufacturability.

[0036] The width of the orifice may provide sufficient resistance to liquid flow to result in a discernible change in the liquid level / height in the indicator chamber. Petition 870260053140, dated 01 / 06 / 2026, page 55 / 105 26 / 74 flow when a flow rate through the flow-resistant passage is substantially between 0 - 250 ml / hour. The orifice width may be in the range of substantially between 0.1-0.2 mm.

[0037] The change in liquid level / height in the flow-indicating channel with flow rate through the flow-resistant passage is determined by the orifice dimensions. For example, for a given flow rate, a higher liquid level / height is achieved with narrower orifices. As such, the orifice dimensions can be chosen according to the application: based on the length, angle and / or height of the flow-indicating channel; the desired range of measurable flow rates from the liquid level / height in the flow-indicating channel; and / or the desired measurement resolution. For example, for a flow-indicating channel with a given maximum height, the maximum measurable flow rate (before the liquid overflows its upper end) is greater for wider orifices than it is for narrower orifices.However, a higher resolution scale (i.e., with indices / gradations at smaller flow rate intervals) can be used with narrower orifices. Similarly, where the flow indication channel is angled, a wider orifice can be used due to the spreading of the vertical components of the scale. Petition 870260053140, dated 01 / 06 / 2026, page 56 / 105 27 / 74

[0038] The flow-resistant passage may be shaped such that, when the insert is inserted within the dripping chamber and disposed substantially vertically, the liquid remains in the flow-resistant passage when the liquid flow is interrupted. The flow-resistant liquid passage may be substantially U-shaped when the insert is disposed substantially vertically. In this context, “U-shaped” means that the direction of liquid flow is substantially reversed as it passes through the flow-resistant passage (including V-shaped, C-shaped, etc.). As such, the flow-resistant passage includes a portion in which the liquid flows substantially upwards when the insert is disposed substantially vertically. The flow-resistant passage may also comprise additional turns and / or bends.

[0039] The substantially flow-resistant U-shaped passage ensures that when the liquid flow is interrupted by the operator, the flow-resistant passage does not dry out and remains moist. This can prevent the accumulation of solid deposits in the flow-resistant passage that can occur from liquid evaporation, which can affect the cross-sectional area of ​​the flow-resistant passage and thus the flow resistance, introducing error in the measurement of the liquid flow rate from the indicating channel. Petition 870260053140, dated 01 / 06 / 2026, page 57 / 105 28 / 74 flow.

[0040] Where the flow-resistant passage comprises an orifice, the orifice may be located in or near the lower portion of the U-shaped flow-resistant passage when the insert is disposed substantially vertically. This can ensure that the orifice is submerged in use (preventing the orifice from drying out), and that droplets do not form during the restricted part of the liquid flow. Avoiding droplet formation can improve the reliability of the resulting flow measuring device, since droplets cannot be consistent in volume or rate of formation.

[0041] The insert can be formed by a molding process, such as injection molding. In particular, the insert can be a one-piece mold. Optionally or preferably, the insert can be formed by a one-way injection molding process. The one-way molding process means that the mold that creates the insert consists of two parts, separated in a single direction (i.e., with no side core or complex tooling required). In this way, manufacturing time and cost are reduced. Additionally, since a flow-resistant passage can be formed between the insert and (an inner surface of) a drip chamber wall, the critical geometry and dimensions of the Petition 870260053140, dated 01 / 06 / 2026, page 58 / 105 29 / 74 Flow-resistant passages (e.g., the orifice) can be achieved with standard injection molding techniques and tolerances. For example, the entry passage can be formed at an angle to the vertical when the insert is arranged substantially vertically (or inclined to the longitudinal geometric axis), such that the exit end of the entry passage extends to an external surface of the insert and / or is in communication with one or more recesses or open channels on the external surface of the insert. Alternatively, the insert can be formed using a three-dimensional printing or machining process.

[0042] Devices that rely on the same principle of a liquid level or height in an indicator column being proportional to the flow through a flow-resistant passage have thus been unreliable until now at low flow rates (below 50 ml / hour), and / or have required high tolerances and onerous manufacturing costs. The insert of the present invention allows for improved accuracy and consistency of the indicated flow, even at low flow rates, can be manufactured within standard injection molding tolerances, and can be used with standard drip chambers widely available and used in the art.

[0043] The insert may also comprise a chamber of Petition 870260053140, dated 01 / 06 / 2026, page 59 / 105 30 / 74 outlet for directing a liquid flow from the flow-resistant passage to the outlet. The outlet chamber may be in communication with an outlet end of the flow-resistant passage and the outlet. The outlet chamber may comprise the outlet. The outlet chamber may comprise an opening in a side wall that is in communication with the outlet end of the flow-resistant passage. The side wall opening and / or outlet end of the flow-resistant passage may be positioned at a level or height above the level / height of the outlet when the insert is arranged vertically. The outlet chamber may comprise a floor, base, or bottom wall in which the outlet is located.

[0044] The outlet chamber may comprise a channel extending from the side wall opening and / or outlet end of the flow-resistant passage to direct and / or guide a flow of liquid from the flow-resistant passage to the outlet without forming droplets. The channel may be a second channel. The channel may be configured to draw liquid (e.g., substantially downwards) into the outlet chamber by capillary action. The channel may be or comprise an open or recessed channel formed at least partially in a side wall of the outlet chamber. The open channel may extend to the floor, base, or bottom wall of the chamber. Petition 870260053140, dated 01 / 06 / 2026, page 60 / 105 31 / 74 exit.

[0045] The outlet chamber may be at least partially defined by the insert. The outlet chamber may be partially defined by the insert such that, when the insert is inserted into the drip chamber, the outlet chamber is formed between the insert and a wall (e.g., a side wall or outer wall) of the drip chamber. The outlet chamber may be formed by a recess in the insert. At least a portion of the recess may be closed by the wall (e.g., a side wall or outer wall) of the drip chamber when mounted. The wall of the drip chamber may form at least a portion of a side wall of the outlet chamber.

[0046] The outlet chamber may further comprise an overflow opening positioned at a level or height between the outlet level / height and the level / height of the side wall opening and / or outlet end of the flow-resistant passage. When inserted within the drip chamber, the overflow opening may communicate with the lower portion of the drip chamber below the insert, such that liquid overflowing the outlet chamber may be drained into the lower portion of the drip chamber. This may prevent liquid from filling the outlet chamber which would otherwise introduce error in the flow rate measurement. Petition 870260053140, dated 01 / 06 / 2026, p. 61 / 105 32 / 74 particularly the “zero line”, from the flow indication channel. The overflow opening may also allow air to flow between the outlet chamber and the lower portion of the drip chamber. Furthermore, the outlet chamber may comprise one or more ventilation openings located above the level / height of the overflow outlet and communicating with the interior of the drip chamber to allow air to flow between the outlet chamber and the rest of the drip chamber. In this way, the outlet chamber may be an open chamber.

[0047] The insert may be further shaped and configured to provide a gap between the insert and the wall of the drip chamber. The gap may extend the length of the insert. The gap may be provided on a chamfered side of the insert, or a channel or recess. The overflow opening, gap and / or vent opening(s) may prevent air blockages in any / all passages / channels / chambers not filled with liquid and allow the resulting flow measuring device to be prepared in the same manner as existing drip assemblies, which involves squeezing and releasing a flexible portion of the drip chamber (the lower portion) to draw liquid through the primary liquid flow passage from the liquid source and expel air upwards into the liquid source. Petition 870260053140, dated 01 / 06 / 2026, page 62 / 105 33 / 74

[0048] The insert may further comprise one or more lateral ribs, panels and / or projections extending from the insert towards the outer wall of the drip chamber. The one or more lateral ribs and / or projections may serve to encourage a tight interference fit within the drip chamber and increase the structural strength / rigidity of the insert, for example, resistance to bending, flexing and / or twisting of the insert. The one or more lateral ribs and / or projections may extend in a substantially longitudinal and / or transverse direction. The lateral ribs or projections may comprise one or more openings or notches configured to prevent air or liquid from being trapped.

[0049] The insert may further comprise a filter element positioned upstream of the flow-resistant passage to prevent particles in the liquid from being deposited in the flow-resistant passage which would otherwise adversely affect the reliability of the resulting flow measuring device. The filter element may be positioned at or near the inlet end of the inlet passage. The filter element may be molded into / in the inlet passage.

[0050] The insert may further comprise a vent channel or bubble vent channel in fluid communication with the lower / outlet end of the passage. Petition 870260053140, dated 01 / 06 / 2026, page 63 / 105 34 / 74 inlet configured for venting any bubbles in the liquid flow exiting the inlet passage before they reach the flow indication channel. The vent channel may have a lower end in fluid communication with the lower / outlet end of the inlet passage and an open upper end. The lower end of the vent channel may be located upstream of the lower end of the flow indication channel. The vent channel may run substantially parallel to and / or alongside the flow indication channel. The vent channel may extend in a direction substantially parallel to the longitudinal geometric axis of the insert. The vent channel may extend substantially vertically from its lower end when the insert is arranged substantially vertically.The vent channel is configured to allow any bubbles in the liquid flowing out of the inlet passage to rise upwards in the vent channel and not enter the flow indication channel, which would otherwise adversely affect the flow measurement. The upper end of the vent channel may be at least the same height as the upper end of the flow indication channel. This can prevent excess / overflow of fluid (bubbles and liquid) from the vent channel affecting the flow measurement. Petition 870260053140, dated 01 / 06 / 2026, page 64 / 105 35 / 74 any liquid levels higher than the upper end of the vent channel in the flow indication channel.

[0051] According to a second aspect of the invention, a flow measuring device is provided comprising the insert of the first aspect and a flow chamber or housing for receiving the insert.

[0052] The flow chamber or housing may comprise an opening through which the insert may be inserted and an outlet for receiving a flow of liquid from the insert outlet. The flow chamber outlet may be disposed downstream of the insert outlet for connection to other components such as piping, fittings and / or flow controllers downstream of the device. The flow chamber may comprise one or more walls (e.g., side walls or outer walls). The insert characteristics defined with reference to a wall of a drip chamber in the first aspect may also be defined with reference to the wall(s) of the flow chamber. The wall(s) may define an internal volume, cavity or space dimensioned to accommodate the insert. The wall(s) may extend from the opening in the insertion direction. At least one of the one or more walls may comprise a substantially transparent portion for viewing the Petition 870260053140, dated 01 / 06 / 2026, page 65 / 105 36 / 74 liquid level / height in the flow indicator channel.

[0053] The internal volume, cavity, or space of the flow viewing chamber may be substantially circular in cross-section (e.g., the interior of the flow chamber may be substantially cylindrical) or have a non-circular and / or arbitrary cross-section. The flow chamber or housing may be or comprise a tube or tubular member. The flow chamber may be or comprise a container or bag having an opening, portion, and / or tubular portion, configured to receive and / or accommodate the insert, such that the insert may provide a visual indication of the flow rate into and / or through the container / bag / chamber. The interior surface of the wall(s) may be conical (internally) or non-conical in the insertion direction. The wall(s) of the drip chamber may be substantially rigid or flexible / deformable, or comprise a substantially rigid portion and a substantially flexible / deformable portion.The flow chamber or housing may be substantially tubular. The exterior of the flow chamber or housing may have a regular or irregular shape.

[0054] The flow chamber may be or comprise a drip chamber, such as a standard (at least partially) transparent drip chamber used in IV administration / drip sets known in Petition 870260053140, dated 01 / 06 / 2026, p. 66 / 105 37 / 74 technique. However, it will be appreciated that any flow chamber with suitable dimensions can be used, particularly for non-IV applications.

[0055] The flow chamber may have a length greater than the length of the insert. Where the flow chamber is a drip chamber for IV administration, it may have a length at least 40 mm greater than the length of the insert and the insert outlet may be positioned at least 5 mm from (an inner surface of) the wall of the drip chamber, to comply with ISO-8536-4.

[0056] The drip chamber may have a length of approximately 100 mm. The insert may have a length of approximately 60 mm. This may leave a usable reading scale of about 40 mm for the flow indication channel.

[0057] The flow chamber may be a single piece and comprise two or more separate portions that are attachable to each other. The opening for receiving the insert may be formed at an upper end of the flow chamber. The device may further comprise a cover or lid connectable to the flow chamber with a means for connecting the device to a liquid source (such as an IV bag or container). The cover or lid may be connectable to the opening of the flow chamber. The cover Petition 870260053140, dated 01 / 06 / 2026, page 67 / 105 38 / 74 or a cover or lid can close and seal the flow chamber and define an inlet passage for liquid flow from the liquid source to the insert's inlet passage. The cover or lid may comprise an inlet passage with an outlet end for connection to the insert's inlet passage and an inlet end for connection to a liquid source.

[0058] Alternatively, the cover or lid may be integral with the flow chamber. The flow chamber may comprise an inlet passage with an outlet end for connection to the insert's inlet passage and an inlet end for connection to a liquid source. In this case, the opening for receiving the insert may be a lower end of the flow chamber. The flow chamber may comprise a separate upper and lower portion that are attachable to each other. The upper portion may comprise the inlet passage. The lower portion may comprise the outlet. The opening for receiving the insert may be formed at the lower end of the upper portion.

[0059] An outlet end of the cover or inlet passage of the lid or flow chamber may be connectable and / or sealable to the (upper / inlet end of) inlet passage of the insert, for example, to prevent leaks and / or air from the inlet into Petition 870260053140, dated 01 / 06 / 2026, p. 68 / 105 39 / 74 Inlet passage. The outlet end of the inlet passage of the cover / lid or flow chamber can be configured to seal the inlet passage of the insert or vice versa. For example, the outlet end of the inlet passage of the cover / lid or flow chamber can be configured to provide an interference fit with, around, or within the inlet end of the inlet passage of the insert or vice versa. Alternatively, the outlet end of the inlet passage of the cover / lid or flow chamber can be connectable to the inlet passage of the insert by a sealing element. The device may comprise a sealing element to seal the outlet end of the inlet passage of the cover / lid or flow chamber to the inlet passage of the insert when the cover / lid is connected to the drip chamber or when the insert is inserted into the flow chamber.The sealing element may be or comprise a sealing ring that may fit between the insert and the cover / lid or flow chamber. The cover / lid of the flow chamber may comprise the sealing element. For IV administration, the cover / lid may be or comprise a standard vented or non-vented piercing spike / device for insertion into or piercing of a liquid container, as is known in the art. The inlet passage. Petition 870260053140, dated 01 / 06 / 2026, page 69 / 105 40 / 74 of the cover / lid may extend through the spike / perforation device. Alternatively, where the drip chamber does not comprise a cover / lid, the drip chamber may comprise the spike or perforation device.

[0060] The cover or lid can be configured to close and seal the flow chamber opening by an interference fit. Alternatively or additionally, a sealing element that can fit between the drip chamber and the cover / lid, such as a sealing ring, can be used. The sealing element used to seal the inlet passage of the cover / lid to the inlet passage of the insert and the sealing element used to seal the cover / lid to the drip chamber can be an integral sealing element or separate sealing elements.

[0061] The device may further comprise one or more filter elements for filtering liquid upstream of the insert. The filter element(s) may be configured to fit between the insert and the cover / lid, and to cover at least the inlet end of the insert's inlet passage. The filter element(s) may also be configured to provide a seal between the insert's inlet passage and the cover / lid's inlet passage. The sealing element may comprise the Petition 870260053140, dated 01 / 06 / 2026, pp. 70 / 105 41 / 74 filter element(s) or vice versa. Where the insert comprises a filter element, a separate filter element may not be required. The cover / lid may be separate from the insert. Alternatively, the insert may comprise the cover / lid.

[0062] According to a third aspect of the invention, an IV administration assembly is provided comprising one or more inserts according to the first aspect. The assembly may comprise one or more flow measuring devices according to the second aspect. The assembly may further comprise one or more at least partially transparent drip chambers for receiving the insert. The drip chamber(s) may be standard drip chamber(s) for use in IV administration, as known in the art. The drip chamber(s) may comprise an outlet for receiving a flow of liquid from the insert outlet, for example, located downstream of the insert outlet. The assembly may further comprise one or more covers or lids for the drip chamber(s). The cover(s) / lid(s) may comprise a means for connecting the insert inlet passage to a liquid source.The cover(s) / cap(s) may comprise an inlet passage with an outlet end for connection to an insert inlet passage and an inlet end. Petition 870260053140, dated 01 / 06 / 2026, page 71 / 105 42 / 74 for connection to a liquid source. The cover(s) / cap(s) may or may not comprise a standard vented or non-vented spike for piercing a liquid source, such as a rigid IV bag or container, as is known in the art.

[0063] Alternatively, the drip chamber(s) may comprise a cover / lid. The drip chamber may comprise an inlet passage with an outlet end for connection to the insert's inlet passage and an inlet end for connection to a liquid source. The drip chamber may further comprise a means for connecting the insert's inlet passage to a liquid source, such as a spike or piercing device. The drip chamber may be a one-piece drip chamber, or a multi-piece drip chamber, for example, comprising an upper and a lower portion that are connectable to each other.

[0064] The assembly may also include tubing for connecting the outlet of the drip chamber(s) to an administration point. The assembly may also include one or more flow control devices. The flow control device(s) may be or include a fastening device for securing the tubing, such as a flow regulating valve or clamp valve. Petition 870260053140, dated 01 / 06 / 2026, page 72 / 105 43 / 74 compression as known in the art. Alternatively, the flow control device(s) may be for in-line connection to the tubing. The IV administration set may be used with or comprise other standard accessories known in the art, including, but not limited to, three-way stopcocks, injection ports, cannulas, Luer locks and / or locking clamps.

[0065] The outlet end of the cover(s) / lid(s) inlet passage may be connectable to the insert inlet passage by an interference fit. Alternatively, the outlet end of the cover(s) / lid(s) inlet passage may be connectable to the insert inlet passage by a sealing element.

[0066] The assembly may further comprise one or more filter elements for filtering a liquid flow upstream of the insert. The filter element(s) may be configured to fit between the insert and the cover(s) / cap(s) and cover at least the inlet end of the insert's inlet passage. Optionally or preferably, the sealing element may comprise the filter element.

[0067] According to a fourth aspect of the invention, a method of using an insert according to the first aspect is provided, a method of using a device of Petition 870260053140, dated 01 / 06 / 2026, page 73 / 105 44 / 74 flow measurement according to the second aspect, and / or a method of using the IV administration set according to the third aspect.

[0068] The method may comprise inserting an insert into an opening in a drip chamber or flow chamber. The method may further comprise attaching a cover or lid to the opening of the drip chamber or flow chamber to close and / or seal the drip / flow chamber. Attaching the cover / lid may further comprise positioning a filter element between the inlet end of the insert's inlet passage and the outlet end of the cover / lid's inlet passage. Attaching the cover / lid may further comprise connecting and / or sealing the inlet end of the insert's inlet passage with the outlet end of the cover / lid's inlet passage. The method may further comprise connecting the inlet end of the cover / lid's inlet passage to a liquid source.The step of connecting to a liquid source may involve piercing a liquid container with a spike or cap / lid piercing device. The method may further involve connecting the tubing to the drip / flow chamber outlet to direct the flow. Petition 870260053140, dated 01 / 06 / 2026, pp. 74 / 105 45 / 74 liquid to a point of use / administration. The method may further comprise the flow of a liquid through the flow measuring device. The method may further comprise reading a flow rate from the flow indicating channel.

[0069] The insertion step of the insert within the drip chamber or flow chamber may comprise inserting the insert to form the flow-resistant passage and / or the flow indication channel between the insert and a wall of the drip chamber or flow chamber. The insertion step may comprise inserting the insert to close and / or seal one or more recesses or open channels in the contact surface of the insert against a wall of the drip chamber or flow chamber.

[0070] The features described in the context of separate aspects and / or embodiments of the invention may be used together and / or may be interchangeable. Similarly, where features are, for brevity, described in the context of a single embodiment, these may also be provided separately or in any suitable subcombination. The features described in connection with the device may have corresponding features definable with respect to a method, and such embodiments are specifically provided. Petition 870260053140, dated 01 / 06 / 2026, pp. 75 / 105 46 / 74 BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order that the invention may be well understood, embodiments will now be discussed by way of example only with reference to the accompanying drawings, in which:

[0072] Figures 1a and 1b show, respectively, an exploded view and a perspective view of a flow measuring device according to the present invention;

[0073] Figure 2 shows a side view of the assembled flow measuring device of figure 1 with the insert visible;

[0074] Figures 3a and 3b show, respectively, an additional side view of the assembled flow measuring device of figure 1 with the insert visible and a cross-sectional view;

[0075] Figure 4a shows a detailed perspective view of the insert in figures 1 to 3;

[0076] Figure 4b shows a sketch of one or more recesses or open channels in the insert of figure 4a;

[0077] Figures 4c and 4d show, respectively, schematic horizontal and vertical cross-sections of the flow-resistant passage orifice of figure 4a;

[0078] Figures 4e and 4f show schematic vertical cross-sections of hole geometries. Petition 870260053140, dated 01 / 06 / 2026, page 76 / 105 47 / 7 4 alternatives;

[0079] Figures 5a and 5b show, respectively, additional perspective views of the insert from figures 1 to 4 from different angles indicating the paths of liquid flow;

[0080] Figure 6 shows an enlarged view of the insert in figures 1 to 5 indicating the liquid flow paths;

[0081] Figure 7 shows additional perspective views of the insert from figures 1 to 6 from a different angle showing an exit chamber;

[0082] Figures 8a and 8b show graduated scales for measuring a flow rate;

[0083] Figure 9 shows an additional perspective view of the insert from figures 1 to 7 indicating the direction of molding;

[0084] Figure 10 shows another exemplary insert for the device in Figure 1; and

[0085] Figure 11 shows another exemplary insert for the device in Figure 1.

[0086] It should be noted that the figures are diagrammatic and cannot be drawn to scale. The dimensions and relative proportions of parts of these figures may have been exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The Petition 870260053140, dated 01 / 06 / 2026, page 77 / 105 48 / 74 The same reference signs are generally used to refer to corresponding or similar features in modified and / or different modalities. DETAILED DESCRIPTION

[0087] Figures 1a-3b show a flow measuring device 100 according to one aspect and / or embodiment of the invention. The device 100 comprises a flow measuring insert 10, a flow chamber or housing 50 for receiving the insert 10, and a cover or lid 30 for closing / sealing the flow chamber 50 and connecting the device 100 to a liquid source (not shown). The device 100 is assembled by inserting the insert 10 into the flow chamber 50 and securing the cover or lid 30 to the flow chamber 50 to close and / or seal the flow chamber 50. The device 100 is configured to be disposed substantially and vertically in use, such that liquid can flow downwards through the device 100 under gravity. References to upper and lower below refer to this orientation, but it will be appreciated that aspects and embodiments of the invention are not limited to a particular orientation.

[0088] In the embodiment shown, the flow chamber 50 is a generally tubular member, comprising an opening, recess or hole 51 at an upper end for Petition 870260053140, dated 01 / 06 / 2026, pp. 78 / 105 49 / 74 accommodates the insert 10 and an outlet 52 at a lower end for connection to other components downstream of the device 100, such as piping and / or a flow control device (not shown). The opening, recess or hole 51 defines an interior volume or space of the chamber connected by a side wall 50w. It will be appreciated that the flow chamber 50 is not limited to the geometry shown, for example, the exterior of the wall 50w may have a regular or irregular shape and the interior volume of the drip chamber 50 may be substantially cylindrical as shown or non-cylindrical, provided that there is at least a portion that can accommodate and cooperate with the insert 10, as described below. The cover or lid 30 comprises an inlet passage 32 for receiving a liquid flow from a liquid source.In the example shown, the inlet passage 32 is formed into a projection or peak 31 for connecting the device 100 to a liquid source, for example, by inserting the peak 31 into an outlet of the liquid source, or by drilling the liquid source. However, it will be appreciated that other means for fluid connection of the device 100 to a liquid source may be used, such as plug fittings, threaded connections or Luer locks known in the art. When connected to a liquid source, the liquid enters the device 100 through the inlet passage 32. Petition 870260053140, dated 01 / 06 / 2026, pp. 79 / 105 50 / 74 of the cover / lid 30, flows through the insert 10 into the flow chamber 50 and exits the device 100 through the outlet 52. The insert 10 provides a direct visual indication of the liquid flow rate through the device 100, as further explained below. As such, at least a portion of the flow chamber 50 must be formed from or comprise a substantially or at least partially transparent material to allow at least a portion of the insert 10 to be visible through the side wall 50w of the flow chamber 50.

[0089] In the embodiment shown, the flow chamber 50 is a standard drip chamber and the cap / lid 30 is a standard vented or non-vented piercing spike / device used in intravenous (IV) administration sets, as is known in the art. The drip chamber 50 is constructed from a substantially transparent plastic material where at least a portion of the side wall 50w (i.e., the lower portion below the insert) is substantially flexible / deformable such that the flow of liquid in the drip chamber 50 can be observed and the IV set can be prepared in the usual manner by squeezing and releasing the flexible / deformable portion of the drip chamber to draw liquid from the liquid source and expel air upwards into the liquid source (e.g., a bag or Petition 870260053140, dated 01 / 06 / 2026, pages 80 / 105 51 / 74 IV container). The outlet end 32b of the inlet passage of the cover / lid 32 is configured to be compliant with ISO8536-4 (i.e., positioned 5 mm from the inner surface of the sidewall 50w), and typically comprises a drip-forming orifice as it is traditionally used to form drops to indicate the flow rate as visualized in the drip chamber 50. For example, the drip-forming orifice may be approximately 3 mm wide, or either narrower or wider, depending on the required drop size / volume. However, it will be appreciated that the present invention is not limited to IV administration and, as such, generally any suitable flow chamber 50 sized to accommodate the insert 10 (with a substantially transparent sidewall 50w), and any suitable cover / lid 30 with a means to connect the device 100 to a liquid source may be used, particularly in non-IV applications.

[0090] Figures 4a, 5a and 5b show the insert 10 in more detail. The insert 10 comprises an inlet passage 11, an outlet 13 and a flow-resistant passage 12 between the inlet passage and the outlet 13. This defines a primary liquid flow channel through the insert 10. The insert 10 also comprises a flow indication channel 14, whose lower end / inlet 14a is connected between Petition 870260053140, dated 01 / 06 / 2026, page 81 / 105 52 / 74 the inlet passage 11 and the flow-resistant passage 12. The attachment of the cover / cap 30 to the drip chamber 50 connects the inlet passage 32 to an inlet end 11a (upper end) of the inlet passage 11, as shown in figure 3b, thus providing a passage for liquid flow from a liquid source to the inlet passage 11 of the insert 10. An interference fit or separate sealing element may be used to provide a liquid-tight seal between the inlet passage 32 of the cover / cap 30 and the inlet passage 11 of the insert 10, as further discussed below.

[0091] The insert 10 has a length along a longitudinal geometric axis that is less than the length of the drip chamber 50. For IR administration, the drip chamber 50 may have a length at least 40 mm greater than the length of the insert 10, and the outlet 13 of the insert 10 may be positioned at least 5 mm from the (inner surface of) side wall 50w of the drip chamber 50, to meet ISO8536-4. However, it will be appreciated that for non-IR applications where compliance with ISO-8536-4 is not required, the insert 10 need only be equal to or shorter than the length of the drip chamber 50 to fit into it. In one example, the drip chamber 50 may have Petition 870260053140, dated 01 / 06 / 2026, p. 82 / 105 53 / 74 approximately 100 mm in length, and the insert 10 may be approximately 60 mm in length to conform to ISO-8536-4. Furthermore, the outlet 13 of the insert 10 may be or comprise a drip-forming orifice (e.g., with an opening approximately 3 mm wide), such that a flow of drops may still be visible in the drip chamber 50 as the liquid exits the insert 10, in accordance with ISO-8536-4 (which requires that drops be continuously visible in gravity-fed infusion equipment for medical use). In an insert approximately 60 mm long, the inlet passage 11 may be approximately 40 mm in length, which may encourage laminar flow.

[0092] In a standard 30 peak used in IV administration, the outlet end 32b is typically chamfered. The inlet end 11a of the inlet passage 11 may be shaped to accommodate this and provide an interference fit with the outlet end 32, to connect and seal the inlet passage 11 of the insert to the inlet passage 32 of the cover / cap 30. Alternatively, a separate sealing ring may be provided to seal the interface between the inlet passage 11 of the insert and the inlet passage 32 of the cover / cap 30 when the cover / cap 30 is attached (not shown). Petition 870260053140, dated 01 / 06 / 2026, page 83 / 105 54 / 74

[0093] The flow-resistant passage 12 comprises an inlet end 12a, an outlet end 12c, and a flow-restricted orifice 12b between the inlet end 12a and an outlet end 12c. An outlet end 11b (lower end) of the inlet passage 11 is in communication with the inlet end 12a of the flow-resistant passage 12. The lower end 11b of the inlet passage 11 is also in communication with the flow-indicating channel 14. In particular, the flow-indicating channel 14 comprises an inlet end (lower end) 14a in communication with the lower end 11b of the inlet passage 11 and the inlet end 12a of the flow-resistant passage 12, and generally extends upward from its lower end 14a to an open outlet end 14b (upper end), as shown in Figure 3a.The open upper end 14b of the flow-resistant channel 14 is in communication with the interior volume 51 of the drip chamber 50 (as well as the portion of the drip chamber 50 below the insert 10).

[0094] The flow-resistant passage 12 and the flow indication channel 14 are partially defined by one or more recesses or open channels 10r in a surface 10m, as can be seen in figures 4a, 5a and 5b. The sketch of the one or more recesses or open channels 10r is shown by Petition 870260053140, dated 01 / 06 / 2026, page 84 / 105 55 / 74 line in bold in figure 4b for clarity. The insert 10 is shaped and configured to have an interference fit within the drip chamber 50, such that the one or more recesses or open channels 10r are closed and sealed against the side wall 50w of the drip chamber 50 when the insert 10 is inserted into the drip chamber 50. The interference fit is provided by one or more contact surfaces 10m, 10m' that are configured to contact the inner surface of the side wall 50w when the insert 10 is inserted into the drip chamber 50. The one or more recesses or open channels 10r are formed on a contact surface 10m configured to contain, conform and seal against the inner surface of the side wall 50w when the insert 10 is inserted into the drip chamber 50.In this way, when the insert 10 is inserted into the dripping chamber 50, the flow-resistant passage 12 and the flow indication channel 14 are formed between the insert 10 and an inner surface of the side wall 50w. The contact surface 10m can be configured to at least partially deform the inner surface of the side wall 50w, and / or be at least partially deformed by the inner surface of the side wall 50w, to conform and make a liquid-tight seal between them. For example, where the insert 10 is formed of or. Petition 870260053140, dated 01 / 06 / 2026, pages 85 / 105 56 / 74 comprises a substantially rigid material, the side wall 50w of the drip chamber 50 may be substantially flexible or less rigid than the insert, such that the inner surface of the side wall 50w flexes or deforms at least partially to conform to the contact surface 10m of the insert 10 when the insert 10 is inserted into the drip chamber 50. Alternatively, where the insert 10 is formed of or comprises a substantially deformable material, the side wall 50w of the drip chamber 50 may be substantially rigid, such that the contact surface 10m deforms at least partially to conform to the inner surface of the side wall 50w. In both cases, the contact surface 10m is configured such that it can conform (after deformation or non-deformation) to the final inner surface of the side wall 50w when the insert 10 is inserted into the drip chamber 50.

[0095] The contact surface 10m may extend at least partially around the side(s) of the insert 10, and / or other contact surfaces 10m' may be provided at different locations around the side(s) of the insert 10 to encourage a tight fit with interference within the drip chamber 50. In the embodiment shown, other contact surfaces 10m' are provided in ribs or panels 16, 17 that extend into Petition 870260053140, dated 01 / 06 / 2026, page 86 / 105 57 / 74 direction ae / or between the side wall 50w, as seen in figures 5a, 5b and 7. The contact surface 10m in which the flow-resistant passage 12 and the flow indication channel 14 are partially defined is a continuous and substantially smooth surface to provide uniform sealing contact with the side wall 50w and prevent leaks. Alternatively or additionally, the contact surface 10m, 10m' may be or comprise one or more sealing ribs that reduce the contact area and encourage a liquid-tight seal against the inner surface of the side wall 50w of the drip chamber 50 (not shown). For example, the contact surface 10m may comprise one or more sealing ribs that extend around the (perimeter of) one or more recesses or open channels (not shown).The sealing ribs may have a substantially rounded or triangular profile and may be configured to deform the inner surface of the 50w side wall, or be deformed by the inner surface of the 50w side wall to make a liquid-tight seal between them.

[0096] The insert 10 may be formed of or comprise a substantially rigid material, such as acrylonitrile butadiene styrene (ABS) or any other material permitted for use in IV applications. In this case, the insert 10 may provide an interference fit within Petition 870260053140, dated 01 / 06 / 2026, page 87 / 105 58 / 74 of a substantially flexible / deformable portion of the drip chamber 50 to provide a liquid-tight seal between them. Alternatively, the insert 10 may be formed of or comprise a substantially flexible, deformable and / or compressible material, such as polyvinyl chloride (PVC) or any equivalent PVC-free plastic permitted for use in applications IV. In this case, the insert 10 may provide an interference fit within a substantially rigid portion of the drip chamber 50 to provide a liquid-tight seal between them.

[0097] In use, the liquid flow through the inlet passage 11 encounters the side wall 50w of the drip chamber 50 and is forced towards the flow-resistant passage 12. The flow resistance provided by the orifice 12b causes the liquid to enter the adjacent flow indication channel 14, as indicated by the arrows in Figures 5a and 5b. This liquid flow through the insert 10 is further illustrated by the arrows in Figure 6. The liquid level or height in the flow indication channel 14 will increase to a height proportional to the liquid flow rate through the flow-resistant passage 12 (explained further below), which can be regulated by an external flow control device (not shown). A scale 60 with calibrated indices 60i can Petition 870260053140, dated 01 / 06 / 2026, pages 88 / 105 59 / 74 may be placed in, next to, or near the flow indicator channel 14 to provide a clear reading of the liquid flow rate, as shown in Figure 8a. A visible float may also be provided in the flow indicator channel 14 to facilitate reading the liquid level / scale 60. The insert 10 or the drip chamber 50 may comprise the scale 60, as required.

[0098] The operating principle of device 100 is as follows: the flow-resistant liquid passage 12 provides resistance to liquid flow and an associated pressure drop according to the width of the orifice 12b and the liquid flow rate. When liquid flows through orifice 12b, its pressure builds up slightly upstream of orifice 12b before falling downstream of orifice 12b and eventually increasing again further downstream as the flow expands. The pressure P at the bottom of the liquid column in the flow indication channel 14 is given by P = pgh, where ρ is the density of the liquid, g is the gravitational constant, and eh is the height of the liquid. Thus, the flow resistance caused by orifice 12b causes the upstream liquid to recede, enter the flow indication channel 14, and reach a height h according to the pressure drop. The flow rate through orifice 12b is substantially the same as the flow rate in the rest of the Petition 870260053140, dated 01 / 06 / 2026, pages 89 / 105 60 / 74 primary liquid flow channel 12. The liquid flow rate through the device 100 can therefore be read directly from the liquid level / height in the flow indication channel 14 by means of the scale 60 (unless the flow rate is high enough to overflow the indication channel 14, as discussed below).

[0099] In one embodiment, the orifice 12b has a width between substantially 0.1 mm - 0.2 mm. This can provide adequate flow resistance to provide a discernible change in the liquid level / height in the flow indication channel 14 for flow rates in the range of approximately 0 - 250 ml / hour, covering a scale 60 of approximately 40 mm. However, it will be appreciated that other orifice widths can be used, depending on the application of the device 100 (e.g., the required scale size and / or the flow rates to be measured). The use of an orifice restriction (instead of an elongated restriction, such as a narrow tube / tube section) can make the flow measuring device 100 less susceptible to changes in liquid viscosity. As such, preferably, the orifice 12b is as close to having no length (in the direction of flow) as possible (within the constraints of the manufacturing process).As seen in figures 4a and 4b, orifice 12b is formed by a substantially V-shaped projection 10p extending to. Petition 870260053140, dated 01 / 06 / 2026, pp. 90 / 105 61 / 74 starting from a wall of the recess 10r or flow-resistant passage 12 that narrows the width of the passage. In the horizontal cross-section, the projection 10p extends from a floor of the recess 10r and opposes the wall 50w of the drip chamber 50, as shown in Figure 4c. Additionally, the projection 10p may extend, in the vertical cross-section, from a side wall of the recess 10r or flow-resistant passage 12 towards a substantially straight portion of an opposite side wall of the recess, as shown in Figures 4d. Alternatively, the narrowing of the orifice 12b may be formed by two opposing projections 10p in the vertical cross-section, as shown in Figure 4e. Ideally, the orifice 12b would be formed by one or more thin-walled projections 10p extending at least partially through the flow-resistant passage 12, as shown in Figure 4f.However, V-shaped projections 10p are a compromise between performance and manufacturability. The sharper the angle θν of the side walls forming the projection(s) 10p, the more ideal the orifice 12b becomes and the less susceptible the flow measuring device 100 is to changes in liquid viscosity (see figures 4c and 4d).

[00100] The flow-resistant liquid passage 12 is substantially U-shaped (when the insert 10 and the Petition 870260053140, dated 01 / 06 / 2026, pages 91 / 105 62 / 74 device 100 are arranged substantially vertically), such that the direction of liquid flow is substantially reversed as it passes through the flow-resistant liquid passage 12. The orifice 12b is located towards the bottom of the U-shaped flow-resistant liquid passage 12. The U-shaped flow-resistant liquid passage 12 provides that, when the liquid flow is interrupted by an operator, the liquid remains in the flow-resistant liquid passage 12. This prevents the orifice 12 from drying out, which can lead to an accumulation of solid deposits or crystals that can alter the size of the orifice 12b and adversely affect its function. For example, a reduction in the width of the orifice 12b would introduce error in the reading of the liquid flow in the flow indication channel 14, and eventual blockage of the orifice 12b would completely prevent liquid flow in the insert 10.

[00101] After passing through orifice 12b, the liquid flows substantially upwards to the outlet end 12c of the flow-resistant passage 12 and through an opening 15a into an outlet chamber 15, as shown in Figure 7. This flow through a submerged orifice 12b prevents droplets from forming during the restricted part of the flow. The purpose of the outlet chamber 15 is to direct liquid flow to the outlet 13, which is formed Petition 870260053140, dated 01 / 06 / 2026, pp. 92 / 105 63 / 74 on the floor of the outlet chamber 15. The opening 15a is positioned above the level / height of the outlet 13 when the insert 10 is arranged substantially and vertically such that the liquid flows downwards to the outlet 13. The outlet chamber 15 comprises a narrow channel 15b extending from the opening 15a to the floor of the outlet chamber 15. The narrow channel 15a draws liquid downwards into the outlet chamber by capillary action. As such, as the liquid flows from the opening 15a to the outlet 13, it is prevented from forming irregular droplets that could render the flow rate measurement unreliable. The narrow channel 15b can be a closed channel or an open channel. In the embodiment shown, the narrow channel 15b is an open channel. The open narrow channel 15b can be formed by a recess in a side wall of the outlet chamber 15 and thus can be easily formed by regular molding processes.The narrow open channel 15b is ideally semicircular in cross-section, with a width of less than 1 mm (approximately 0.5 mm).

[00102] The outlet chamber 15 comprises an overflow opening 15c communicating with the interior volume 51 of the drip chamber 50 (in particular, the portion of the drip chamber 50 below the insert 10). The overflow outlet 15c is positioned between the levels / heights of the outlet 13 and the opening 15a to prevent filling of Petition 870260053140, dated 01 / 06 / 2026, pages 93 / 105 64 / 74 liquid in the outlet chamber 15 which would otherwise introduce error in the flow rate measurement, particularly the “zero line” from the flow indication channel 14. In the embodiment shown, the overflow opening 15c is formed by a notch in the panel 16 and the outlet chamber 15 open to the interior volume 51 of the drip chamber 50, such that it does not close a gap. The open outlet chamber 15 and / or the overflow opening 15c allows air to flow between the outlet chamber 15 and the lower portion of the drip chamber 50. This prevents air blockages and allows the device 100 to be “prepared in the same way as existing drip assemblies, which involves squeezing and releasing the lower portion of the drip chamber 50 to draw liquid through the primary liquid passage from the liquid source and expel air upwards into the liquid source.

[00103] The insert 10 can be further shaped and configured to provide a gap G between the insert 10 and the side wall 50w of the drip chamber 50 by extending the length of the insert 10. The gap G can further assist air to flow between the outlet chamber 15 and the interior volume 51 of the drip chamber 50 (and thus 'priming', as discussed above). In the embodiment shown, the gap G is provided by the panel 16 which forms a chamfered side 16 of the Petition 870260053140, dated 01 / 06 / 2026, pages 94 / 105 65 / 74 insert 10, as seen in figure 7. The dashed line in figure 7 indicates the location of the side wall 50w when insert 10 is inserted into the drip chamber 50 and the resulting gap G formed between the side wall 50w and panel 16.

[00104] The inlet passage 11 may include a filter element (not shown) to filter the liquid before it reaches the flow-resistant passage 12 and to prevent any blockages by particulates contained in the liquid. The filter element may be provided at or near the upper end 11a of the inlet passage 11. The filter element may be integral with the insert 10. Alternatively or additionally, the device 100 may comprise a separate filter element that may be fitted between the insert 10 and the cover / lid 30 and / or between the drip chamber 50 and the cover / lid 30. Such a filter element may be integrated with a sealing ring (where present) to seal the interface between the inlet passage 32 of the cover / lid 30 and the inlet passage 11 of the insert 10 and / or the interface between the cover / lid 30 and the upper end of the drip chamber 50.For example, device 100 may comprise a flexible insert ring containing a filter element (not shown).

[00105] Figures 8a and 8b show scales Petition 870260053140, dated 01 / 06 / 2026, pages 95 / 105 66 / 74 examples 60, 62 which can be used to indicate a flow rate from the liquid level / height in the flow indication channel 14. A visible float (not shown) can also be provided in the flow indication channel 14 to improve the readability of the scale. In the embodiment shown in Figures 1 to 7, the flow indication channel 14 has a substantially constant horizontal cross-section, is substantially straight, and extends substantially vertically from its lower end 14a, when the insert 10 is arranged substantially vertically. In this case, a linear scale 60 with regularly spaced indices 60i can be used to indicate the flow rate from the liquid level / height, as shown in Figure 8a. However, it will be appreciated that it is not essential that the flow indication channel 14 be straight, vertical, and / or have a constant horizontal cross-section with liquid level / height.

[00106] In another embodiment (not shown), the flow indication channel 14 may extend upwards from its lower end 14a inclined Θ to the vertical (or the longitudinal geometric axis of the insert 10), for example, 0-45 degrees from the vertical, and a similar scale 60 may still be used. In this case, the flow indication channel 14 is also curved about the axis. Petition 870260053140, dated 01 / 06 / 2026, pages 96 / 105 67 / 7 4 geometric shape of the insert due to, after the curvature of the side wall 50w of the drip chamber 50. The slope of the flow indication channel 14 stretches the scale by a factor of 1 / cos(0), which may allow a more detailed scale to be used (i.e., with a greater number of indices 60i and / or smaller increments of the flow rate), thereby reducing the relative error in the flow rate reading. More accurate flow rate measurements are typically required at low flow rates (e.g., less than 50 ml / hour) where the relative error increases (as the measured value decreases). Low flow rates correspond to low liquid levels / heights.As such, in another embodiment (not shown), to increase measurement accuracy at low flow rates, the flow indication channel 14 comprises a lower portion extending upwards from its lower end 14a at an angle Θ to vertical (e.g., 0-45 degrees) and an upper portion extending substantially vertically from the lower portion. Figure 8b shows an exemplary angular scale 62 that can be used with such a flow indication channel 14. The scale 62 comprises an upper portion 62a with a first set of indices 62i and a lower portion 62b with a second set of indices 62i' that are different from the first set 62i. Petition 870260053140, dated 01 / 06 / 2026, pages 97 / 105 68 / 74

[00107] In another embodiment (not shown), the flow indication channel 14 may curve from the longitudinal geometric axis of the insert 10, for example, when viewed from the side of the insert 10. Tilting and / or curving the flow indication channel 14 with respect to the longitudinal geometric axis may allow the length of the insert to be reduced.

[00108] Alternatively or additionally, one or more notches or openings 14c may be formed in a wall of the flow indication channel 14, such that as the liquid level rises above the notch 14c, some liquid escapes (into the dripping chamber 50) through the notch 14c, as shown in Figure 10 where the arrows indicate the liquid flow in the flow indication channel 14. The presence of such a notch 14c means that much higher flow rates are required for the liquid level in the flow indication channel 14 to continue to rise above the notch 14c. Above the notch 14c, the liquid level is dependent on regular fluid mechanics due to flow resistance by the orifice 12b and also the loss of liquid from the flow indication channel 14 through the notch 14c. This provides a non-uniform or non-linear scale, with more flow sensitivity below the notch 14c, and less flow sensitivity above it.This feature of notch 14c can be repeated. Petition 870260053140, dated 01 / 06 / 2026, pages 98 / 105 69 / 74 as desired along the flow indication channel 14. A non-linear scale may be desirable in cases where greater accuracy of flow measurement is required at lower flow rates, but the same flow meter must also measure the high flow rates. A linear scale in such cases may be impractically large.

[00109] At high flow rates (e.g., greater than 250 ml / hour), the liquid may exceed the height of the flow indication channel 14 and flow out of the open top end 14b into the drip chamber 50 where it can exit the device 100 through the outlet 52. As such, the open top end 14b also serves as an overflow to allow the liquid to continue to flow freely through the device 100 under high flow conditions. For example, although a scale 60, 62 from 0-250 ml / hour may be provided for the flow indication channel 14 (as shown in figures 8a and 8b), a much higher flow rate, e.g., 3000 ml / hour or more, may still be achieved by the device 100 (the scale being unnecessary at such high flow rates).If flow control at rates higher than those measurable by the flow indication channel 14 is required, the drops exiting the drip formation orifice of the outlet 13 can be counted according to the counting methods of. Petition 870260053140, dated 01 / 06 / 2026, pages 99 / 105 70 / 74 known drop flow rate measurement in a drip chamber 50 (provided the flow rate is not so high that drops are no longer formed, see below). At very high flow rates (e.g., during resuscitations), the fluid flow exiting port 13 will form a steady stream rather than separate drops. This is consistent with regular IV drip sets (without insert 10), where the operator would expect a stream of flow from port 32b of peak 30 rather than drops to verify that free flow is occurring.

[00110] Figure 11 shows an embodiment of the insert 10 further comprising a vent channel 18. The vent channel 18 is a substantially vertical column running parallel to the flow indication channel 14 with a lower end 18a in fluid communication with the lower / outlet end 11b of the inlet passage 11 and an open upper end 18b, as shown. The vent channel 18 is configured to allow any bubbles in the liquid flow out of the inlet passage 11 to rise upwards in the vent channel 18, rather than entering the flow indication channel 14 which would adversely affect the flow rate measurement / reading. It will be appreciated that the liquid as well as any bubbles flow upwards in the vent channel 18. Petition 870260053140, dated 01 / 06 / 2026, pages 100 / 105 71 / 74 If there are no bubbles in the liquid flow exiting the inlet passage 11, the liquid would rise and fall to the same level in both the flow indication channel 14 and the vent channel 18. However, the vent channel 18 may also contain bubbles, and thus the liquid level in it should be ignored. Importantly, this means that the liquid level in the flow indication channel 14 is substantially free of bubbles and provides an accurate flow rate reading. The upper end 18b of the vent channel 18 is at least the same height as the upper end 14b of the flow indication channel 14 to prevent any excess / overflow of fluid (liquid and gas / bubbles) from the vent channel 18 from affecting liquid levels higher than the upper end 18b of the vent channel 18 in the flow indication channel 14.For example, if the upper end 18b of the vent channel 18 were below the upper end 14b of the flow indication channel 14, this would effectively act as a notch 14c, as described above, such that any liquid height in the flow indication channel 14 above the upper end 18b in this case would reflect the flow resistance through the orifice 12b (standard indication mechanism) and fluid losses outside end 18b, much like the notch 14c described above. Petition 870260053140, dated 01 / 06 / 2026, pages 101 / 105 72 / 74

[00111] The insert 10 can be formed by an injection molding process. In the embodiment shown, it is molded such that it can be molded using a one-way molding process, as indicated by the arrow in Figure 9 (i.e., such that a two-piece mold can be separated in a single direction). For example, the entry passage is formed at an angle to the longitudinal geometric axis, in the molding direction, such that the exit end 11b of the entry passage 11 extends to an outer surface of the insert and / or is in communication with one or more recesses or open channels 10r on the contact surface 10m of the insert. Furthermore, the exit 13 and the entry end 11a of the entry passage 11 are chamfered such that they can still be molded at an angle, and several surfaces of the insert 10 include a tilt angle for improved moldability.Insert 10 may also include several recessed surfaces, such as surface 10s shown in Figure 5a, to improve the release and separation of the molds from insert 10.

[00112] A one-way molding process can minimize the time and cost of the molding cycle. Additionally, since the flow-resistant liquid passage 12 is formed by an interference fit between the insert 10 and the side wall 50w of the chamber. Petition 870260053140, dated 01 / 06 / 2026, pages 102 / 105 73 / 74 drip 50, the critical geometry and dimensions of the flow-resistant liquid passage 12, particularly the orifice 12b, can be achieved with regular molding by injection techniques and tolerances.

[00113] Although insert 10 and device 100 are described above in the context of IV administration, they can also be used in series with other flow devices, such as electronic pumps and IV flow regulators, to monitor and / or adjust a flow rate.

[00114] From reading this revelation, other variations and modifications will become apparent to a person versed in the technique. Such variations and modifications may involve equivalent features and others that are already known in the technique and that, instead, may be used in addition to features already described here.

[00115] Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any new feature or any new combination of features disclosed herein, whether explicitly or implicitly, or any generalization thereof, whether or not referring to the same invention as currently claimed in any claim, and whether or not it mitigates any or all of the same technical problems as the present invention. Petition 870260053140, dated 01 / 06 / 2026, pp. 103 / 105 4 / 7 4

[00116] Features that are described in the context of separate modalities may also be provided in combination in a single modality. In contrast, several features that are, for brevity, described in the context of a single modality, may also be provided separately or in any suitable subcombination.

[00117] For the sake of completeness, it is also defined that the term comprising does not exclude other elements or steps, the term a or an does not exclude a plurality, and any reference signs in the claims should not be interpreted as limiting the scope of the claims. Petition 870260053140, dated 01 / 06 / 2026, pp. 104 / 105

Claims

1 / 10 CLAIMS 1. Flow measuring insert (10) for a drip chamber (50) suitable for use in intravenous administration, comprising: a primary liquid flow channel comprising: an inlet passage (11); an outlet (13); and a flow-resistant passage (12) between the inlet passage (11) and the outlet (13); and a flow indication channel (14) communicating with the primary liquid flow channel between the inlet passage (11) and the flow-resistant passage (12); characterized in that the flow-resistant passage (12) and the flow-indicating channel (14) is / are at least partially defined by one or more first recesses and / or open channels (10r) on a surface of the insert such that, when the insert (10) is inserted within said drip chamber (50), the flow-resistant passage (12) and the flow-indicating channel (14) are formed between the insert (10) and a wall of said drip chamber;and wherein the flow-resistant passage (12) provides resistance to a flow of liquid through the primary liquid flow channel such that the liquid is forced into the flow indication channel (14) and reaches a level or Petition 870260053140, dated 01 / 06 / 2026, page 10 / 105 2 / 10 height in the flow indication channel (14) proportional to the rate of liquid flow through the primary liquid flow channel.; 2. Insert, according to claim 1, characterized in that one surface is a contact surface (10m) of the insert configured to fit, contact and / or seal against the wall of said drip chamber (50) when the insert is inserted into said drip chamber (50).

3. Insert, according to claim 2, characterized in that the contact surface (10m) is configured to conform to the inner surface of the drip chamber (50) when the insert (10) is inserted into the drip chamber (50), and / or comprising one or more sealing ribs (16, 17) extending around one or more recesses or open channels (10r) to seal against the inner surface of the drip chamber wall (50) when the insert is inserted into the drip chamber (50).

4. Insert (10), according to any of the preceding claims, characterized in that the flow-resistant passage (12) is U-shaped when the insert (10) is arranged vertically, such that, when inserted within said dripping chamber (50) and arranged vertically, the liquid remains in the flow-resistant passage (12) when a liquid flow is interrupted.

5. Insert (10), according to any of the preceding claims, characterized in that the flow-resistant passage (12) comprises an orifice (12b); and optionally or preferably, when dependent on claim 3, wherein the orifice is located in or near a lower portion of the U-shaped flow-resistant passage (12) when the insert (10) is arranged vertically.

6. Insert (10), according to any of the preceding claims, characterized in that it further comprises an outlet chamber (15) communicating with an outlet end of the flow-resistant passage (12) and the outlet (13) for directing a flow of liquid from the flow-resistant passage (12) to the outlet (13).

7. Insert (10), according to claim 6, characterized in that the outlet chamber (15) comprises a second channel (15b) extending from the outlet end of the flow-resistant passage (12) configured to direct a flow of liquid from the flow-resistant passage (12) to the outlet (13) without forming droplets; and optionally or preferably, wherein the second channel (15b) is or comprises a second open channel formed at least partially in a side wall of the outlet chamber (15) and extending to a floor of the outlet chamber (15).

8. Insert, according to claim 7, characterized in that the second channel is configured to draw liquid into the outlet chamber by capillary action.

9. Insert (10), according to any one of claims 6 to 8, characterized in that the outlet chamber (15) comprises the outlet (13) and in that the outlet end of the flow-resistant passage (12) is positioned at a level or height above a level or height of the outlet (13) when the insert (10) is arranged vertically; and optionally or preferably, in that the outlet (13) is located on a floor of the outlet chamber (15).

10. Insert (10), according to claim 9, characterized in that the outlet chamber (15) further comprises an overflow outlet (15c) positioned at a level or height between the level or height of the outlet (13) and the level or height of the outlet end of the flow-resistant passage (12).

11. Insert (10), according to any of the preceding claims, characterized in that the flow indication channel (14) comprises a graduated scale (60, 62) to provide a visual measure of the level or height of liquid in the flow indication channel (14) and, in this way, the rate of flow of liquid through the primary liquid flow channel; and, optionally or preferably, comprises a visible float to facilitate reading of the liquid level.

12. Insert (10), according to any of the preceding claims, characterized in that the flow indication channel (14) comprises: an inlet end communicating with an outlet end of the inlet passage (11) and an inlet end of the flow-resistant passage (12), and the flow indication channel (14) extends upward from its inlet end when the insert is arranged vertically; and optionally or preferably, an open outlet end to allow an overflow; and / or a notch or opening (14c) in a wall of the flow indication channel (14) at a position above the configured inlet end to allow a flow of liquid out of the flow indication channel (14).

13. Insert (10), according to claim 12, when dependent on claim 11, characterized in that at least a portion of the flow indication channel (14) extends from its inlet end at an angle to the vertical when the insert is arranged vertically to increase the graduation spacing on the scale (60, 62); and optionally or preferably, wherein the flow indication channel (14) is curved around a longitudinal and / or transverse axis of the insert.

14. Insert (10), according to any of the preceding claims, characterized in that the outlet (13) comprises a drip-forming orifice.

15. Insert (10), according to any of the preceding claims, characterized in that it further comprises: a vent channel (18) communicating with and extending upward from an outlet end of the inlet passage (11) configured for venting bubbles in a liquid flow exiting the inlet passage (11) before entering the flow indication channel (14); and / or one or more filter elements located at or near the inlet end of the inlet passage (11).

16. Insert (10), according to any of the preceding claims, characterized in that it is molded and / or configured to provide an interference fit within said drip chamber (50); and optionally or preferably, when dependent on claim 3, wherein the seal between the contact surface (10m) and the inner surface of the wall of said drip chamber (50) is provided by the interference fit.

17. Insert (10), according to claim 16, characterized in that it comprises one or more ribs or projections (17) extending away from the insert (10) and configured to contact a wall of said drip chamber (50) when the insert (10) is inserted into said drip chamber (50) to provide interference fit.

18. Insert (10), according to any of the preceding claims, characterized in that the insert (10) is formed of or comprises a rigid or deformable material; and, optionally or preferably, wherein the insert (10) is or comprises a one-piece mold formed by an injection molding process, optionally or preferably, by a one-way injection molding process.

19. Flow measuring device, characterized in that it comprises the insert (10), as defined in any of the preceding claims, and a flow chamber (50) for receiving the insert (10), the flow chamber (50) comprising: an opening through which the insert (10) may be inserted; Petition 870260053140, dated 01 / 06 / 2026, page 16 / 105 8 / 10 an outlet (52) for receiving a liquid flow from the outlet (13) of the insert (10); and one or more walls, at least one of the one or more walls including a transparent portion for viewing the liquid level in the flow indication channel (14).

20. Device according to claim 19, characterized in that it further comprises a cover or lid (30) connectable to the opening of the flow chamber (50), wherein the cover or lid (30) comprises an inlet passage (11) with an outlet end for connection to the inlet passage (11) of the insert (10) and an inlet end for connection to a liquid source; or wherein the flow chamber comprises an inlet passage (11) with an outlet end for connection to the inlet passage (11) of the insert and an inlet end for connection to a liquid source.

21. Device according to claim 20, characterized in that the outlet end of the inlet passage (32) of the cover / lid (30) or flow chamber (50) is connectable to the inlet passage (11) of the insert (10) by an interference fit; or wherein the outlet end of the inlet passage (11) of the cover / lid (30) or flow chamber (50) is connectable to the inlet passage (11) of the insert (10) by a sealing element; and optionally or preferably, wherein the sealing element comprises a filter element for filtering a liquid flow upstream of the insert (10).

22. Device according to claim 19, 20 or 21, characterized in that the flow chamber (50) is or comprises a drip chamber that is at least partially transparent for use in intravenous administration.

23. Intravenous administration set, characterized in that it comprises: an insert (10), as defined in any one of claims 1 to 18; a drip chamber (50) at least partially transparent for receiving the insert (10), the drip chamber (50) comprising an outlet (52) for receiving a flow of liquid from the outlet (13) of the insert (10); tubing for connecting the outlet (52) of the drip chamber (50) to an administration point; and a flow control device.

24. Intravenous administration set, according to claim 23, characterized in that it further comprises a cover or lid (30) for the drip chamber (50), the cover or lid (30) comprising an inlet passage (11) with an outlet end for connection to the inlet passage (11) of the insert (10) and an inlet end for connection to a liquid source, or wherein the drip chamber (50) comprises an inlet passage (32) with an outlet end for connection to the inlet passage (11) of the insert (10) and an inlet end for connection to a liquid source;and, optionally or preferably: wherein the outlet end of the inlet passage (32) of the cover / lid (30) or drip chamber (50) is connectable to the inlet passage (11) of the insert (10) by an interference fit and, optionally or preferably, wherein the insert (10) comprises a filter element located at or near the inlet end of the inlet passage (11) of the insert (10); or wherein the outlet end of the inlet passage (32) of the cover / lid (30) or drip chamber (50) is connectable to the inlet passage (11) of the insert (10) by a sealing element; and, optionally or preferably, wherein the sealing element comprises a filter element for filtering a liquid flow upstream of the insert (10). Petition 870260053140, dated 01 / 06 / 2026, page 19 / 105;

Images