Tubes for transporting fluids

Abstract

An aspect of the invention relates to a tube for transporting a fluid, the tube comprising a first passageway, a second passageway with a pressure sensor connection point penetrating a wall of the second passageway, and a valve configured to be open when fluid flow through the tube is in a first direction and closed when fluid flow through the tube is in a second direction opposite the first direction, the pressure sensor connection point being upstream of the valve when fluid flow is in the first direction and downstream of the valve when fluid flow is in the second direction, wherein when the valve is open fluid can be transported through the first passageway and when the valve is closed fluid cannot be transported through the first passageway.

Description

[Technical field]

[0001] The present disclosure relates to a tube for transporting a fluid, particularly but not exclusively to a tube for transporting a fluid in an obstructive sleep apnea screening device, and to an obstructive sleep apnea screening device.

[0002] Aspects of the invention relate to tubes and devices. [Background technology]

[0003] Sleep apnea is a condition that causes a patient to temporarily stop breathing while sleeping. If left untreated, it can lead to a number of conditions, from chronic fatigue to cardiovascular problems.

[0004] It is known to provide screening devices for ascertaining breathing during sleep, such devices measuring airflow through a nasal cannula connected to a pressure sensor.

[0005] It is an object of the present invention to address one or more of the disadvantages associated with the prior art. Summary of the Invention

[0006] Aspects and embodiments of the present invention provide tubes and devices as claimed in the accompanying claims.

[0007] According to one aspect of the invention, there is provided a tube for transporting a fluid comprising a first passageway, a second passageway having a pressure sensor connection point penetrating a wall of the second passageway, and a valve configured to be open when fluid flow through the tube is in a first direction and configured to be closed when fluid flow through the tube is in a second direction opposite the first direction, the pressure sensor connection point being upstream of the valve when fluid flow is in the first direction and downstream of the valve when fluid flow is in the second direction, wherein when the valve is in the open state, fluid can be transported through the first passageway and when the valve is in the closed state, fluid cannot be transported through the first passageway.

[0008] An advantage of this aspect of the invention is that the pressure detected when the fluid is flowing in the first direction will be different than when the fluid is flowing in the second direction because there is a greater fluid flow through the pressure sensor when the fluid is flowing in the second direction, and therefore the direction of fluid flow can be more easily determined.

[0009] When the valve is open, fluid may be conveyed through the first passageway and the second passageway, and when the valve is closed, fluid may be conveyed only through the second passageway. This provides the advantage of modifying the fluid flow acting in the second direction when the valve is closed in the second direction, thereby directing the fluid to flow only through the second passageway. Thus, the relative pressure difference in the two-way flow may be passively amplified by this aspect of the invention.

[0010] The tube may include a pressure sensor attached to the pressure sensor connection point for measurement of the pressure of the fluid flow through the second passage of the tube.

[0011] The pressure sensor may have a pressure sensing element within the fluid flow inside the second passageway.

[0012] The pressure sensor connection point may be a pressure sensor tap. The pressure sensor tap may be connected to a pressure sensing element outside the second passageway.

[0013] The tube may be circular in cross section.

[0014] The first passage may be annular in cross-section and have a first outer diameter and the second passage may be circular in cross-section and have a second outer diameter. The second passage may be concentric with the first passage. The second outer diameter may be smaller than the first outer diameter. The valve may be annular in cross-section and have an outer valve diameter in the closed state substantially equal to the first outer diameter and an inner valve diameter in the closed state substantially equal to the second outer diameter.

[0015] The first passage may be a first segment of the tube forming, in cross-section, a first portion of the tube, the second passage may be a second segment of the tube forming, in cross-section, a second portion of the tube, and the valve may be a segment that, in cross-section when in a closed state, encompasses substantially the same cross-section as the first passage.

[0016] The first segment may be a semicircle whose cross-section forms a first half of the tube, and the second segment may be a semicircle whose cross-section forms a second half of the tube.

[0017] The second passage may include an expansion chamber, which provides the advantage of further modifying the pressure differential between the fluid flow in the first direction and the fluid flow in the second direction.

[0018] The second passageway may include a throttle plate such that the pressure sensor connection point is between the throttle plate and the valve.

[0019] The throttle plate may include drainage holes for draining liquid condensate from the tubes.

[0020] According to one aspect of the invention, there is provided a device comprising a tube according to any of the preceding aspects and a pressure sensor according to the preceding embodiments, further comprising a processor for receiving a signal from the pressure sensor, a memory and a power source.

[0021] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives, particularly their individual features, described in the preceding paragraphs, claims, and / or in the following description and drawings, can be used independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any manner and / or combination, unless such features are inconsistent. The applicant reserves the right to modify any originally filed claim or to file any new claim accordingly, including the right to amend any originally filed claim to depend on any other claim and / or to incorporate any feature thereof, even if not originally so claimed.

[0022] One or more embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings. [Brief description of the drawings]

[0023] [Figure 1] 1 shows a cross-sectional view of a tube according to one embodiment of the present invention with an open valve. [Diagram 2] 2 shows a cross-sectional view of the tube of FIG. 1 with a closed valve. [Diagram 3] 3 shows a cross-sectional view of the tube of FIG. 1 and FIG. 2 at section X1-X2. [Figure 4] 3 shows a cross-sectional view of the tube valve portion taken along the line Y1-Y2 of FIG. 2. [Diagram 5] 1 shows a cross-sectional view of a tube according to one embodiment of the present invention with an open valve. [Figure 6] 6 shows a cross-sectional view of the tube of FIG. 5 with a closed valve. [Figure 7]5 and 6. FIG. 6 shows a cross-sectional view of the tube taken along the line X3-X4. [Figure 8] 7 shows a cross-sectional view of the valve portion of the tube taken along the line Y3-Y4 of FIG. 6. [Figure 9] 1 shows a cross-sectional view of a tube according to one embodiment of the present invention with an open valve. [Figure 10] 1 shows a cross-sectional view of a tube according to one embodiment of the present invention with an open valve. [Figure 11] 1 shows a cross-sectional view of a tube according to one embodiment of the present invention with an open valve. [Figure 12] 12 shows a cross-sectional view of the tube at the throttle plate portion taken along the cross section X5-X6 of the tube in FIG. 11. [Figure 13] 1 shows a cross-sectional view of a tube according to one embodiment of the present invention with an open valve. [Figure 14] 14 shows a cross-sectional view of the tube of FIG. 13 at section X7-X8. [Figure 15] 1 illustrates a device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In the drawings, like elements are represented by like reference numerals.

[0025] The examples of the present disclosure relate to tubes. In particular, the examples of the present disclosure relate to dual-passage tubes, although it should be understood that a variety of numbers of passages may be provided. Non-limiting examples will now be described with reference to the accompanying Figures 1-15, which show tubes 10, 110, 210, 310, 410, 510, and device 100.

[0026] The tube 10, 110, 210, 310, 410, 510 of the present invention is intended for use in an obstructive sleep apnea device 100, which includes the tube 10, 110, 210, 310, 410, 510, memory 104, power source 106, processor 108, and either a sensor 102 disposed on the outside of the tube 10, 110, 210 or a sensor 316 disposed on the inside of the tube 310, 410, 510. The obstructive sleep apnea device 100 may provide the functionality of a screening device for measuring parameters associated with sleep apnea. The device may amplify the flow pressure difference between the forward and reverse flow directions without the need for active amplification.

[0027] Referring to FIG. 1, a tube 10 is shown having two passages 12, 14 that function as fluid channels, each passage 12, 14 capable of transporting a fluid, such as a gas or liquid, between two points in a fluid transfer system.

[0028] The tube 10 includes a first passageway 12 and a second passageway 14. The second passageway 14 has a pressure sensor connection point 16 that penetrates a wall 18 of the second passageway 14. The pressure sensor connection point 16 may be a pressure sensor tap. The pressure sensor tap may be connected to a pressure sensing element 102 outside the second passageway 14.

[0029] Tube 10 includes a valve 20 that is configured to be open, as shown in Figure 1, when fluid flow through tube 10 is in a first direction 22, and to be closed, as shown in Figure 2, when fluid flow through tube 10 is in a second direction 24 opposite the first direction 22. In Figures 1 and 2, first direction 22 is from left to right and second direction 24 is from right to left.

[0030] The pressure sensor node 16 is upstream of the valve 20 when the fluid flow is in a first direction 22. The pressure sensor node 16 is downstream of the valve 20 when the fluid flow is in a second direction 24.

[0031] The valve 20 has movable parts that are actuated between an open state and a closed state due to the force exerted by the flow of fluid on the valve 20. When fluid flows in a first direction 22, the valve 20 is acted upon by the fluid to be forced open as shown in Figure 1, resulting in fluid flow through both the first passageway 12 and the second passageway 14. When fluid flows in a second direction 24, the valve 20 is acted upon by the fluid to be forced closed as shown in Figure 2, resulting in the valve 20 closing the opening 26 of the first passageway 12 and preventing fluid from passing therethrough, so that fluid can only flow through the second passageway 14.

[0032] In the present example, when the valve 20 is in an open state, fluid may be transported through the first passageway 12, and when the valve 20 is in a closed state, fluid may not be transported through the first passageway 12. In various embodiments, the tube may include multiple passageways, one or more of which may be prevented from transporting fluid when the valve 20 is in a closed state, while one or more of the passageways may allow the passage of fluid when the valve 20 is in a closed state.

[0033] In the example of Figures 1 and 2, when the valve 20 is in an open state, fluid can be transported through both the first passageway 12 and the second passageway 14, and when the valve 20 is in a closed state, fluid cannot be transported through the first passageway 12, but can only be transported through the second passageway 14. When considering a fluid transport system in which the same volume of fluid must pass through the tube in the first direction 22 and the second direction 24, for example in a sleep apnea screening device in which the user breathes through a mask connected to the tube 10, closing the valve 20 to prevent fluid from passing through the first passageway 12 when the fluid flow through the tube 10 is in the second direction 24 means that all of the fluid will pass through the second passageway 14 in the second direction 24. In such a scenario, a different fluid pressure exists at the pressure sensor connection point 16 while the fluid is flowing in the first direction 22 than while the fluid is flowing in the second direction 24, providing an indication of the direction of fluid flow and making it easier to detect the direction of fluid flow using only a single sensor.

[0034] Figure 3 shows a cross-sectional view of tube 10 through section X1-X2 of Figure 1. In this example, the cross-section of tube 10 is circular, or annular, providing a circular interior channel. In this example, first passage 12 is annular in cross-section, i.e., first passage 12 is annular section 28 of tube 10, and second passage 14 is circular in cross-section, i.e., second passage 14 is circular section 30 of tube 10.

[0035] The first passageway 12, which is annular, has an outer diameter and an inner diameter. The second passageway 14, which is circular, has an outer diameter that substantially matches the inner diameter of the first passageway 12. In FIG. 3, the second passageway 14 is concentric with the first passageway 12, but this may not be the case in some embodiments. The outer diameter of the first passageway 12 is smaller than the outer diameter of the second passageway 14. The cross-section of the tube 10 may be consistent along the length of the tube 10 through which the first passageway 12 and the second passageway 14 exist, i.e., the outer diameter of the first passageway 12 and the outer diameter of the second passageway 14 may remain constant along such length of the tube 10.

[0036] Figure 4 shows a cross-sectional view of the tube 10 through section Y1-Y2 of Figure 2. In this example, the valve 20 is in a closed position, the valve 20 is annular in cross-section. The valve 20, which may be made of a flexible material in order to move from the open state shown in Figure 1 to the closed state shown in Figure 2, has an outer diameter in the closed state substantially equal to the first outer diameter of the first passage 12 and a second outer diameter, i.e. an inner diameter in the closed state substantially equal to the outer diameter of the second passage 14. Thereby, when the valve 20 is in the closed state, the first passage 12 is completely blocked from the fluid path, so that the fluid conveyed in the second direction 24 can only pass through the second passage 14.

[0037] Alternative embodiments are shown in FIGS.

[0038] Referring to FIG. 5, a tube 110 is shown having two passages 112, 114 that function as fluid channels, each passage 112, 114 capable of transporting a fluid, such as a gas or liquid, between two points in a fluid transfer system.

[0039] The tube 110 includes a first passageway 112 and a second passageway 114. The second passageway 114 has a pressure sensor connection point 116 that passes through a wall 118 of the second passageway 114.

[0040] Tube 110 includes a valve 120 that is configured to be open when fluid flow through tube 110 is in a first direction 122, as shown in Figure 5, and to be closed when fluid flow through tube 110 is in a second direction 124 opposite to first direction 122, as shown in Figure 6. In Figures 5 and 6, first direction 122 is from left to right and second direction 124 is from right to left.

[0041] The pressure sensor node 116 is upstream of the valve 120 when the fluid flow is in a first direction 122. The pressure sensor node 116 is downstream of the valve 120 when the fluid flow is in a second direction 124.

[0042] The valve 120 comprises a movable part that operates between an open state and a closed state due to the force exerted by the flow of fluid on the valve 120. When the fluid flows in a first direction 122, the valve 120 is forced open by the action of the fluid as shown in Figure 5, resulting in the fluid flowing through both the first passageway 112 and the second passageway 114. When the fluid flows in a second direction 124, the valve 120 is forced closed by the action of the fluid as shown in Figure 6, resulting in the valve 120 closing the opening 126 of the first passageway 112 and preventing the fluid from passing therethrough, so that the fluid can only flow through the second passageway 114.

[0043] In the present example, when valve 120 is in an open state, fluid may be transported through first passageway 112, and when valve 120 is in a closed state, fluid may not be transported through first passageway 112. The tube may comprise multiple passageways, one or more of which are prevented from transporting fluid when valve 120 is in a closed state, while one or more of the passageways may allow the passage of fluid when valve 120 is in a closed state.

[0044] 5 and 6, when the valve 120 is in an open state, fluid can be transported through both the first passageway 112 and the second passageway 114, and when the valve 120 is in a closed state, fluid cannot be transported through the first passageway 112, but can only be transported through the second passageway 114. When considering a fluid transport system in which the same volume of fluid must pass through the tube 110 in the first direction 122 and the second direction 124, for example in a sleep apnea screening device where the user breathes through a mask connected to the tube 110, closing the valve 120 to prevent fluid from passing through the first passageway 112 means that all fluid passes through the second passageway 114 when the fluid flow through the tube 110 is in the second direction 124. In such a scenario, different fluid pressures exist at the pressure sensor connection point 116 while the fluid is flowing in the first direction 122 compared to while the fluid is flowing in the second direction 124, providing an indication of the direction of fluid flow and making it easier to detect the direction of fluid flow using only a single sensor.

[0045] Figure 7 shows a cross-sectional view of the tube 10 through section X3-X4 of Figure 5. In this example, the cross-section of the tube 110 is circular, or annular, providing a circular interior channel. However, rather than having concentric passages 12, 14 for the transport of fluid as shown in Figure 1, the first passage 112 may be a first segment 128 of the tube 110 forming a first portion of the tube 110 in cross-section, and the second passage 114 may be a second segment 130 of the tube 110 forming a second portion of the tube 110 in cross-section.

[0046] Figure 8 shows a cross-sectional view of the tube 110 through section Y3-Y4 of Figure 6. In this example, the valve 120 is in a closed position, the valve 120 is arcuate in cross-section. The valve 120, which may be formed of a flexible material to transition from the open state shown in Figure 5 to the closed state of Figure 6, has a cross-section that encompasses substantially the same cross-section as the first passageway 112. Thereby, when the valve 120 is in the closed state, the first passageway 112 is completely blocked from the fluid path, so that fluid conveyed in the second direction 124 can only pass through the second passageway 114.

[0047] Thus, there is a chord of the tube 110 between the passages 112 and 114. In the embodiment shown in Figure 5, the chord is the diameter of the tube 110, but in other embodiments, the chord need not be the diameter of the tube 110. In the embodiment shown in Figure 7, the first segment 128 is a semicircle whose cross section forms a first half of the tube 110, and the second segment 130 is a semicircle whose cross section forms a second half of the tube 110. In Figure 8, the bulb 120 is shown to be a semicircle of substantially the same dimensions as the first segment 128.

[0048] Figure 9 shows a modification of the previously described embodiments in which the second passageway 14, 114 may be provided with an expansion chamber. Although shown in Figure 9 in relation to the embodiment of Figure 1, it will be appreciated that the expansion chamber features are also applicable to the embodiment of Figure 5.

[0049] Figure 9 modifies the example of Figure 1 by modifying the wall 18 of the second passageway 14 having the pressure sensor connection point 216 to be an expanded wall 218, providing a widened portion of the second passageway 14 and a narrowed section of the first passageway 12 to produce a tube 210 with an expansion chamber 214 and a flow restriction section 212. The effect of the expansion chamber 214 is to change the fluid pressure observed at the pressure sensor connection point 216 while the fluid is flowing in the first direction 22 and while the fluid is flowing in the second direction 24.

[0050] FIG. 10 illustrates another modification that may be provided in the tube 310. Although illustrated in relation to the embodiment of FIG. 9, it will be understood that the modification illustrated in FIG. 10 may be applied to any other embodiment of the present disclosure. While FIGS. 1-9 illustrate a pressure sensor connection point 16, 116, 216 in the form of a tap or tap point (to which a further tube or pipe may be connected to facilitate connection to the sensor 102, as shown in FIG. 15), FIG. 10 illustrates a pressure sensor 316 disposed in the fluid flow in the second passage 14, 114, or expansion chamber 214. That is, the tube 310 may include a pressure sensor 316 attached to the pressure sensor connection point 216 for measurement of the pressure of the fluid flow through the second passage 14, 114, or expansion chamber 214 of the tube 310. The pressure sensor 316 may be any device that converts a magnitude of physical pressure exerted on a sensing element of the pressure sensor 316 into an output signal that can be used to establish a quantitative value of the pressure in the passage 14, 114, or expansion chamber 214.

[0051] Figure 11 illustrates another modification that may be provided in tube 410. Although illustrated with respect to the embodiment of Figure 10, it will be understood that the modification illustrated in Figure 11 may be applied to any other embodiment of the present disclosure.

[0052] 11 , the second passageway 214 is provided with a throttle plate 402 upstream of the pressure sensor 316 in the fluid flow in the first direction 422. Fluid flow in a second direction 424 opposite the first direction 422 can present fluid to the pressure sensor 316, but the throttle plate 402 throttles the passage of fluid conveyed further downstream of the throttle plate 402 in the second direction 424 of fluid flow. Fluid flow can only pass through the throttle plate 402 via throttle openings 404 in the throttle plate 402. Thus, the second passageway 214 may include the throttle plate 402, and as a result, the pressure sensor connection point 216 is between the throttle plate 402 and the valve 20.

[0053] FIG. 12 shows a cross-sectional view of the tube 410 through section X5-X6 of FIG. 11. In this example, the cross-section of the tube 410 is circular or annular providing a circular interior channel. In this example, the first passage 212 is annular in cross-section, i.e., the first passage 212 is an annular section of the tube 410. Inside the first passage 212 is a throttle plate 402, which throttles the second passage 214 of the tube 410. The throttle plate 402 may be annular or substantially annular in cross-section, the throttle opening 404 defines a central portion of the throttle plate 402, and the throttle opening 404 is circular or substantially circular in cross-section. The throttle opening 404 may be elliptical or another shape in cross-section. The combination of the throttle plate 402 and the throttle opening 404 defines a circular section in the tube 410. Fluid flow in a second direction 424 opposite to the first direction 422 can present fluid to the pressure sensor 316, but the throttle plate 402 having the throttle opening 404 throttles the passage of fluid transported further downstream of the throttle plate 402 in the second direction 424 of fluid flow, thereby altering the pressure in the second passage 214.

[0054] 13 shows a modification of the embodiment of FIGS. 11 and 12 in which the throttle plate 502 is neither circular nor annular in cross section. The throttle plate 502 may have small throttle openings 504 therethrough, which may be moisture drain holes 504 in embodiments in which the fluid is a gas. The drain holes 504 may be suitable for draining liquid condensate from the tubes 510. Fluid flow in a second direction 424 opposite the first direction 422 may present fluid to the pressure sensor 316, but the throttle plate 502 with the drain holes 504 may throttle the passage of fluid conveyed further downstream of the throttle plate 502 in the second direction 424 of fluid flow, thereby altering the pressure in the second passage 214.

[0055] FIG. 14 shows a cross-sectional view of the tube 510 through section X7-X8 of FIG. 13. In this example, the cross-section of the tube 510 is circular, or annular, providing a circular internal channel. In this example, the first passage 212 is annular in cross-section, i.e., the first passage 212 is an annular section of the tube 510. Inside the first passage 212 is a throttle plate 502 having drain holes 504. The throttle plate 402 forms a larger segment of the circle defined by the internal channel of the tube 510, and the drain holes 504 form a smaller segment of the circle defined by the internal channel of the tube 510. The boundary between the throttle plate 502 and the drain holes 504 is shown as a chord, although any other shape of drain holes 504 may be provided. However, the placement of the drain holes 504 in the wall 218 of the second passage 214 allows for optimal fluid drainage.

[0056] FIG. 15 shows a device 100 with a tube 10, 110, 210, 310, 410, 510 according to any of the previously described embodiments, shown as tube 10 in the configuration shown in FIG. 1, without details of valve 20, expansion chamber 214, throttle plate 402, 502, throttle opening 404 and drain hole 504 for simplicity. The device may be an obstructive sleep apnea device 100 with a tube 10, 110, 210, 310, 410, 510. The device 100 further comprises a processor 108 for receiving signals from the sensor, a memory 104 and a power source 106. In embodiments where the sensor 316 is not provided in the fluid flow in the tube 10, 110, 210, the sensor 102 may be provided in the device 100 outside the tube 10, 110, 210. In embodiments where the sensor 316 is provided in the fluid flow in the tube 310, 410, 510, an additional sensor 102 may not be required.

[0057] Although the above embodiments are described in relation to tubes, they may equally be applied to pipes or any other fluid transport device. The cross-section of a tube, pipe or other fluid transport device may be of any shape, such as circular, square, rectangular, oval or any other shape. The above embodiments may also describe a container used as part of a fluid transport system, i.e. the tube described may define a container in the form of a multi-chamber container, which may be positioned as part of a fluid transport system and thus connected to tubes or pipes for further transport of fluid to and from the container.

[0058] While embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it will be understood that various changes and modifications to the examples can be made without departing from the scope of the invention as claimed.

[0059] The features described in the foregoing description may be used in combinations other than those expressly described.

[0060] Although certain functions are described with reference to certain features, those functions may be implemented by other features, whether or not described.

[0061] Although several features have been described with reference to certain embodiments, those features may be present in other embodiments whether or not they are described.

[0062] Although the foregoing specification has sought to draw attention to those features of the invention which are believed to be particularly important, it is to be understood that the applicant claims protection for any claimable feature or combination of features described above and / or shown in the drawings, whether or not particular emphasis is being placed on them.

Claims

1. A tube for conveying a fluid, comprising: A first passage; a second passageway comprising a pressure sensor connection point extending through a wall of the second passageway; a valve configured to be open when fluid flow through the tube is in a first direction and closed when the fluid flow through the tube is in a second direction opposite the first direction, the pressure sensor connection point being upstream of the valve when the fluid flow is in the first direction and downstream of the valve when the fluid flow is in the second direction; when the valve is in the open state, fluid may be conveyed through the first passageway, and when the valve is in the closed state, fluid may not be conveyed through the first passageway.

2. 2. The tube of claim 1, wherein when the valve is in the open state, fluid can be delivered through the first passageway and the second passageway, and when the valve is in the closed state, fluid can be delivered only through the second passageway.

3. a pressure sensor attached to the pressure sensor connection point for measuring the pressure of the fluid flow through the second passage of the tube. The tube of claim 1 or 2, comprising:

4. The tube of claim 3 , wherein the pressure sensor includes a pressure sensing element in the fluid flow inside the second passage.

5. 4. The tube of claim 3, wherein the pressure sensor connection point is a pressure sensor tap, the pressure sensor tap being connected to a pressure sensing element outside the second passageway.

6. 10. A tube according to any preceding claim, having a circular cross-section.

7. 7. The tube of claim 6, wherein the first passage is annular in cross section and has a first outer diameter, the second passage is circular in cross section and has a second outer diameter, the second passage is concentric with the first passage and the second outer diameter is smaller than the first outer diameter, and the valve is annular in cross section and has an outer valve diameter in the closed state substantially equal to the first outer diameter and an inner valve diameter in the closed state substantially equal to the second outer diameter.

8. 7. The tube of claim 6, wherein the first passage is, in cross-section, a first segment of the tube forming a first portion of the tube, the second passage is, in cross-section, a second segment of the tube forming a second portion of the tube, and the valve is, in cross-section, a segment that encompasses substantially the same cross-section as the first passage when in the closed state.

9. 9. The tube of claim 8, wherein the first segment is a semicircle whose cross-section forms a first half of the tube and the second segment is a semicircle whose cross-section forms a second half of the tube.

10. 2. A tube as claimed in any preceding claim, wherein the second passage comprises an expansion chamber.

11. 2. A tube as claimed in any preceding claim, wherein the second passage comprises a throttle plate, such that the pressure sensor connection point is between the throttle plate and the valve.

12. The tube of claim 11 , wherein the throttle plate includes drainage holes for draining liquid condensate from the tube.

13. 4. A device comprising a tube according to any preceding claim and a pressure sensor according to claim 3, further comprising a processor for receiving a signal from the pressure sensor, a memory and a power source.

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