Improved air flow-rate meter

Abstract

An air-flow meter 500 is disclosed, for use with an air pump 900 and sampling device 200 of an air-sampling system fig. 5, for calibration of the pump, wherein the pump draws air through the open end

Description

FIELD OF THE INVENTION The present invention relates to an air-flow meter for use in systems for air-quality testing. More specifically, but not exclusively, the present invention relates to an improved air flow-rate meter for use with a sampling device and an air pump. BACKGROUND OF THE INVENTION For air-quality testing, monitoring and management, devices are available for the collection of a wide-range of airborne particulates. Such airborne aerosols or particulates may include, but are not limited to: mould spores, dust mites, human skin, insect parts, inorganic particulate, fibres, and pollens. Currently available systems use an air pump for generating a flow of air through a testing cell (also referred to as device). The device sits on the air pump and air is forced to flow through the testing cell or testing device. One such testing cell is described in US Patent No. US5,693,895, which dates back to 1996. A commercially available testing cell based upon this patent is known in the industry as the Air-O-Cell® which is offered by Zefon International. As shown in Figure 3 of US Patent No. US5,693,895, the sampling cell 44 comprises a cell base 48 and a cell cover 58. The cell base 48 has a flat floor 50 and a peripheral upstanding rim 52. An outlet tube 54 is provided through floor 50, preferably at approximately the centre of the floor. A ledge 56 is provided between the inner surfaces of rim 52 and floor 50 to hold a support sheet. As seen in Figure 3 of US Patent No. US5,693,895, the corners of support plate are engaged by ledge 56, leaving a space between the support sheet edges and rim 52 open for passage of air as indicated by the arrows in Figure 4 of US Patent No. US 5,693,895. Cell cover 58 includes a top wall 60 having a peripheral lip 62 sized to fit within rim 52 of base 48. A transverse block 63 formed with top wall 60 has a transverse slit 64 having a V-shaped cross section slot ending in a narrow rectangular opening. In use, a tube 42 is connected to outlet 54 and the assembled sampling cell 44 is placed at the desired sampling location, oriented in any desired attitude. The second end of tube 42 is secured to vacuum pump 40, which may be at any selected location including those well away from the sampling cell. As vacuum pump 40 runs, air enters at high velocity through slot 64, bends essentially 90 DEG adjacent to a tacky layer 46 and passes around the edges of support to outlet 54. Inertial forces cause particles entering through slot 64 to impact tacky layer 46 and adhere thereto. The pump is operated for the desired period and shut off. Sampling cell 44 is removed from tube 42. In US 5 5,693,895 it is disclosed that the openings are covered with caps and / or plugs, and taken to an analysis station for microscopic or other analysis of the captured particles. In use, currently commercially available sampling systems need to be calibrated before use. The air flow rate and test duration will impact the amount of particulate that is trapped in a sampling cell during the test. For a test to generate meaningful results that can be confidently compared to other tests and from which meaningful conclusions can be drawn, it is necessary for the tests to be conducted in standardised and controlled test conditions. It will readily be understood that if a test is conducted at an air-flow rate of 15 litres per minute and another test is conducted at an airflowrate of 13 litres per minute that the results of those tests cannot reasonably and meaningfully be compared. The analysis conducted on the content of the sampling devices tested under such different conditions may vary and therefore the testing of the air-quality at the test location, is not necessarily meaningful. Currently commercially available testing systems that utilise commercially available sampling cells, do have a set or test criteria recommended for conducting the test. Such instructions may include use of rotameter calibrated to a primary standard, soap bubble tube / meter or a dry bubble meter to calibrate the sampling pump to a flow rate of 15 Ipm. A rotameter is a device that measures volumetric flow-rate in a tube and a bubble position relative to a gradient or meter provides an analogue gauge of the flow-rate. The measurement accuracy of known such rotameters is not clear and the analogue gauge does not always provide a clear and accurate reading - especially if a user is not being vigilent and trying to rush. Without accurate calibration of the flow-rate of the air-pump, the accuracy of the test is compromised. It is desirable to conduct tests accurately, to a standardised form and for the variables associated with the test itself to have as little impact as possible on the test so that the test results are meaningful and can be used with confidence. The present invention seeks to improve upon or at least mitigate against certain fall-backs of the known prior art. SUMMARY OF INVENTION According to a first aspect of the invention for which protection is sought, there is provided an airflow meter for use in an air-sampling system comprising an air pump and a sampling device, the air-flow meter comprising: a housing having an interior and an exterior; a sensor for measuring air-flow-rate; and a connector for connecting the body to an air-sampling device used in the air-sampling system; the connector configured and arranged for attachment to an air-inlet of a sampling device used in the air-sampling system. Optionally, the housing is formed from first and second housing parts. Optionally, said sensor for measuring air-flow-rate is an ultrasonic volumetric flow-rate sensor. Optionally, said sensor provides a digital output of air-flow rate. Optionally, the air-flow meter comprises a digital output device. The digital output device may comprise a display screen. Optionally, the digital output device comprises a control means associated with the sensor and display screen; and the control means configured for outputting to the display screen graphics, data, infographics and instructions, a measurement of air-flow rate, and / or units of measurement. Optionally, said connector has an end configured to mechanically couple to a first end of the said sensor for measuring air-flow rate; and wherein a second end of the connector is affixed to an interior of the housing, extends out of said housing, and is configured to mechanically couple to an air-inlet of a sampling device. Optionally, the first and / or second housing parts comprise internal formations securely holding the connector and / or the sensor. According to another aspect of the invention for which protection is sought, there is provided an air sampling system comprising an air-flow meter according to any preceding paragraph, an air pump and a sampling device, the sampling device comprising: a base-section comprising: a body having an interior and an exterior; a supporting component disposed within the interior of the body onto which a sampling slide can be deposited; a connector for connecting the base-section to an air-pump, the connector having first and second open ends, the first open-end of the connector being positioned within the interior of the body proximate to said supporting component; and a first closure cap hingedly connected to the base-section for fitting to and for covering said second open-end of the connector; and a top-section comprising: a body having an interior and an exterior; an air inlet for enabling air to be drawn into the air-flow meter when in use, the air inlet having first and second open ends, the first open-end of the air inlet being positioned proximate to an exterior of the body of the top-section, the second open-end of the air inlet being positioned within the interior of the body of the top-section; and a second closure cap hingedly connected to the top-section for covering said first open-end of the air inlet. Optionally, said first closure cap is integrally moulded with the body of the base-section, wherein the first closure cap is hingedly connected to an exterior of the body of the base-section by a first hinge structure sized shaped and configured such that the first hinge structure is operable to hold the first closure cap in an open position, wherein the first closure cap is spaced from the body of the base-section and first closure cap is not attached to the second open-end of the connector. Optionally, the second closure cap is integrally moulded with the body of the top-section, wherein the second closure cap is hingedly connected to an exterior of the body of the top-section by a second hinge structure sized shaped and configured such that the second hinge structure is operable to move the second closure cap from a closed position wherein the second closure cap is attached to and covers the first open-end of the air inlet; and wherein the second hinge structure is operable to hold the second closure cap in an open position wherein the second closure cap is spaced from the body of the top-section. Optionally, the second hinge structure has a central pivot and a wing portion either side thereof. Optionally, the central pivot facilitates movement of the second closure cap between said closed position and said open position; and the wing portions serve to hold the second closure cap in said open position. Optionally, the second hinge structure is connected to the exterior of the body of the top-section at an elevation that is off-set from an elevation containing the first open-end of the air inlet. Optionally, the second hinge structure comprises: an anchoring panel; one or more or a series of adjacent hinge lines; a first hinge panel; a second hinge member; a second hinge panel; a third hinge line; and a reinforcing member. Optionally, the anchoring panel is a moulded formation forming a protruding part of a side wall of the top-section body. Optionally, the one or more or series of adjacent hinge lines includes one or more living hinges, the one or more or series of adjacent hinge lines traverse a beveled corner between the side wall and a deck of the top-section body when the second closure cap is in the closed position. The one or more or series of adjacent living hinges may allow the first hinge panel to pivot from said closed position, wherein the first hinge panel is substantially parallel to the upper-side of deck; to an open position wherein the first hinge panel can rest in a plane that is substantially orthogonal to said side wall. Optionally, the reinforcing member is a substantially triangular moulded section between the first hinge panel and the second hinge panel and wherein, the reinforcing member maintains an angle between the first hinge panel and the second hinge panel. Optionally, the second hinge panel forms part of a side wall of the second closure cap. Optionally, the first hinge structure comprises: first, second and third hinge lines a first hinge panel, a second hinge panel and a third hinge panel, the first living hinge line may be operable to pivot the first hinge panel away from an exterior of the body, the second living hinge line may be operable to pivot the second hinge panel away from the first hinge panel, and the third living hinge line may be operable to pivot the third hinge panel away from the second hinge panel. Optionally, the first hinge panel has a smaller height than the second hinge panel; and the second hinge panel has a smaller height than the third hinge panel. Optionally, when the first closure cap is in said open position, it is spaced outwardly away from an exterior of the base-section body substantially by the combined heights of the first hinge panel and the third hinge panel; and the first closure cap is spaced downwardly from the top of the basesection body, by about twice the height of the second hinge panel. Optionally, the first hinge structure comprises: one or more or a series of hinge lines and a strap portion 186 extending therefrom at another end of which the first closure cap is formed. Optionally, said one or more or a series of hinge lines allow the strap portion to pivot from around a bottom side edge of the body of the base-section. Optionally, said hinge portion can pivot up to or greater than about 270° between the closed position and the open position. Optionally, the first hinge structure is operable to move the first closure cap from being on top of the end of the connector underneath the body of the base-section; to being held at an elevation above a deck of the top-section of the sampling device 200 and spaced from the side wall of the top-section. Optionally, the hinge of the first closure cap is connected to the exterior of the body of the basesection at an elevation that is off-set from an elevation containing the second open-end of the connector. Optionally, when the sampling device according to any preceding relevant paragraph is disposed on an air pump with the connector of the base-section of the sampling device connected to the air-pump, the first and second closure caps are both in an open position, and the first and second closure caps are on opposite sides of the sampling device. Optionally, the first and second closure caps are both disposed above the top of the top-section of the sampling device. Optionally, the base-section comprises a first-part of a two-part connecting mechanism located at an upper region of the base-section body; and the top-section comprises a second-part of a two-part connecting mechanism located at a lower region of the top-section body; the second-part of the two-part connecting mechanism operable to releasably connect to the first-part of the two-part connecting mechanism for releasably securing the top-section to the base-section. Optionally, the two-part connecting mechanism facilitates the holding of the sampling slide within the sampling device in an assembled condition. Optionally, the body of the base-section is substantially cylindrical in shape. Optionally, the first-part of the two-part connecting mechanism provided by the base-section is an internal screw-thread; and the second-part of the two-part connecting mechanism provided by the top-section is an external screw-thread. Optionally, the body of the top-section comprises a side wall, the external screw-thread is provided on the side wall. Optionally, the side wall is substantially circular in cross-sectional shape, with one or two flattened end portions. Optionally, the base-section comprises means for improving a user’s grip of the base-section. Optionally, the sampling device comprises a sampling slide and has the top and base-sections attached in an assembled condition with the first and second closure caps closed. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1A is a perspective view of a sampling device usable with an air-flow meter according to an embodiment of the invention; Figure 1B is a perspective view from the bottom of the sampling device of Figure 1 A, shown with both a top-section hinged cap; and a base-section hinged cap, held in an open position; Figure 2A is a perspective view from the top of a sampling device for use with an air-flow meter according to the present invention; Figure 2B is a top plan view of the air-flow meter of Figure 2A, shown with both a top-section hinged cap; and a base-section hinged cap, held in an open position; Figure 2C is a perspective view from the bottom of the sampling device of Figure 2A; Figure 2D is a side-end plan view of the sampling device of Figure 2A, shown with both its hinged cap held in an open position; Figure 3A and 3B are perspective views of an air-pump having located thereon and attached thereto, the sampling device of Figure 2A. The sampling device is shown with both its topsection hinged cap; and its base-section hinged cap, held in an open position and the air-flow meter is located on and attached to the air-pump, unhindered by the presence of the open hinged caps; Figure 4A is an exploded perspective view of the components of an air-flow meter according to various embodiments; Figure 4B is a perspective view of an air-flow meter according to various embodiments; Figure 5 is a front perspective view of an air-pump having located thereon and attached thereto, the sampling device of Figure 2A; and wherein an air-flow meter assembled from the parts shown in Figure 4 is connected to the sampling device for measuring air-flow therethrough; Figure 6 is a front perspective view of another air-pump having located thereon and attached thereto, the sampling device of Figure 1A; and wherein an air-flow meter assembled from the parts shown in Figure 4 is connected to the sampling device for measuring air-flow therethrough; DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Detailed descriptions of specific embodiments of the air-flow meters and testing systems are disclosed herein. It will be understood that the disclosed embodiments are merely examples of the way in which certain aspects of the invention can be implemented and do not represent an exhaustive list of all of the ways the invention may be embodied. As used herein, the word “exemplary” is used expansively to refer to embodiments that serve as illustrations, specimens, models, or patterns. Indeed, it will be understood that the air-flow meters and testing systems described herein may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimised to show details of particular components. Well-known components, materials or methods are not necessarily described in great detail in order to avoid obscuring the present disclosure. Any specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the invention. Figure 1A is an exploded perspective view of the components of a sampling devicelOO. The assembled sampling device 100 is shown in Figures 1A and 1B. The sampling device 100 may also be referred to as a cell, trap or device. The sampling device 100 comprises a top-section 10 and a base-section 16. A sampling slide (not shown) is housed in the base-section 16, clamped between the base-section 16 and top-section 10. The sampling slide may be securely held in place by the secure attachment of the top-section 10 to the base-section 16. In the perspective views of Figures 1A and 1B, it can be seen that the base-section 16 comprises a first closure cap 80 hingedly connected thereto; and the top-section comprises a second-closure cap 80. In Figures 1A and 1B, the sampling device 100 is shown with both its top-section hinged cap 30; and its base-section hinged cap 80, held in an open position. The sampling device 100 itself is subject to separate patent protection and is described in cross-referenced GB patent application GB 2407119.3, the contents of which are incorporated herein by reference. As described therein, the base-section 16 comprises a body 48. The body 48 may be substantially cylindrical in shape. The body 48 has an exterior surface and an interior surface 47. A deck 55 is positioned within an interior section of the body 48. A connector 66 depends from an underside of the deck 55 toward an open bottom of body 48 (see Figure 1B). A series of supports (not shown) upstand from a topside of the deck 55 toward an open top of body 48. A sampling slide (not shown) is housed in the base-section 16 by being placed on supports. The supports are arranged to provide, between them, a sufficiently large and even supporting surface for the sampling slide. The supports are arranged around a connector 66 and do not obscure an open end (not shown) of the connector 66 to facilitate good airflow through the body 48 and in particular over the sampling slide. The connector 66 is configured such that base-section 16 can be connected directly to an air-pump - see Figure 6 for an optional non-limiting example of an air-pump 900’, to which the sampling device 100 is attached. In Figure 6, first and second caps 30, 80 are not shown in order to show the device 200 located on the pump 900’ with an air-flow meter 500 of the present disclosure attached thereto. Returning to Figure 1B, the connector 66 has first and second open ends 64. The second open end 64 is configured for connection to an air-pump 900’, preferably, but nevertheless optionally, the second open end 64 is configured for direct connection to an air-pump 900’ such that no intermediate connectors or converters, tubes or other components are required. The first open end (not shown) is optionally positioned substantially centrally in the deck 55, and proximate to a centre region of the sampling slide when located in the base-section 16. Optionally an exterior surface of the body 48 comprises gripping features such as shaped regions 87 which beneficially make it easier for a user and a technician at an analysis laboratory to handle and open the sampling device 100. The gripping features may be useful when attaching the airflow meter 500 of the present disclosure directly to the sampling device 100. As illustrated in Figures 1A and 1B, the top-section 10 includes a deck 18 from which an air-inlet unit 32 extends. The air-inlet unit 32 has a peripheral rim 35 and a V-shaped internal cross-section defined by inner walls 37 which lead to a narrow opening (not shown). The opening is a slot-like, substantially rectangular or stadium-shaped, opening. The rim 35 defines a first open end 35 of the air-inlet unit 32; and the slot-like opening defines a second-open end of the air-inlet unit 32. Without being limited to the specific configuration of air-inlet 32 illustrated and described herein; it is known from US5,693,895 that in the collection of particles having diameters greater than about 2pm, an angle between the inner walls 37 of the air-inlet unit 32 may optionally by between about 40° and about 60°. Again, optionally, and without limitation to that described and illustrated herein, it may be preferential for the inner walls 37 to be smoothly tapered; and for a width of the first open end 35 of the air inlet unit 32 to be at least about 10 times as wide as the width of the slot-like, second-open end of the air-inlet unit 32. Notwithstanding this, and notwithstanding the air-inlet unit 32 illustrated, it is anticipated that in other embodiments of the present invention, the configuration of the air-inlet unit 32 may differ from that shown and described herein. For use in an environmental monitoring system, a sampling slide, comprising a tacky layer, is placed inside the base-section 16 of the sampling device 100 onto supports. The tacky layer or adhesive is provided to collect air-borne particles from air flowing through the sampling device 100. The top-section 10 is placed into the body 48 of the base-section 16 and is releasably, yet securely attached thereto by means of an optional screw-threaded mechanism. A second embodiment of sampling device 200 is shown in Figures 2A to 2D. In the illustration of the second embodiment sampling device 200, like numerals have, where possible, been used to denote like parts, albeit with the addition of the prefix “100” to indicate that these features belong to the second embodiment. The second embodiment shares many common features with the first embodiment and therefore only the differences from the embodiment illustrated in Figures 1A to 1B will be described in any greater detail. The assembled sampling device 200 is shown in Figure 2A. The sampling device 200 may also be referred to as a cell, trap or cassette 200. The sampling device 200 comprises a top-section 110 and a base-section 116. A sampling slide is housed in the base-section. In the perspective view of Figure 2A, it can be seen that the top-section 110 comprises a first closure cap 130 hingedly connected thereto; and the base-section 116 comprises a second-closure cap 180. In Figure 2A, the sampling device is shown with both its top-section hinged cap 130; and its basesection hinged cap 180, held in an open position. As illustrated in Figures 2A to 2D, the base-section 116 comprises a body 148. The body 148 may be cassette-like in shape. A connector 166 depends from an underside of the deck 155 toward an open bottom of body 148 (see Figure 2C). The base-section 116 includes the connector 166 so that base-section 116 can be connected directly to an air-pump (an optional non-limiting example of an air-pump 900 is shown in Figures 3A, 3B and 5). The connector 166 has first and second open ends 164. The second open end 164 is configured for connection to the air-pump 900, preferably, but nevertheless optionally, the second open end 164 is configured for direct connection to the air-pump 900 such that no intermediate connectors or converters, tubes or other components are required. The first open end (not shown) is optionally positioned substantially centrally in the deck, and proximate to a centre region of the sampling slide when located in the base-section 116. As illustrated in Figures 2A, 2B and 2D, the top-section 110 includes a deck 118 from which an air-inlet unit 132 extends. The top-section 110 includes the air-inlet unit 132, which optionally is similar to that of the first embodiment and is not described further. The sampling devices 100, 200 once assembled can be attached to an air pump 900, 900’ (see Figures 3A to 6). At a test site, a steady flow of air, is drawn in through the first open end 35, 135 of the air-inlet unit 32, 132 of the top-section 10, 110; and through the device 100, 200. Aerosols i.e. particulates, such as mould spores, dust mites, human skin, insect parts, inorganic particulate, fibres, and pollens as non-limiting examples, that may be present in air are caught by the tacky layer. The sampled air flows out through the second open end 64, 164 of connector 66, 166 of the base-section 16, 166 (into the air pump 900, 900’). An air-quality sampling test is performed for a specified duration based upon the test-type, environment and other specified test criteria. In prior art devices an air-flow rate of an air pump is measured. In the present disclosure, in contrast, an air flow-rate through the sampling device 100, 200 is measured. It is known from the prior art that before testing can be commenced, it is important to calibrate the air-flow. In prior art systems an analogue-gauged, rotameter has been used to measure volumetric air-flow rate through an air-pump. The air-flow meter 500 of the present invention has been developed as an improvement to the rotameters previously used. Advantageously, the air-flow meter 500 taught herein has been configured to connect directly to a sampling device 100, 200. In this way, an accurate measurement of air-flow-rate going into a test sampling device 100, 200 can be taken. This is in stark contrast to the prior art systems where a rotameter is connected to an air-pump and measurement taken of air-flow of the pump itself without the sampling cell in situ. The applicant has discovered, that a difference in air-flow rate may exist between the air-flow rate at the pump 900, 900’ itself versus the air-flow rate at the sampling device 100, 200. Without being limited to any particular theory it is thought that air flow rate is affected by the sampling device 100, 200 itself. Indeed, the air-inlet unit 32,132 thereof is designed to accelerate air flowing into the open end 35, 135 using the V-shaped inner walls 37, 137 and funnelling the air through the slot-type opening. Since it is important for the air flow rate not just to be known, but to be a certain rate for airborne particles to be caught by the tacky layer (for example, calibrated to a specific level such as 15 litres per minute), this determination by the applicant is significant. Since the location at which air-flow is actually measured may be significant, it is highly advantageous that the air-flow rate meter 500 of the present invention has been developed. In the prior art systems, it may have been unknown that for tests where an air-pump was measured as having an air-flow rate of say the requisite 15 litres per minute, the actual air flow rate into a sampling cell could have been different by 1 - 2 litres per minute. Since the air-flow rate through the sampling device is an important factor for trapping aerosols of a certain size (e.g. 2pm), tests need to be conducted at a correct air flow-rate. By providing a new and improved flow-rate meter 500 capable of coupling directly to a sampling device 100, 200 air-inlet unit 32, 132 the present invention offers a significant improvement in the accuracy, consistency and repeatability of tests. Furthermore, it has additionally been recognised that variables such as temperature, humidity and altitude can affect the volumetric air-flow reading provided by prior art rotameters used in prior art testing systems. Accordingly, when used, for example in different US States where such atmospheric conditions can vary significantly, a rotameter measured air-pump air-flow rate for calibration of an air-quality test conducted using a sampling device of the prior art might have been thought to have been set at the requisite flow-rate of 15 litres per minute, but this reading might have been quite different from the actual air-flow rate into the sampling device in a hot and humid environment as compared to a cooler, drier climate. The air-flow rate meter 500 according to various embodiments is shown in Figure 4 in exploded view. It can be seen that the air-flow rate meter 500 comprises a housing optionally formed from first and second housing parts 500a, 500b. The air-flow rate meter 500 according to various embodiments also comprises a volumetric flow-rate sensor 507, a first connector 503, a second connector 501, a digital output device 502 and a power source (cell, battery or rechargeable unit or connection to couple to mains electricity). A first end of the first connector 503 is configured to mechanically couple to a first end of the volumetric flow-rate sensor 507. A first end of the second connector 501 is configured to mechanically couple to a second end of the volumetric flow-rate sensor 507. A second end 503a of the first connector 503 is configured to protrude from an opening in the housing 500. A second end 501a of the second connector 501 is configured to mechanically couple, preferably directly, to an opening 35, 135 of an air-inlet unit 32, 132 of a sampling device 100, 200. In various embodiments the volumetric flow-rate sensor 507 is based on an ultrasonic detecting technology using the principle of TOF (time of flight) measurement. Such volumetric flow-rate sensors are commercially available. For example, in some embodiments, an Ultrasonic Oxygen Sensor Gasboard-8500FS-L40 from Cubic (Fenghuang No.3 Road, Fenghuang Industrial Park, Eastlake Hi-tech Development Zone, Wuhan, 430205, China) may be used as the volumetric flowrate sensor 507 (for specific sensor 507 information see: https: / / en.gssensor.com.cn / UltrasonicOxygenFlowSensor / info itemid 1531 .html). By utilising an ultrasonic detector 507 the flow-rate meter 500 of the present invention mitigates against the affects of atmospheric conditions such as temperature, humidity and altitude; these variables can affect the accuracy of the bubble-based rotameter devices typically used in airflowrate meters for the environmental air-quality testing systems of the prior art. Furthermore, sensors 507 such as the ultrasonic detector described above provide a digital output. In the air-flow rate meter 500 of the presently illustrated embodiment, it can be seen that the volumetric air-flow sensor 507 is associated with a digital output device 502. Optionally, the digital output device 502 is electrically coupled to the sensor 507. The digital output device 502 additionally comprises a display screen and may optionally comprise an additional control means, such as but not limited to a processor. The control means may be associated with and / or coupled to the sensor 507 and display screen. Accordingly in dependence upon application, end user type and test configuration requirements as examples, the control means may be configured for outputting to the display screen various graphics, data, infographics and instructions and so on. Preferably, and as indicated in Figure 4B, a measured air-flow rate and units of measurement may be clearly displayed. This is advantageous because it will allow a user of the system to easily determine a current air flow rate and if necessary, adjust an air pump 900, 900’ to achieve a desired air flow rate, for example 15 Ipm. Referring again to Figure 4A, the housing 500a, 500b is preferably made of a robust material. Optionally the first and second housing parts 500a, 500b are moulded from plastics material. Preferably at least a portion of the first housing 500a comprises a window 502a for enabling the screen of the digital output device 502 to be viewed through the first housing 500a. In one embodiment the window 502a is moulded from a sufficiently transparent plastic material. In other embodiments, the window 502a is an aperture. The first and second housing parts 500a, 500b preferably interconnect for assembly of the housing unit 500a / 500b. Optionally, the first housing part 500a comprises a first part of a two-part interlocking mechanism. Optionally, the second housing part 500b comprises a second part of a two-part interlocking mechanism 504. The two-part interlocking mechanism may take many and various forms, including but not limited to locking posts 504 disposed internally at corners of the second housing part 500b and complementarily positioned, locking pins (not shown in Figure 4A) which locate within the locking posts and snap fit thereto. Within the first and / or second housing parts 500a, 500b, internal formations 505, 506 are provided for securely holding (optionally by snap-fit) the first connector 503, the second connector 501 and / or the sensor 507. By mechanically fixing the internal components to the first and / or second housing parts 500a, 500b, the air-flow-rate meter 500 is a rugged, portable measuring device that can be taken on site and reliably utilised for accurate measurement of air-flow rate. Reference has already been made to Figures 5 and 6 wherein the use of an air-flow-rate meter 500 during a calibration sequence is illustrated. It is envisaged that to calibrate the pump 900, 900’ to ensure that it is operating at the correct pump-rate to create the desired air-flow rate into a sampling device 100, 200, a sampling device 100, 200 will be used merely to establish and calibrate the air-flow. This calibration cassette 100, 200 may then be discarded; and a fresh sampling device cassette 100, 200 used in its place, with the air-flow-rate meter 500 removed, the actual test can be conducted for the appropriate duration, the standard test conditions having accurately been established. Whereas it is envisaged that the air-flow-rate meter 500 can be constructed in a variety of ways without departing from the scope of the present invention. In the illustrated example, the second connector 501 has a second end 501a configured to mechanically couple, preferably directly, to an opening 35, 135 of an air-inlet unit 32, 132 of a sampling device 100, 200. In co-pending GB patent application GB 2407119.3, the improved sampling devices 100, 200 are described in detail. It is described therein how advantageously, the sampling devices 100, 200 provide at least one of a top-section 10, 110 hinged cap 30, 130; and a base-section 16, 116 hinged cap 80, 180. Preferably, and as shown in Figures 1A to 2D, the sampling devices 100, 200 comprise both a top-section 10, 110 hinged cap 30, 130; and a base-section 16, 116 hinged cap 80, 180. Optionally, in various embodiments the top-section 10, 110 hinged cap 30, 130 is an integrally formed part of the top-section 10, 110. Optionally, in various embodiments the top-section 10, 110 is a plastics moulded component and the hinged cap 30, 130 is an integrally moulded part of the top-section 10, 110. Optionally, the top-section 10, 110 may be moulded from recyclable polypropylene. Optionally, in various embodiments the top-section 10, 110 cap 30, 130 or cover 30, 130 is sized, shaped and configured to securely fit onto and to cover the first open end 35, 135 of the air inlet unit 32, 132. Optionally, the cover 30, 130 is sized and shaped in a complementary manner to the size and shape of the open end 35,135 of the air inlet unit 32, 132. Optionally, the cover 30, 130 is provided with a side wall 42, 142, which comprises, on an inner surface thereof, a moulded, shaped feature, such as one or more ribs or protruding sealing mouldings, that are configured to push past and then co-operate with the lipped rim 35, 135 such that the cover 30, 130 can be relatively securely, yet releasably, affixed onto the open end 35, 135 of the air inlet unit 32, 132. Optionally, a tab 41, 141, which may be called a thumb-tab 41, 141 or release tab 41, 141 is provided on the cover 30, 130 for assisting with the release of the cover 30, 130 from its attachment to the lipped rim 35, 135 at the open end 35, 135 of the air inlet unit 32, 132. Optionally, in various embodiments the base-section 16, 116 hinged cap 80, 180 is an integrally formed part of the base-section 16, 116. Optionally, in various embodiments the base-section 16, 116 is a plastics moulded component and the hinged cap 80, 180 is an integrally moulded part of the base-section 16, 116. Optionally, in various embodiments the base-section 16, 116 cap 80, 180 or cover 80,180 is sized, shaped and configured to securely fit onto and to cover the second open end 64, 164 of the connector 66, 166. Optionally, the cover 80, 180 is sized and shaped in a complementary manner to the size and shape of the second end 64, 164 of the connector 66, 166. Optionally, the cover 80, 180 can be relatively securely and releasably press-fit, snap-fit, friction fit or otherwise releasably affixed onto the second end 64, 164 of the connector 66, 166. Optionally, a tab 91, 191 which may be called a thumb-tab 91, 191 or release tab 91, 191 is provided on the cover 80, 180 for assisting with the release of the cover 80, 180 from its attachment to the second end 64, 164 of the connector 66, 166. As illustrated in Figures 1A to 2D, hinge structures 27 / 29, 122 / 124 / 126 / 127 / 129 have been carefully innovated. As shown, the hinges 27 / 29, 122 / 124 / 126 / 127 / 129 have been configured such that the hinge structures hold the covers 30, 130 in a stable state, away from the top-section 10,110, in the open condition (as shown in Figures 1 A, 1B, 2Ato3B). Because the hinge structure 27 / 29, 122 / 124 / 126 / 127 / 129 holds the cover 30, 130 in a stable state, away from the top-section 10, 110 in the open condition; during the test, the cover 30, 130 does not interfere with air-flow into the air inlet unit 32,132. Furthermore, the hinges 27 / 29,122 / 124 / 126 / 127 / 129 are beneficially structured to ensure that the covers 30, 130 do not interfere with the air pump 900, 900’ onto which the sampling devices 100, 200 are placed during testing. As shown in Figures 1A, 1B, 2A- 3B the base-section 16, 116 hinges are configured such that, in the open condition, the hinge structures hold the covers 80, 180 in a stable state and away from both the connector 66, 166 of the base-section 16, 116; and the air-inlet unit 32, 132 of the topsection 10 (as shown in Figure 1A). Beneficially, because the hinge structures hold the cover 80, 180 in a stable state, away from the base-section 16, 116 and away from the air-inlet unit 32, 132 of the top-section 10, 110; during the test, the covers 80, 180 do not interfere with air-flow out of the connector 66, 166. Furthermore, the hinges have beneficially been structured to ensure that the covers 80, 180 do not interfere with the air pump 900, 900’ onto which the sampling devices 100, 200 are placed during testing. It is in consideration of the shapes of air inlet units 32, 132, top-section 10, 100 hinge structures 27 / 29, 122 / 124 / 126 / 127 / 129; and base-section hinge structures that the second end 501a of second connector 501 has been shaped, sized and configured as illustrated in Figure 4A (also see Figures 5 and 6). In other envisaged arrangements, the second end 501a of second connector 501 may be differently configured, shaped and sized compared to that shown in order to connect with a differently sized and shaped air-inlet unit 32, 132; and / or to accommodate a differently sized and shaped connector cap / hinge structure. It can be appreciated that various changes may be made within the scope of the present invention, for example, the size and shape of the body, display and connectors and so on may be adjusted to accommodate sampling slides and air-pumps of differing size or shape. It will be recognised that as used herein, directional references such as "top", "bottom", "front", "back", "end", "side", "inner", "outer", "upper" and "lower" do not necessarily limit the respective panels to such orientation, but may merely serve to distinguish the relative orientations of components from one another. As used herein, the terms “hinged connection” may refer to various ways of define hinge features 5 of the device, to facilitate folding or articulating portions of the devices with respect to one another, Any reference to hinged connection or living hinge should not be construed as necessarily referring to a single hinge line only; indeed, it is envisaged that hinged connection can be formed in many ways without departing from the scope of the invention.

Claims

1. An air-flow meter for use in an air-sampling system comprising an air pump, the air-flow meter comprising:a housing having an interior and an exterior;a sensor for measuring air-flow-rate; anda connector for connecting the body to an air-sampling device used in the airsampling system; the connector configured and arranged for attachment to an air-inlet of a sampling device used in the air-sampling system.

2. An air-flow meter according to claim 1 wherein the housing is formed from first and second housing parts.

3. An air-flow meter according to claim 1 or 2 wherein said sensor for measuring air-flow-rate is an ultrasonic volumetric flow-rate sensor.

4. An air-flow meter according to claim 3 wherein said sensor provides a digital output of airflow rate.

5. An air-flow meter according to any preceding claim further comprising a digital output device.

6. An air-flow meter according to claim 5 wherein the digital output device comprises a display screen.

7. An air-flow meter according to claim 5 wherein the digital output device comprises a control means associated with the sensor and display screen; and the control means configured for outputting to the display screen graphics, data, infographics and instructions, a measurement of air-flow rate, and / or units of measurement.

8. An air-flow meter according to any preceding claim wherein said connector has an end configured to mechanically couple to a first end of the said sensor for measuring air-flow rate; and wherein a second end of the connector is affixed to an interior of the housing, extends out of said housing, and is configured to mechanically couple to an air-inlet of a sampling device.

9. An air-flow meter according to claim 2, wherein the first and / or second housing parts comprise internal formations securely holding the connector and / or the sensor.

10. An air sampling system comprising an air-flow meter according to any preceding claim, an air pump and a sampling device, the sampling device comprising:a base-section comprising:a body having an interior and an exterior;a supporting component disposed within the interior of the body onto which a sampling slide can be deposited;a connector for connecting the base-section to an air-pump, the connector having first and second open ends, the first open-end of the connector being positioned within the interior of the body proximate to said supporting component; anda first closure cap hingedly connected to the base-section for fitting to and for covering said second open-end of the connector; anda top-section comprising:a body having an interior and an exterior;an air inlet for enabling air to be drawn into the air-flow meter when in use, the air inlet having first and second open ends, the first open-end of the air inlet being positioned proximate to an exterior of the body of the top-section, the second open-end of the air inlet being positioned within the interior of the body of the top-section; anda second closure cap hingedly connected to the top-section for covering said first open-end of the air inlet.

11. An air sampling system according to claim 10 wherein said first closure cap is integrally moulded with the body of the base-section, wherein the first closure cap is hingedly connected to an exterior of the body of the base-section by a first hinge structure sized shaped and configured such that the first hinge structure is operable to hold the first closure cap in an open position, wherein the first closure cap is spaced from the body of the base-section and first closure cap is not attached to the second open-end of the connector.

12. An air sampling system according to claim 10 or 11 wherein the second closure cap is integrally moulded with the body of the top-section, wherein the second closure cap is hingedly connected to an exterior of the body of the top-section by a second hinge structure sized shaped and configured such that the second hinge structure is operable to move the second closure cap from a closed position wherein the second closure cap is attached to and covers the first open-end of the air inlet; and wherein the second hinge structure is operable to hold the second closure cap in an open position wherein the second closure cap is spaced from the body of the top-section.

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