An anemometer suitable for calibrating a gas sampler, and a method for calibrating a gas sampler using such an anemometer.

Abstract

This application relates to an anemometer device suitable for calibrating a gas sampler, particularly at low flow rates, and to a method for calibrating a gas sampler using such an anemometer device.

Description

Technical Field

[0001] The present application relates to an anemometer device particularly suitable for calibrating gas samplers at low flow rates, and to a method for calibrating a gas sampler using such an anemometer device. Background Art

[0002] Gas sampling, particularly air sampling, is frequently performed in various clean rooms and manufacturing environments that require low levels of particles, such as clean room environments for electronic device manufacturing and aseptic environments for the manufacture of pharmaceuticals including sterile pharmaceuticals and biological products.

[0003] Such gas sampling is generally performed using particle monitoring systems such as microbial gas samplers, active gas samplers, and particle counters. Such gas samplers and particle counters are particularly advantageous because they can sample a constant volume of gas and determine contamination risk in clean rooms and manufacturing environments.

[0004] Examples of microbial gas or air samplers, and examples of methods for sampling, detecting and / or characterizing particles including collection, growth and analysis of viable biological particles such as microorganisms, are disclosed in EP0964240A1. This device comprises an integrated sampler and an impaction surface such as a receiving surface for culture medium for collecting biological particles. Collected particles are typically incubated to grow viable particles, after which they are analyzed by various techniques including visual inspection, microscopic observation, fluorescence or autofluorescence, and ATP detection.

[0005] In a particle counter, a laser beam is irradiated onto a gas flow to be monitored. Particles crossing the laser beam generate a signal, which is detected by a photomultiplier tube. The output of the photomultiplier tube is connected to a plurality of amplifiers with different gain stages, and the number and size of particles can be identified by evaluating the signal, more specifically the amplitude of the signal.

[0006] Since the amount of gas passing through a gas sampler is the product of the gas flow rate and time, obtaining reproducible results requires either continuously measuring the gas flow rate of the gas sampler or (as a more feasible method) setting it to a precisely predetermined value. This necessitates a simple yet accurate calibration method and apparatus.

[0007] Commercially available calibration devices for gas or air samplers include the MAS-100(registered trademark) Regulus, available from Merck KGaA in Germany and MBV AG in Stäfer, Switzerland. This is an anemometer that uses a fan to correlate the gas velocity with its respective flow rate, and can calibrate gas flow rates from 50 l / min to 200 l / min.

[0008] Other anemometers utilize, for example, pressure drops, the Coriolis effect, the Venturi effect, and / or temperature effects that occur within laminar flow elements. For instance, the TSI 5000 series digital flowmeter offered by TSI Corporation in Shoreview, Minnesota, is an all-in-one gas flowmeter that integrates flow, absolute pressure, and temperature sensors.

[0009] U.S. Patent Application Publication No. 2001 / 0029777A1 discloses a self-normalizing flow sensor that normalizes the flow rate of fluid in a main channel. U.S. Patent Application Publication 2014 / 0208755A1 discloses a method and system for measuring mass flow rate in a portion of a flow path within an intake duct of a gas turbine engine. U.S. Patent Application Publication No. 2015 / 0192445A1 relates to a microprocessor-based thermal dispersive mass flow meter using a temperature sensing element in the flow sensor probe. U.S. Patent Application Publication 2020 / 0049541A1 discloses a sensor device and method for measuring the flow rate of shielding gas in a welding apparatus.

[0010] However, currently available anemometers still have significant drawbacks in calibrating gas samplers due to excessive pressure drops, difficulty in reliably determining low flow rates due to inertia, baseline drift, and / or increased relative uncertainty as flow rates decrease.

[0011] Furthermore, in order to accurately and reproducibly measure relatively low flow rates of approximately 30 l / min or less, it is necessary to ensure a consistent laminar gas flow at least within the measurement range, that is, to completely avoid (or at least minimize as much as possible) turbulence in the laminar gas flow.

[0012] Therefore, the industrial sector still demands reliable and easy-to-use anemometers suitable for calibrating gas samplers across a wide flow rate range, especially in the low flow rate range of 15 l / min or less. Furthermore, such anemometers should ideally be portable, easy to assemble, and digital. [Overview of the project] [Problems that the invention aims to solve]

[0013] To our surprise, the inventors have discovered that the above objectives can be achieved individually or in any combination by the anemometer device and calibration method of the present invention.

[0014] Therefore, this application provides an anemometer device comprising the following components. (i) A duct having a maximum inner width R, comprising a first open end and a second open end, which guides gas from the first open end ("inlet") to the second open end ("outlet"); (ii) A floral laminator covering the first open end of the duct; and (iii) A thermal anemometer positioned inside the duct at a distance D from the floral laminator.

[0015] The present application also provides a method for measuring the actual gas flow rate of a gas sampler, the actual gas flow rate being up to 28.3 l / min (preferably 1 l / min or more), the method comprising the steps of preparing a gas sampler, preparing an anemometer device, attaching the second open end of the anemometer device to the gas inlet of the air sampler, and determining the actual gas flow rate.

[0016] An anemometer device is particularly suitable as a device used for calibrating a flow rate calibration device, i.e., a gas sampler. Therefore, this application also provides a method for calibrating a gas sampler, the method of which A method for calibrating a gas sampler, (a) A step of providing a gas sampler to be calibrated; (b) the step of providing the aforementioned anemometer device; (c) the step of attaching the second open end of the anemometer device to the gas inlet of the gas sampler; and (d) Steps to calibrate the gas sampler Includes. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic cross-sectional view of the anemometer device (1) of the present invention, in which the flora laminator (4) is installed on the duct (2). [Figure 2] Figure 2 is a schematic cross-sectional view of the anemometer device (1) of the present invention, in which the flora laminator (4) is installed inside the duct (2). [Figure 3] Figure 3 is a top view schematic diagram of a flora laminator (4, 4') equipped with a hexagonal channel (7). [Figure 4] Figure 4 shows the pressure drop at various flow rates for the anemometer device described herein and a commercially available fan-type anemometer. [Modes for carrying out the invention]

[0018] As used herein, the term "regular polygon" refers to a polygon with all angles equal and all side lengths equal, and an n-sided regular polygon has n-fold rotational symmetry. In general, the present specification relates to an anemometer apparatus comprising a duct, a flow laminator, and a gas or air velocity sensor.

[0019] The shape of the duct is not particularly limited as long as it is suitable for guiding gas from a first open end ("inlet") to a second open end ("outlet"). The duct is preferably straight, that is, has no bends or curves. In general, the cross-section of the duct may be circular, oval, or polygonal, that is, have the shape of a circle, oval, or polygon (the cross-section of the duct is substantially orthogonal to the longitudinal axis of the duct). Preferably, the duct has a circular cross-section.

[0020] A polygon is an n-sided polygon having n vertices, where n is a natural number and n is 3 or greater. Although there is no particular limitation, for practical reasons, n is desirably at most 100, for example, 80, 70, 60, 50, 40, 30, or 20. It should be noted that as n increases infinitely (n→∞), the n-sided polygon approaches a circle and can ultimately be regarded as a circle.

[0021] Examples of suitable n-sided polygons include those whose cross-section is selected from the group consisting of triangles, rectangles, squares, pentagons, hexagons, heptagons, octagons, and any regular polygon having at least 9 sides. Preferably, the n-sided polygon is a regular n-sided polygon.

[0022] In general, the size of the duct, defined by its length and maximum inner width (or diameter), is not particularly limited. When determining the size of the duct, it is necessary to keep in mind that the length and maximum inner width of the duct affect pressure loss, which in turn affects the overall performance of the anemometer apparatus. In general, an increase in duct length leads to an increase in pressure loss, and at the same time, a decrease in diameter also leads to an increase in pressure loss. If the dimensions of the duct are known, the resulting pressure loss can be easily calculated using well-known equations such as the Darcy-Weisbach equation.

[0023] Generally, the maximum inner width of a duct is determined by the size of the gas inlet of the gas sampler. However, the maximum inner width R (also referred to herein as “diameter R”), which is the longest straight line that can be placed within the cross-section of the duct, is preferably at least 10 mm, preferably at least 20 mm, more preferably at least 30 mm, and most preferably at least 40 mm. The maximum inner width R or diameter R may be, for example, up to 100 mm, preferably up to 90 mm, more preferably up to 80 mm, even more preferably up to 70 mm, and most preferably up to 60 mm.

[0024] In a preferred example, the duct diameter R is 45 mm to 55 mm, particularly to allow calibration of gas or air samplers at low flow rates. Similarly, the length of the duct is not particularly limited. In any case, its length is determined by the distance D as defined herein.

[0025] Floral laminators are generally intended to help reduce turbulence in the inflow and passage of gas into a duct, enabling reproducible and reliable measurement of gas flow rates. Therefore, a floral laminator can also be described as a means of generating essentially laminar gas flow. A floral laminator consists of channels and walls, the walls separating the channels. Preferably, the floral laminator is a plate, more preferably a disk, comprising channels and walls, the walls separating the channels.

[0026] Preferably, the thickness (or height) H of the flora laminator is at least 5% (e.g., 5%, 6%, 7%, 8%, 9%, or 10%) of the distance D as defined herein, more preferably at least 7%, even more preferably at least 8%, even more preferably at least 9%, and most preferably at least 10%.

[0027] Preferably, the thickness (or height) of the flora laminator is 20% or less of the distance D as defined herein, more preferably 18% or less, even more preferably 16% or less, even more preferably 14% or less, and most preferably 12% or less.

[0028] In a preferred embodiment, the thickness H of the floral laminator is at least 5 mm, preferably at least 6 mm, more preferably at least 7 mm, even more preferably at least 8 mm, and most preferably at least 9 mm. There is no particular upper limit to the thickness H of the floral laminator, but for handling reasons, the thickness H of the floral laminator is preferably up to 50 mm or 40 mm, more preferably up to 30 mm, even more preferably up to 25 mm, even more preferably up to 20 mm, and most preferably up to 15 mm.

[0029] The other two dimensions of the flora laminator, namely the x and z dimensions when the thickness H is considered as the y direction (see Figure 1), are not particularly limited as long as the flora laminator is sufficient to cover the first open end of the duct.

[0030] The flora laminator has a porosity of at least 60%, preferably at least 65%, more preferably at least 70%, even more preferably at least 75%, and most preferably at least 80%. Generally, a higher porosity is preferred to minimize potential turbulence in the gas flow. This also allows for a shorter distance D.

[0031] Throughout this application, the term "porosity" is used to express the ratio of the channel (opening) area that allows for a continuous flow of gas across the flora laminator to the area of ​​the first open end of the duct.

[0032] For example, a plate-shaped flora laminator can be inserted into or installed on top of a duct. When inserted into or installed inside a duct, the dimensions of the flora laminator match the dimensions of the duct. For example, the diameter of the flora laminator is R. Alternatively, when installed on top of a duct, the dimensions of the flora laminator are set so that it protrudes from the duct by 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or more of the duct's diameter R.

[0033] The flow channels can be introduced into the flora laminator by any suitable method, for example, by drilling, in the shape of a plate. However, it has been found that flora laminators are preferably manufactured by (i) arranging tubes that form channels adjacent to each other, or (ii) directly manufacturing the flora laminator by extrusion molding, injection molding, or 3D printing. All of these methods are well known to those skilled in the field and do not need to be explained in detail.

[0034] The shape or cross-section of the channel is not particularly limited, but preferably it is the shape described above with respect to the duct. For clarity, it should be noted that the cross-sections of the channel and the duct may be the same or different.

[0035] The dimensions of the flow path can be easily adjusted to suit the specific conditions under which this anemometer device is used, particularly the flow rate.

[0036] For example, the maximum internal (opening) length of the channel may be at least 1.0 mm, preferably at least 2.0 mm, more preferably at least 3.0 mm, even more preferably at least 4.0 mm, and most preferably at least 5.0 mm.

[0037] For example, the maximum internal (opening) length of the channel is 10.0 mm at most, preferably 9.0 mm at most, more preferably 8.0 mm at most, and most preferably 7.0 mm at most.

[0038] The gas velocity sensor is placed in the duct at a distance D from the flora laminator, where D is the distance from the inner surface of the flora laminator, i.e., the surface facing the inside of the duct. There are no particular restrictions, but it is preferable that the distance D is not too long in order to avoid excessive pressure drops.

[0039] Preferably, the distance D is at least 100%, more preferably at least 120%, even more preferably at least 140%, even more preferably at least 160%, and most preferably at least 180% of the maximum inner width R of the duct.

[0040] Preferably, the distance D is 250% or less of the maximum inner width R of the duct, more preferably 230% or less, even more preferably 210% or less, and most preferably 190% or less.

[0041] In a preferred embodiment, the distance D is at least 40 mm, more preferably at least 50 mm, even more preferably at least 60 mm, even more preferably at least 70 mm, most preferably at least 80 mm, and preferably the distance D is up to 150 mm, more preferably up to 140 mm or 130 mm, even more preferably up to 120 mm, even more preferably up to 110 mm, most preferably up to 100 mm.

[0042] The anemometer device of the present invention preferably further includes an adapter positioned at the second open end ("outlet") of the duct, thereby enabling an airtight (but removable) connection to a gas sampler. Preferably, the adapter further includes a seal configured to achieve an airtight connection between the anemometer device and the gas sampler. Such an airtight connection can be achieved by providing the adapter with a seal (for example, in the form of an O-ring positioned in a groove of the adapter) which is pressed against a corresponding surface of the gas sampler.

[0043] By not permanently integrating the anemometer into the gas sampler, several advantages are available in this particular application. In particular, the anemometer does not interfere with the gas sampling process during operation, preventing a decrease in reproducibility, and a single anemometer can be used to calibrate multiple gas samplers.

[0044] This paper has shown that a thermal anemometer is the most suitable type of anemometer. Suitable thermal anemometers include so-called "hot-wire anemometers" or "heat flow meters."

[0045] In a hot-wire anemometer, a thin wire, such as a tungsten wire, is heated to a temperature higher than the ambient temperature, i.e., the temperature of the gas flowing inside the anemometer. The thin wire is then cooled by the gas flow; in other words, heat is transferred from the wire to the gas.

[0046] Since the electrical resistance of most metals depends on the temperature of the metal, the velocity of gas passing through a wire can be estimated from the change in the electrical resistance of the wire. This principle can be implemented, for example, in constant current anemometers, constant voltage anemometers, or constant temperature anemometers, where the electrical resistance is measured using Ohm's law.

[0047] Thermal flow meters measure the temperature of one element or heating element both upstream and downstream, or the temperature of one or more elements or heating elements positioned at a distance from each other in the direction of gas flow. Gas passing through the elements transfers heat downwind, increasing its temperature. The downwind temperature change is thought to correlate with the gas flow rate.

[0048] Such thermal anemometers typically include a probe that drives and / or controls, a general-purpose input / output (GIPO) board that receives the signal to acquire data, and a converter for digitizing the acquired data. Based on a conversion algorithm, this data is converted into gas flow rate by a processor. Such a processor may be part of the thermal anemometer or it may be separate from it.

[0049] Thermal anemometers are available from many manufacturers. One example of a commercially available thermal anemometer suitable for use with this anemometer system is the TSI Air Velocity Transducer Model 8465 from Shoreview, Minnesota, USA.

[0050] Due to the presence of the flora laminator, the anemometer apparatus described herein exhibits nonlinear drift. Therefore, in order to qualify as a calibration apparatus, the anemometer apparatus itself must be calibrated, which can be done using well-known methods. For example, calibration can be performed using a test stand equipped with sonic nozzles, each capable of generating a predetermined gas flow rate (e.g., one or more selected from the group consisting of 15 l / min, 30 l / min, 60 l / min, 90 l / min, 120 l / min, and 150 l / min).

[0051] First, the average of the raw measurements of the anemometer device installed on the test bench's sonic nozzle is calculated during the acquisition phase using the following acquisition parameters: filtering period (on transducer): 5 seconds, acquisition frequency: 2 Hz, acquisition period: 30 seconds. These discrete values ​​are used to determine the coefficients of the regression model used to adjust the system's measurements. In some cases, a power-law model may be preferable for such a regression model.

[0052] Therefore, the anemometer device (1) itself can be calibrated using a test stand equipped with an acoustic nozzle, and the calibration includes the following steps. (1) A step to calculate the average value of the raw data obtained during the acquisition phase; (2) Next, the step of determining the coefficients of the regression model (preferably a power model) based on the values ​​obtained in step (1).

[0053] The anemometers described herein are described below in an illustrative and non-limiting manner with reference to the drawings. Figure 1 shows the anemometer device (1) described herein, which includes a duct (2), a flora laminator (4, 4') having an inner surface (3a), a thermal anemometer (5), and an adapter (6) for connecting the anemometer device (1) to a gas sampler, with the flora laminator (4, 4') mounted on the duct (2).

[0054] Figure 2 also shows the anemometer device (1) described herein, which comprises a duct (2), a flora laminator (4, 4') having an inner surface (3a), a thermal anemometer (5), and an adapter (6) for connecting the anemometer device (1) to a gas sampler, but in contrast to the anemometer device (1) in Figure 1, the flora laminator (4, 4') is inserted into the duct (2).

[0055] Figure 3 shows a schematic example of a flora laminator (4) in the shape of a disc (4') with a hexagonal channel (7') separated by a wall (8). The illustrated example is particularly suitable for insertion into a duct, but it can also be installed on top of a duct, preferably with a wider edge, in which case the edge preferably does not contain grooves to minimize excess turbulence.

[0056] The anemometer device of the present invention is very suitable for accurately measuring low gas flow rates, such as a maximum of 28.3 l / min, preferably at least 1 l / min. Such flow rates are commonly used in gas samplers and air samplers. To obtain consistent results, it is desirable that the gas flow within the anemometer device be as laminar as possible.

[0057] Therefore, it is preferable that the anemometer device of the present invention be designed to minimize obstacles, bends, and gas outlets within the duct. In a particularly preferred embodiment, only a thermal anemometer enters the gas flow within the duct.

[0058] To determine the gas flow rate of the gas sampler, an anemometer device as described herein is provided, with its second open end ("outlet") attached to the gas inlet of the gas sampler. The gas flow rate can then be measured.

[0059] The anemometer device of the present invention is particularly preferred for the calibration of gas or air samplers. Therefore, the present invention also generally relates to a method for calibrating gas or air samplers, the method being: (a) A step of providing a gas sampler to be calibrated; (b) step of providing an anemometer device according to this specification; (c) the step of attaching the second open end of the anemometer device to the gas inlet of the gas sampler; and (d) Steps to calibrate the gas sampler Includes.

[0060] The actual calibration in step (d) of the method of the present invention can be performed by setting the gas flow rate of the gas sampler to a value determined by the gas sampler, or to a value determined by the anemometer device of the present invention, and then calibrating the device.

[0061] Therefore, step (d) in the gas sampler calibration method is the following step (d'-1) Step of setting the gas flow rate of the gas sampler to a desired value; (d'-2) A step of determining the actual gas flow rate using an anemometer; and (d'-3) This may include a step to calibrate the gas sampler.

[0062] Alternatively, step (d) of the gas sampler calibration method is the following steps: (d''-1) The step of increasing the gas flow rate of the gas sampler to a pre-selected actual gas flow rate measured by an anemometer; and (d''-2) Steps to calibrate the gas sampler It can include...

[0063] Calibration procedures typically involve comparing measurements obtained from the device under test (i.e., the gas sampler) with measurements obtained from the anemometer. This comparison will either reveal no significant error between the two instruments, or it will reveal a significant error requiring adjustments to reduce the error or deviation of the device under test to an acceptable level.

[0064] The anemometer described herein remarkably enables accurate and reliable calibration of the gas sampler even at low gas flow rates. Therefore, the actual gas flow rate is preferably up to 28.3 l / min, more preferably up to 25 l / min, even more preferably up to 20 l / min, and most preferably up to 15 l / min. Preferably, the actual gas flow rate is at least 1 l / min, more preferably at least 5 l / min, and most preferably at least 10 l / min.

[0065] In a particular embodiment, an anemometer device particularly suitable for low flow rates as defined above has a duct with a maximum inner width R of at least 45 mm and a maximum of 55 mm, a flora laminator with a thickness or height H of at least 8 mm and a maximum of 12 mm, a distance D of 80 mm or more and 100 mm or less, and a flora laminator with a porosity of 80% or more. The channel preferably has an internal (opening) length of at least 5 mm and a maximum of 7 mm, and / or may be, for example, hexagonal.

[0066] example The following examples illustrate the anemometer of the present invention without limiting it.

[0067] Example 1 A commercially available fan-type anemometer and a commercially available mass flow sensor were compared. Ten flow measurements were taken for each device, and the results are shown in Table 1 below. [Table 1] The significantly lower readings from commercially available mass flow sensors are due to much greater pressure loss. Therefore, this data clearly demonstrates that such anemometers are not suitable for use in combination with low-flow gas samplers.

[0068] Example 2 The anemometer device of the present invention (R=50mm, H=10mm, D=90mm, porosity=85%) was tested on a test stand equipped with a sonic nozzle at various gas flow rates. The results are shown in Table 2 below. Here, "set gas flow rate" is the gas flow rate of each sonic nozzle, "measured gas flow rate" is the gas flow rate measured using this anemometer device, and "error" is the error between the set gas flow rate and the measured gas flow rate, expressed as a percentage. [Table 2] This data clearly demonstrates that this anemometer device operates with extremely high accuracy and can therefore be used for calibrating gas samplers.

[0069] Example 3 The anemometer device of the present invention (R=50mm, H=10mm, D=90mm, porosity=85%) and a commercially available fan-type anemometer were compared in terms of pressure loss on a test stand equipped with an ultrasonic nozzle. The results are shown in Figure 4.

[0070] Therefore, generally speaking, the anemometer defined in this application has proven to be highly accurate in measuring gas flow rates, even at low flow rates of 15 l / min. This is also useful for calibrating gas samplers, particularly air samplers, used for cleanroom cleanliness control. At the same time, this anemometer has a very simple and user-friendly design, as well as a robust construction, making it portable and suitable for use by on-site service technicians.

[0071] This eliminates the need to send gas samplers to laboratories equipped with specialized facilities, allowing for on-site calibration. Sending them to a laboratory would require either managing without a gas sampler for a period of time, or purchasing at least one additional gas sampler to continue monitoring while the first one is being calibrated is unavailable.

[0072] Furthermore, it should be noted that the actual flow rate measured by this anemometer can be converted from liters per minute ("l / min") to standard liters per minute ("slpm") by combining it with the respective gas temperature and pressure sensors, which may be directly integrated into the anemometer or provided separately.

[0073] Furthermore, and this is particularly important given the increasing demand for traceability, this anemometer can easily digitize data, allowing it to be directly imported into, for example, a laboratory management system (LIMS).

Claims

1. (i) a duct (2) having a maximum inner width R, a first open end (3a), and a second open end (3b), for guiding gas from the first open end ("inlet") to the second open end ("outlet"); (ii) A floral laminator (4) covering the first open end (3a) of the duct (2); and (iii) A thermal anemometer (5) is placed inside the duct (2) at a distance D from the flora laminator (4). An anemometer device (1), including the anemometer device.

2. An anemometer device (1) according to claim 1, wherein the duct (2) has a cross-section selected from the group consisting of circular, elliptical, and polygonal shapes, preferably a cross-section selected from the group consisting of circular, elliptical, and regular n-gonal shapes where n is at least 3, and preferably the duct (2) has a circular cross-section.

3. The anemometer device (1) according to claim 1 or 2, wherein the duct (2) has a maximum inner width R of 60 mm, preferably 55 mm, and most preferably 50 mm.

4. The anemometer device (1) according to any one of claims 1 to 3, wherein the duct (2) has a maximum inner width R of at least 35 mm, preferably at least 40 mm, and most preferably at least 45 mm.

5. An anemometer device (1) according to any one of claims 1 to 4, wherein the flora laminator (4, 4') has a thickness (or height) H of at least 5%, preferably at least 6%, more preferably at least 7%, even more preferably at least 8%, even more preferably at least 9%, and most preferably at least 10% of the distance D.

6. An anemometer device (1) according to any one of claims 1 to 5, wherein the flora laminator (4, 4') has a thickness (or height) of up to 20%, preferably up to 18%, more preferably up to 16%, even more preferably up to 14%, and most preferably up to 12% of the distance D.

7. An anemometer device (1) according to any one of claims 1 to 6, wherein the flora laminator (4, 4') has a porosity of at least 70%, preferably at least 75%, and most preferably at least 80% of the total surface area of ​​the flora laminator (4, 4').

8. An anemometer device (1) according to any one of claims 1 to 7, wherein the distance D is at least 100%, preferably at least 120%, more preferably at least 140%, even more preferably at least 160%, and most preferably at least 180% of the maximum inner width R.

9. An anemometer device (1) according to any one of claims 1 to 8, wherein the distance D is 250% or less of the maximum inner width R, preferably 230% or less, more preferably 210% or less, and most preferably 190% or less.

10. An anemometer device (1) according to any one of claims 1 to 9, wherein the anemometer device (1) includes an adapter (6) positioned at a second open end (3b) of the duct, thereby enabling the anemometer device (1) to be airtightly connected to the gas sampler, and preferably the adapter (6) further includes a seal configured to achieve an airtight connection between the anemometer device (1) and the gas sampler.

11. A method for measuring the actual gas flow rate of a gas sampler, wherein the actual gas flow rate is a maximum of 28.3 l / min, the method comprising the steps of: providing a gas sampler; providing an anemometer device (1) according to any one of claims 1 to 10; attaching the second open end (3b) of the anemometer device (1) to the gas inlet of the air sampler; and determining the actual gas flow rate.

12. A method for calibrating a gas sampler, (a) Providing a gas sampler to be calibrated; (b) Providing an anemometer device (1) according to any one of claims 1 to 10; (c) The step of attaching the second open end (3b) of the anemometer device (1) to the gas inlet of the gas sampler; and (d) Steps to calibrate the gas sampler The method, including the method described above.

13. Step (d) is (d'-1) Step of setting the gas flow rate of the gas sampler to a desired value; (d'-2) A step of determining the actual gas flow rate using an anemometer; and (d'-3) Includes a step of calibrating the gas sampler, Alternatively, step (d) is (d''-1) The step of increasing the gas flow rate of the gas sampler to a pre-selected actual gas flow rate measured by an anemometer; and (d''-2) Steps to calibrate the gas sampler A method for calibrating a gas sampler according to claim 12, including the following:

14. A method for calibrating a gas sampler according to claim 12 or 13, wherein the actual flow rate is a maximum of 28.3 l / min, more preferably a maximum of 25 l / min, even more preferably a maximum of 20 l / min, and most preferably a maximum of 15 l / min.

15. A method for calibrating a gas sampler according to any one of claims 12 to 14, wherein the actual flow rate is at least 1 l / min, preferably at least 5 l / min.

16. The anemometer device (1) itself is calibrated using a test stand equipped with an acoustic nozzle, and the following: (1) A step of calculating the average value of the raw data obtained during the acquisition phase; (2) Next, the step of determining the coefficients of the regression model, preferably a power model, based on the values ​​obtained in step (1). A method for calibrating a gas sampler according to any one of claims 12 to 15, including the following:

Images