Flowmeter detection and distribution of

Abstract

A monitoring method implemented in a flow meter (1), the flow meter comprising: a measuring device (6) arranged to measure a flow rate of the fluid and a valve (12), the monitoring method comprising a preliminary phase comprising a step of acquiring a first flow rate measurement; and a detection phase, which is performed if the flow remains non-zero and is less than a predetermined first threshold for at least one predetermined duration, and which comprises the following steps:-verifying whether the valve is open and, if open, closing the valve; acquiring at least one second flow measurement; if the flow rate is zero, detecting a fluid leak.

Description

Technical Field

[0001] The present invention relates to the field of flow meters, and in particular to ultrasonic flow meters. Background Art

[0002] Ultrasonic flow meters very traditionally include a conduit in which the fluid circulates and an ultrasonic measuring device, which includes an upstream transducer (network side) and a downstream transducer (subscriber's installation side). Each transducer acts as an ultrasonic signal transmitter and receiver in turn. The upstream transducer therefore transmits an ultrasonic signal in the conduit, which is received by the downstream transducer after traveling a predefined path (with a fully controlled length) in the fluid. Subsequently, the downstream transducer itself transmits an ultrasonic signal, which is received by the upstream transducer after traveling the predefined path (in the other direction) in the fluid. Therefore, the ultrasonic measuring device evaluates the velocity of the fluid based on the transit time of the ultrasonic signal, and then evaluates the flow rate of the fluid based on the velocity of the fluid. Estimating the flow rate of the fluid makes it possible to evaluate the amount of fluid consumed and to bill for it.

[0003] Therefore, the working principle of ultrasonic measurement equipment is based on measuring the transit time of the ultrasonic signal between two transducers. The basic equation is as follows:

[0004] v = L / (t_AB - t_BA) (Formula 1),

[0005] Where v is the velocity of the fluid, L is the distance between the transducers, t_AB is the transit time between the upstream transducer and the downstream transducer, and t_BA is the transit time between the downstream transducer and the upstream transducer.

[0006] Q = A*v (Formula 2),

[0007] Where Q is the volume flow rate and A is the cross-sectional area of ​​the conduit.

[0008] However, in practice, it is observed that at zero flow, the transit time between the upstream and downstream transducers (t_AB) is not equal to the transit time between the downstream and upstream transducers (t_BA). This phenomenon is due to mechanical and electronic tolerances of the measurement chain integrated in the ultrasonic measurement device. This zero flow transit time difference is called "offset error" and will be referred to as "offset" in the rest of this document.

[0009] To avoid degrading the accuracy of the meter, it is necessary to calibrate the meter to zero flow to account for its offset.

[0010] Therefore, the speed is obtained by using:

[0011] V = L / (t_AB - t_BA - offset) (Equation 3),

[0012] exist Figure 1 In Figure 1, an example of measuring the zero flow offset of an ultrasonic water meter is shown before calibration (point P1) and after calibration (point P2). Before calibration, the offset was observed to be centered around 2L / h, which resembles a small trickle leak. The purpose of the offset calibration is to zero the curve to avoid any erroneous measurements.

[0013] This offset creates a very unique problem.

[0014] Being able to detect fluid leaks in facilities downstream of a flow meter is naturally very advantageous.

[0015] A method is known from the prior art which consists in detecting leaks by searching for the presence of a constant but non-zero flow rate. However, deviations of the ultrasonic measuring device or incorrectly calibrated electronic offsets can generate a false flow rate which can persist indefinitely. The value of this flow rate can vary depending on the water temperature.

[0016] It is therefore difficult to distinguish between an incorrectly calibrated offset and a real leak, and one can never be sure that the actual flow is actually zero.

[0017] The present invention aims to detect these two events in a flow meter by correctly distinguishing between an actual leak or an offset problem downstream of the flow meter. Summary of the invention

[0018] In order to achieve this purpose, a monitoring method implemented in a flow meter is proposed, the flow meter comprising:

[0019] - a conduit in which a fluid circulates;

[0020] - a measuring device arranged to measure the flow rate of the fluid;

[0021] - a valve located upstream of said measuring device;

[0022] - Processing unit;

[0023] The monitoring method is implemented in the processing unit and comprises a preliminary phase comprising the steps of obtaining a first flow measurement;

[0024] The monitoring method further comprises a detection phase, which is performed if the flow rate remains non-zero and less than a predetermined first threshold for at least one predetermined duration, and the detection phase comprises the following steps:

[0025] - verifying whether the valve is open and, if so, closing the valve;

[0026] - obtaining at least one second flow measurement;

[0027] - If the flow rate is zero, a fluid leak is detected.

[0028] When flow remains non-zero and low for a relatively long duration, this means there may be a leak in the facility downstream of the flow meter, or an offset problem with the measuring device. Therefore, closing the valve makes it possible to produce zero flow (of course), making it possible to detect and distinguish between these two events.

[0029] Additionally, a monitoring method such as described above is proposed, wherein if the flow rate is not zero, then after obtaining the at least one second flow rate measurement, the detection phase comprises the following steps:

[0030] - verifying at least one first condition, said at least one first condition comprising a first main condition, said first main condition being that said flow rate is constant;

[0031] - If said at least one first condition is verified, an offset problem in said measuring device is detected.

[0032] In addition, a monitoring method such as the above is proposed, wherein the at least one first condition further comprises a first secondary condition, and the first secondary condition is that the flow rate is less than a predetermined second threshold value.

[0033] Additionally, a monitoring method such as described above is proposed, wherein if the flow rate is not zero, then after obtaining the at least one second flow rate measurement, the detection phase comprises the following steps:

[0034] - verifying at least one second condition, said at least one second condition comprising a second main condition, said second main condition being that said flow rate is variable;

[0035] - If said at least one second condition is verified, an operating defect of said valve is detected.

[0036] In addition, a monitoring method such as the one described above is proposed, wherein the at least one second condition further includes a second secondary condition, and the second secondary condition is that the flow rate is greater than a predetermined third threshold value.

[0037] In addition, a monitoring method such as the above is proposed, wherein the detection phase includes a step of calculating the standard deviation of a predefined number of second flow measurements, the first main condition being verified when the standard deviation is smaller than a predetermined difference threshold, and the second main condition being verified when the standard deviation is larger than the predetermined difference threshold.

[0038] Furthermore, a monitoring method such as described above is proposed, wherein the detection phase comprises, after the verification step of whether the valve is open, detecting an offset problem in the measuring device in case the valve is closed.

[0039] In addition, a monitoring method such as the above is proposed, wherein the preliminary phase further comprises a step of obtaining a measurement of the temperature of the fluid, and the monitoring method further comprises a step of repeating the detection phase whenever the temperature of the fluid deviates from a previous detection phase by at least one predefined temperature threshold.

[0040] Additionally, a monitoring method such as that described above is proposed, wherein the detection phase is implemented at night.

[0041] Furthermore, a monitoring method such as described above is proposed, further comprising a step of individually accounting for the water consumption of the installation from the moment a leakage or a deviation problem or an operating defect of said valve is detected.

[0042] In addition, a flow meter is proposed, comprising

[0043] - a conduit in which a fluid circulates;

[0044] - a measuring device arranged to measure the flow rate of the fluid;

[0045] - a valve located upstream of said measuring device;

[0046] - A processing unit, in which a monitoring method such as described above is performed.

[0047] Furthermore, a flow meter such as described above is proposed, wherein the measuring device is an ultrasonic measuring device.

[0048] Furthermore, a computer program is proposed, comprising instructions for causing a processing unit such as described above to perform the steps of a monitoring method such as described above.

[0049] In addition, there is proposed a computer-readable recording medium having recorded thereon a computer program such as that described above.

[0050] The present invention will best be understood from the following description of specific non-limiting embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Reference will be made to the accompanying drawings, in which:

[0052] [ Figure 1 ] Figure 1 A diagram showing a measurement point of zero flow electronic noise before calibration and a measurement point of the noise after calibration;

[0053] [ Figure 2] Figure 2 Indicates ultrasonic water meter;

[0054] [ Figure 3 ] Figure 3 Indicates the steps of the monitoring method. DETAILED DESCRIPTION

[0055] refer to Figure 2 , the invention is implemented in an ultrasonic flow meter 1. In this case, the meter 1 is a water meter, which is used to measure the water consumption of a subscriber's installation 2. The water is supplied to the installation 2 by a water distribution network 3.

[0056] The meter 1 comprises a conduit 4 in which circulates water supplied by the network 3 to the installation 2. The water circulates in the conduit 4 from upstream to downstream, as indicated by the direction of the arrow F. In this case, "upstream" means from the network 3 side, and "downstream" means from the installation 2 side.

[0057] The meter 1 comprises a processing unit 5 (electronics and software). For example, the processing unit 5 comprises at least one processing component 5a, which is, for example, a "general purpose" processor, a processor specialized in processing signals (or a DSP (digital signal processor)), a microcontroller, or a programmable logic circuit, such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). The processing circuit 5 also comprises one or more memories 5b connected to or integrated into the processing component 5a. At least one of these memories 5b forms a computer-readable recording medium on which is recorded at least one computer program, which at least one computer program comprises instructions for causing the processing component 5a to execute at least some steps of the monitoring method to be described below.

[0058] The meter 1 also comprises an ultrasonic measuring device 6 . The ultrasonic measuring device 6 is used to measure the flow rate of water supplied by the network 3 to the installation 2 .

[0059] The ultrasonic measuring device 6 comprises an upstream transducer 7a and a downstream transducer 7b. The ultrasonic measuring device 6 further comprises a processing module 9 connected to the upstream transducer 7a and the downstream transducer 7b. In this case, the processing module 9 is implemented in the processing unit 5.

[0060] The upstream transducer 7a and the downstream transducer 7b are advantageously (but not necessarily) paired. In this case, the upstream transducer 7a and the downstream transducer 7b are piezoelectric transducers. Each transducer 7a, 7b acts as an ultrasonic signal transmitter and receiver in turn.

[0061] The processing module 9 generates an excitation electrical signal Se and provides it to the transmitter. The transmitter thus generates an ultrasonic signal Su. After the ultrasonic signal travels a predefined path in the fluid, the receiver receives the ultrasonic signal and the processing module 9 measures the transit time.

[0062] In this case, the predefined path is a direct path (parallel to the longitudinal axis of the catheter 4 (eg Figure 1 The predefined path may also be an indirect path: the ultrasound signal is thus reflected by the inner wall of the catheter (optionally by a reflector itself located on this inner wall).

[0063] The predefined path has a length L, which is known very clearly.

[0064] Thus, the upstream transducer 7a first transmits an ultrasonic signal which is received by the downstream transducer 7b. The processing module 9 measures the transit time between the upstream transducer and the downstream transducer.

[0065] Next, the downstream transducer 7b transmits an ultrasonic signal which is received by the upstream transducer 7a. The processing module 9 measures the transit time between the downstream transducer and the upstream transducer.

[0066] The processing module 9 calculates the speed of the water flow from these transit times and subsequently calculates the water flow rate from this speed.

[0067] The meter 1 also comprises a valve 12 which makes it possible to let water pass or to cut off the water flow. The valve 12 is therefore a two-position valve.

[0068] The valve 12 is a motorized (electromechanical) valve: it is a solenoid valve. The valve 12 comprises a movable member extending in the conduit 4. In this case, the valve 12 is a ball valve, and the movable member is therefore a ball. Thus, the angular position of the ball can be controlled to cut off the flow or to let water pass.

[0069] It should be noted that the valve 12 can also be a multi-position valve, which makes it possible to regulate, limit or cut off the water flow. In this case, the valve 12 is not only dedicated to the implementation of the monitoring method described in this case, but can also perform another function, such as enabling the water distributor and / or network manager to cut off or limit the water flow in the event of arrears.

[0070] A valve 12 is positioned along the length of the catheter 4 upstream of the two transducers 7a, 7b.

[0071] The meter 1 also comprises a temperature sensor 14 which measures the temperature of the water in the meter 1 .

[0072] The meter 1 additionally comprises a communication module 15 which enables any type of communication, for example, communication via a cellular network of the 2G, 3G, 4G, Cat-M or NB-IOT type, communication according to the LoRa protocol, the W-Mbus protocol, radio communication according to the Wize standard with an operating frequency of 169 MHz, etc.

[0073] The principle of the present invention will now be described.

[0074] If the valve 12 is open and the flow meter 1 measures a non-zero flow for a relatively long duration (typically several hours), there are three options:

[0075] There is indeed a leak downstream of meter 1, so the leak either occurs in the subscriber's facility 2 or at the interface between the downstream of meter 1 and facility 2 (for example, if meter 1 is connected incorrectly);

[0076] or the measuring device 6 has an offset problem (incorrectly calibrated offset or a deviation of the offset over time and / or temperature);

[0077] Or the valve 12 has an operational defect.

[0078] The monitoring method first comprises a preliminary phase, during which the processing unit 5 acquires a first flow measurement.

[0079] If during the preliminary phase the flow rate remains non-zero and below a predetermined first threshold for at least one predetermined duration, the processing unit 5 starts a detection phase.

[0080] The predetermined first threshold is, for example, equal to 3 L / h or 5 L / h. The predetermined duration is, for example, equal to 1 hour or 2 hours.

[0081] During the detection phase, the processing unit 5 first verifies whether the valve 12 is actually open.

[0082] If the valve 12 is closed, the processing unit 5 detects an offset problem in the measuring device 6. In fact, the measured flow must be zero (since the actual flow is practically zero, the valve 12 is closed).

[0083] If the valve 12 is actually open, the processing unit 5 closes the valve 12 .

[0084] The processing unit 5 acquires at least one second flow measurement (in this case several second flow measurements).

[0085] If the flow is zero, the processing unit 5 has therefore detected a water leak. By closing the valve 12, a flow of practically zero has been created. If the measuring device 6 correctly measures this zero flow, this means that there is no offset problem and no problem with the valve 12.

[0086] However, after obtaining at least one second flow measurement, if the flow is not zero, the processing unit 5 performs the following operations:

[0087] - verifying at least one first condition, the at least one first condition comprising a first main condition that the flow rate is constant;

[0088] If the at least one first condition is verified, an offset problem in the measuring device 6 is detected.

[0089] In this case, the at least one first condition further includes a first secondary condition, and the first secondary condition is that the flow rate is less than a predetermined second threshold value.

[0090] In this case, the predetermined second threshold value is equal to 5 L / h.

[0091] Indeed, if the measured flow is not zero, but constant, since a flow which is effectively zero has been produced, this means that the measuring device 6 is malfunctioning, and more specifically, that there is an offset problem in the measuring device 6 .

[0092] After obtaining at least one second flow measurement, if the flow is not zero, the processing unit 5 performs the following operations:

[0093] verifying at least one second condition, the at least one second condition comprising a second primary condition, the second primary condition being that the flow rate is variable;

[0094] If the at least one second condition is verified, an operating defect of the valve 12 is detected.

[0095] In this case, the at least one second condition further includes a second secondary condition, and the second secondary condition is that the flow rate is greater than a predetermined third threshold.

[0096] In this case, the predetermined third threshold value is equal to 10 L / h.

[0097] Indeed, if the measured flow is not zero, but is variable, this means that the valve 12 is malfunctioning, since a flow which is effectively zero has occurred.

[0098] After acquiring at least one second flow measurement, if the flow is not zero, the processing unit 5 therefore verifies whether the flow is constant (first main condition) or variable (second main condition).

[0099] To this end, the processing unit 5 calculates the standard deviation of a predefined number of second flow measurements, the first main condition being verified when the standard deviation is smaller than (in this case smaller than or equal to) a predetermined difference threshold, and the second main condition being verified when the standard deviation is greater than (in this case strictly greater than) the predetermined difference threshold.

[0100] The predefined number is equal to ten, for example.

[0101] The predetermined difference threshold is, for example, equal to 1 L / h.

[0102] Now, refer to Figure 3 Specific embodiments of the monitoring method are described.

[0103] The method starts at step E0.

[0104] The processing unit 5 implements a preliminary phase and acquires a first flow measurement.

[0105] The processing unit 5 compares the flow rate with a predetermined first threshold value S1: step E1.

[0106] S1 is equal to 3 L / h or 5 L / h, for example.

[0107] When the flow rate is greater (in this case strictly greater) than S1 , the method loops through step E0 and then through step E1 .

[0108] When the flow rate becomes less than (in this case less than or equal to) S1 , while being non-zero, the processing unit 5 starts a chronometer: step E2 .

[0109] The processing unit 5 verifies whether the flow rate remains non-zero and less than a predetermined first threshold S1 for at least one predetermined duration D (in this case equal to, for example, 1 hour or 2 hours): step E3.

[0110] If this is not the case, the method returns to step E0.

[0111] If this is the case, the detection phase begins. The method moves to step E4. The processing unit 5 verifies whether the valve 12 is open.

[0112] If the valve 12 is closed, the processing unit 5 detects an offset problem in the measuring device 6 : step 5 .

[0113] The processing unit 5 generates an alarm message indicating the deviation problem: step E6.

[0114] In step E4 , if valve 12 is open, processing unit 5 closes valve 12 : step E7 .

[0115] The processing unit 5 verifies whether the flow rate is zero: step E8.

[0116] If this is the case, a "real" leak is detected (step E9) and it generates an alarm message indicating the presence of this leak: step E10.

[0117] If this is not the case, the processing unit 5 verifies the first and second main conditions (in this embodiment, at least one first condition comprises only the first main condition, and at least one second condition comprises only the second main condition).

[0118] The verification of the first and second main conditions firstly consists in measuring the standard deviation σ of a predefined number (in this case equal to 10 for example) of second flow measurements: step E11 .

[0119] The processing unit 5 verifies whether the standard deviation σ is greater than (in this case strictly greater than) a predetermined difference threshold M: step E12. The predetermined difference threshold is for example equal to 1 L / h.

[0120] If this is not the case, the method moves to step E5: the processing unit 5 detects an offset problem in the measuring device 6. The processing unit 5 generates an alarm message indicating the offset problem: step E6.

[0121] If this is the case, the processing unit 5 detects an operating defect of the valve 12: step E13. The processing unit 5 generates an alarm message indicating this problem related to the valve 12: step E14.

[0122] In steps E6, E10 and E14, an alarm message is returned to the water distributor and / or the network manager via the communication module 15. The alarm message may also be transmitted to the user. The alarm may be displayed on the screen of the meter 1. It is advisable to repeat the detection phase for different water temperatures. In fact, the flow meter 1 may not measure any flow rate that is non-zero and less than a predetermined first threshold at one or more given temperatures, but may measure such a flow rate at one or other temperature.

[0123] This is observed, for example, in the case of a deviation of the offset depending on the temperature. For example, the offset may be well calibrated at 20°C instead of 40°C, so that the flow meter 1 does not measure any non-zero flow at 20°C (e.g. with the valve 12 closed), while at temperatures close to 40°C it measures an erroneous flow.

[0124] Therefore, during the preliminary phase, and therefore in Figure 2 In step E0 of , the processing unit 5 also obtains a measurement of the water temperature generated by the temperature sensor 14 .

[0125] In step E5 , the excursion problem is associated with the fluid temperature; therefore, the returned alarm message also includes said temperature.

[0126] The detection phase is repeated each time the temperature of the fluid deviates from the previous detection phase by at least one predefined temperature threshold.

[0127] The predefined temperature threshold is for example equal to 5° C. (this may be an increase or decrease in temperature).

[0128] Optionally, the processing unit 5 separately accounts for the water consumption of the installation 2 from the moment of detecting a leak or a deviation problem or an operating defect of the valve 12. Thus, the overall total consumption of the installation 2 is distinguished from the consumption of the installation 2 from the moment of detecting the anomaly.

[0129] This enables the water distributor and / or network manager and / or user to take steps to correct and optionally compensate for billing problems caused by the anomaly.

[0130] It should be noted that it is advantageous to carry out the detection phase at night. The detection phase does require that the valve 12 be closed for a moment, which cuts off the water flow.

[0131] It is also advantageous to carry out the second measurement at a high frequency (for example: several measurements per second), which makes it possible to limit the closing time of the valve 12 .

[0132] The advantages provided by the present invention are as follows.

[0133] The present invention makes it possible to continuously and accurately monitor the flow rate and temperature of a fluid.

[0134] It enables the rapid identification of potential problems such as leaks, electronic offset issues and valve-related problems. It also therefore enables quick and effective intervention to correct the problem.

[0135] The invention minimizes disruption to the user due to limited intervention in the valve.

[0136] The meter actively transmits notification of detected problems to the water distributor and / or network manager and / or user by displaying an alarm message on the screen of the water meter 1 or sending an alarm message by the communication module 15 .

[0137] As can be seen, it is possible to individually account for the amount of water consumed in the event that a problem is identified, thereby enabling better management of the customer's overall consumption.

[0138] Thus, the present invention provides an effective and proactive solution for monitoring and managing issues related to flow and temperature of fluids while maintaining an optimal user experience for the user (end customer).

[0139] Of course, the invention is not limited to the embodiments described but encompasses any variant coming within the field of the invention such as defined in the claims.

[0140] The invention naturally applies regardless of the positioning and configuration of the upstream and downstream transducers.The ultrasonic signal may be emitted at any angular orientation relative to the longitudinal axis of the catheter.

[0141] The predefined path between the transducers is not necessarily a direct path. For example, an ultrasonic signal transmitted and received by a transducer in a conduit may be reflected by a reflector (eg, by a mirror oriented at 45°). The flow meter is not necessarily an ultrasonic flow meter.

[0142] The present invention is not only applicable to water meters, but also to any meter for any fluid (natural gas, oil, etc.).

[0143] The valve does not have to be a ball valve. Any type of valve (e.g., a slide valve) can be used to cut off the flow.

Claims

1. A monitoring method implemented in a flow meter (1), the flow meter (1) include: - a conduit (4) in which a fluid circulates; - a measuring device (6) arranged to measure the flow rate of the fluid; - a valve (12) located upstream of the measuring device; - a processing unit (5); The monitoring method is implemented in the processing unit and comprises a preliminary phase comprising the steps of obtaining a first flow measurement; The monitoring method further comprises a detection phase, which is performed if the flow rate remains non-zero and less than a predetermined first threshold value (S1) for at least a predetermined duration (D), and comprises the following steps: - verifying whether the valve (12) is open and, if so, closing the valve; - obtaining at least one second flow measurement; - If the flow rate is zero, a fluid leak is detected.

2. The monitoring method of claim 1, wherein if the flow rate is not zero, then after obtaining the at least one second flow rate measurement, the detection phase The following steps are involved: - verifying at least one first condition, said at least one first condition comprising a first main condition, said first main condition being that said flow rate is constant; - If the at least one first condition is verified, an offset problem in the measuring device (6) is detected.

3. The monitoring method as claimed in claim 2, wherein the at least one first condition further comprises a first secondary condition, wherein the first secondary condition is that the flow rate is less than a predetermined second threshold value.

4. A monitoring method as claimed in any one of the preceding claims, wherein if the flow rate is not zero, then after obtaining the at least one second flow rate measurement, the detection phase The following steps are involved: - verifying at least one second condition, said at least one second condition comprising a second main condition, said second main condition being that said flow rate is variable; - If said at least one second condition is verified, an operating defect of said valve (12) is detected.

5. The monitoring method according to claim 4, wherein the at least one second condition further comprises a second secondary condition, the second secondary condition being that the flow rate is greater than a predetermined third threshold value.

6. A monitoring method as described in claims 2 and 4, wherein the detection phase includes a step of calculating the standard deviation of a predefined number of second flow measurements, the first main condition being verified when the standard deviation is less than a predetermined difference threshold (M), and the second main condition being verified when the standard deviation is greater than the predetermined difference threshold.

7. A monitoring method according to any one of the preceding claims, wherein the detection phase comprises, after the verification step of whether the valve (12) is open, detecting an offset problem in the measuring device (6) when the valve is closed.

8. A monitoring method as claimed in any one of the preceding claims, wherein the preliminary phase further comprises the step of obtaining a measurement of the temperature of the fluid, the monitoring method further comprising the step of repeating the detection phase each time the temperature of the fluid deviates from a previous detection phase by at least one predefined temperature threshold.

9. The monitoring method according to any one of the preceding claims, wherein the detection phase is carried out at night.

10. Monitoring method according to any of the preceding claims, further comprising the step of individually accounting for the water consumption of the installation (2) from the moment of detection of a leakage or a deviation problem or an operating defect of the valve (12).

11. A flow meter (1), include: - a conduit (4) in which a fluid can circulate; - a measuring device (6) arranged to measure the flow rate of the fluid; - a valve (12) located upstream of the measuring device; - A processing unit (5) in which a monitoring method as claimed in any of the preceding claims is implemented.

12. The flow meter of claim 11, wherein the measuring device is an ultrasonic measuring device.

13. A computer-readable recording medium storing a computer program, the computer program comprising instructions for causing a processing unit (5) of a flow meter (1) according to any one of claims 11 or 12 to execute the steps of the monitoring method according to any one of claims 1 to 10.

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