A method for flow accumulation calibration of flow meters in small volumes

Abstract

This invention relates to the field of vacuum measurement technology. A method for calibrating a small volume of flow accumulation in a flowmeter is disclosed, comprising: online volume measurement of a standard volume chamber of the flowmeter, the flowmeter including a standard volume chamber, a vacuum flow guide orifice, an inflation module, and a molecular pump assembly, the vacuum flow guide orifice, the inflation module, and the molecular pump assembly being connected to the standard volume chamber respectively; the method comprising: responding to a test command, determining a target measurement mode, the target measurement mode including a first measurement mode and a second measurement mode; according to the target measurement mode, controlling the molecular pump assembly to evacuate the standard volume chamber, and then controlling the inflation module to inflate the standard volume chamber with gas, obtaining the inflation volume and inflation pressure difference; determining the volume of the standard volume chamber based on the inflation volume and inflation pressure difference. This application eliminates the need to load, unload, and send the standard volume chamber for testing, enabling on-site volume measurement of a standard volume susceptible to external factors.

Description

Technical Field

[0001] This invention relates to the field of vacuum measurement technology, and in particular to a method for calibrating a small volume of flow accumulation in a flowmeter. Background Technology

[0002] In the field of vacuum technology, there are two methods for volume calibration. The first is the vacuum expansion method, which expands the gas in a container of known volume into an unknown volume and measures and calibrates the volume of the unknown container by measuring the pressure change before and after this operation. The second is called the standard volume bar embedding method, which places a calibrated standard volume bar into a cavity of unknown volume and calculates the volume of the container being measured by comparing the results before and after the operation.

[0003] However, both methods have drawbacks. First, as a standard quantity whose accuracy is easily affected by external factors, volume, a fundamental physical parameter, is susceptible to changes caused by temperature, impact, vibration, and other factors. Unforeseen changes can occur during transportation from the factory to the usage scenario, and the usage scenario often lacks laboratory calibration conditions. This results in the standard volume of the equipment remaining in an inaccurate state during use, affecting the reliability and accuracy of the equipment. Second, for already assembled instruments, there are no conditions for self-calibration. Disassembling components and recalibrating the volume using the two methods mentioned above could potentially disrupt the already calibrated working state of other related instruments.

[0004] Therefore, there is a need to provide a method for online volume measurement of standard volumes. Summary of the Invention

[0005] In view of this, the present invention provides a method for calibrating a small volume of flow accumulation in a flow meter.

[0006] Specifically, the following technical solutions are included: This application provides a method for calibrating the flow accumulation of a flow meter into a small volume, used for online volume measurement of the standard volume chamber of the flow meter. The flow meter includes a standard volume chamber, a vacuum flow guide orifice, an inflation module, and a molecular pump assembly, wherein the vacuum flow guide orifice, the inflation module, and the molecular pump assembly are respectively connected to the standard volume chamber. The method includes: In response to a test command, a target measurement mode is determined, the target measurement mode including a first measurement mode and a second measurement mode; According to the target measurement mode, after controlling the molecular pump group to evacuate the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas to obtain the gas filling volume and gas filling pressure difference; The volume of the standard volume chamber is determined based on the inflation volume and the inflation pressure difference.

[0007] For example, when the target measurement mode is the first measurement mode, after the molecular pump group is controlled to perform a first vacuuming of the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas for the first time to obtain a first gas filling amount and a first gas filling pressure difference; the volume of the standard volume chamber is determined based on the first gas filling amount and the first gas filling pressure difference.

[0008] For example, when the target measurement mode is the second measurement mode, after controlling the molecular pump group to perform a first vacuuming of the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas for the first time to obtain a first gas filling volume and a first gas filling pressure difference; after controlling the molecular pump group to perform a second vacuuming of the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas for the second time to obtain a second gas filling volume and a second gas filling pressure difference; the volume of the standard volume chamber is determined based on the first gas filling volume, the second gas filling volume, the first gas filling pressure difference, and the second gas filling pressure difference.

[0009] For example, after the molecular pump group performs the first vacuuming of the standard volume chamber, the pressure inside the standard volume chamber is the first pressure; after the inflation module inflates the standard volume chamber for the first time, the pressure inside the standard volume chamber is the second pressure; and the first inflation pressure difference is obtained based on the first pressure and the second pressure.

[0010] For example, the ratio of the second pressure to the first pressure is greater than a first preset threshold.

[0011] For example, after the molecular pump group performs a second vacuuming of the standard volume chamber, the pressure inside the standard volume chamber is the third pressure; after the inflation module performs a second inflation of the standard volume chamber, the pressure inside the standard volume chamber is the fourth pressure; and the second inflation pressure difference is obtained based on the third pressure and the fourth pressure.

[0012] For example, the ratio of the fourth pressure to the third pressure is greater than a second preset threshold.

[0013] For example, when the target measurement mode is the first measurement mode, the volume of the standard volume chamber is determined based on the ratio of the first inflation volume to the first inflation pressure difference.

[0014] For example, when the target measurement mode is the second measurement mode, the inflation volume difference between the first inflation volume and the second inflation volume, and the inflation pressure difference between the second inflation pressure difference and the first inflation pressure difference are calculated, and the volume of the standard volume chamber is determined according to the ratio of the inflation volume difference and the inflation pressure difference.

[0015] For example, the standard volume chamber is equipped with a vacuum detection element for measuring the pressure inside the standard volume chamber.

[0016] The beneficial effects of the technical solution provided by this invention include at least the following: This application couples the vacuum flow guide orifice, the gas filling module, and the molecular pump assembly to the standard volume chamber, eliminating the need to assemble, disassemble, and send the standard volume chamber for testing. This allows for on-site measurement of the standard volume, which is susceptible to external factors, improving the flow meter's operational quality and maximizing its reliability and accuracy in field operation. This application can be used to measure the standard volume chamber inside flow meters that operate continuously for extended periods and cannot be shut down. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a flow meter structure for online volume measurement based on molecular conductance, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the flow structure of an online volume measurement method based on molecular conductivity according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the flow structure of the first measurement mode according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the flow structure of the second measurement mode according to an embodiment of the present invention.

[0019] The reference numerals in the figure are respectively: 1. Standard volume chamber; 2. Vacuum detection component; 3. Gas filling module; 4. First vacuum valve; 5. Second vacuum valve; 6. Third vacuum valve; 7. Vacuum flow guide orifice; 8. Molecular pump assembly.

[0020] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Before providing a further detailed description of the embodiments of the present invention, the directional terms used in the embodiments of the present invention, such as "upper part," "lower part," and "side part," are used to refer to... Figure 1 The orientation shown is a reference and does not limit the scope of protection of this invention.

[0023] To make the technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, this embodiment provides a flow meter, which includes a standard volume chamber 1, a vacuum flow guide orifice 7, an inflation module 3, and a molecular pump assembly 8. The vacuum flow guide orifice 7, the inflation module 3, and the molecular pump assembly 8 are respectively connected to the standard volume chamber 1. A vacuum detection element 2 is provided on the standard volume chamber 1 for measuring the pressure inside the standard volume chamber 1.

[0025] Specifically, such as Figure 1 As shown, the inflation module 3 is connected to the standard volume chamber 1 via a first vacuum valve, the molecular pump group 8 is connected to the standard volume chamber 1 via a second vacuum valve, and the vacuum flow guide orifice 7 is connected to the standard volume chamber 1 via a third vacuum valve.

[0026] Specifically, such as Figure 1 As shown, the volume V1 of the standard volume chamber 1 is unknown and is to be measured. The gas filling module 3 is used to fill the standard volume chamber 1 with gas at a standard flow rate. The gas filling module 3 can be a high-flow-rate commercial flow meter, whose gas flow rate Q is pre-measured by a metrology unit, and the filling time t can be recorded by the commercial flow meter's accompanying software. The molecular pump assembly 8 is used to extract gas from the standard volume chamber 1. The vacuum detection element 2 is a vacuum gauge used to determine the pressure value of the standard volume chamber 1. When the flow meter is working normally, the vacuum flow guide orifice 7 is used to draw a small gas flow rate from the standard volume chamber 1.

[0027] This application uses a molecular pump group 8 and an inflation module 3 to evacuate and inflate the standard volume chamber 1, thereby controlling the pressure in the standard volume chamber 1 and enabling online recalibration of the standard volume in the assembled flow meter.

[0028] like Figure 2As shown, this embodiment provides a method for calibrating the flow accumulation of a flow meter using a small volume, for online volume measurement and calibration of the standard volume chamber 1 of the flow meter. The method includes: S1: In response to the test command, determine the target measurement mode, which includes a first measurement mode and a second measurement mode.

[0029] In this embodiment, the measurement command can be triggered manually or automatically by the control program.

[0030] In this embodiment, the first measurement mode is a rapid measurement mode, and the second measurement mode is a precise measurement mode. The rapid measurement mode is suitable for application scenarios with limited time. The core of the precise measurement mode is to perform two measurements under different conditions, and eliminate uncertain interference caused by equipment factors such as temperature and temperature drift of the measuring instrument itself in the actual measurement based on the two measurement results, thereby improving measurement accuracy. It is suitable for scenarios that require precise measurement results.

[0031] S2: According to the target measurement mode, after controlling the molecular pump group 8 to evacuate the standard volume chamber 1, control the gas filling module 3 to fill the standard volume chamber 1 with gas, and obtain the gas filling volume and gas filling pressure difference.

[0032] S3: Determine the volume of standard volume chamber 1 based on the inflation volume and inflation pressure difference.

[0033] This application uses a molecular pump group 8 and an inflation module 3 to evacuate and inflate the standard volume chamber 1, thereby controlling the pressure in the standard volume chamber 1 and enabling online recalibration of the standard volume in the assembled flow meter.

[0034] In one embodiment, when the target measurement mode is the first measurement mode, step S2 includes: controlling the molecular pump group 8 to perform a first vacuuming of the standard volume chamber 1, and then controlling the gas filling module 3 to fill the standard volume chamber 1 with gas for the first time, obtaining a first gas filling amount and a first gas filling pressure difference; step S3 includes: determining the volume of the standard volume chamber 1 based on the first gas filling amount and the first gas filling pressure difference. The first measurement mode enables the measurement of the volume of the standard volume chamber 1 within a finite time.

[0035] Specifically, when the target measurement mode is the first measurement mode, the volume of the standard volume chamber 1 is determined based on the ratio of the first inflation volume to the first inflation pressure difference.

[0036] For details, please refer to Figure 1 When the target measurement mode is the first measurement mode, the pressure inside the standard volume chamber 1 after the molecular pump group 8 performs the first vacuuming is the first pressure. After the gas filling module 3 fills the standard volume chamber 1 with gas for the first time, the pressure inside the standard volume chamber 1 is the second pressure. The first gas filling pressure difference is obtained based on the first pressure and the second pressure.

[0037] Specifically, such as Figure 1 and Figure 3 As shown, when the target measurement mode is the first measurement mode, the specific steps include: S101: Control the first vacuum valve and the third vacuum valve to close, and the second vacuum valve and the molecular pump group 8 to open. Through the molecular pump group 8, the standard volume chamber 1 and all connecting pipes connected to it are evacuated to a vacuum state; close the second vacuum valve 5 to complete the first evacuation of the standard volume chamber 1 by the molecular pump group 8, and monitor the pressure value in the standard volume chamber 1 at this moment through the vacuum measuring device, that is, the first pressure is P1. S102: Open the first vacuum valve 4, keep the second vacuum valve 5 and the third vacuum valve 6 closed, use the gas filling module 3 to fill the standard volume chamber 1 in the vacuum state with the first standard gas flow rate Q1 within the first gas filling time t1, and complete the first gas filling of the standard volume chamber 1 by the gas filling module 3. Close the first vacuum valve 4 to isolate the gas filling module 3 and the standard volume chamber 1. After the pressure stabilizes, record the pressure value in the standard volume chamber 1 at this moment through the vacuum measuring device, that is, the second pressure P2. S103: The first inflation volume is determined by the first inflation time t1 and the first standard gas flow rate Q1, the first inflation pressure difference is determined by the first pressure P1 and the second pressure P2, and the volume V1 of the standard volume chamber 1 is determined according to the first inflation volume and the first inflation pressure difference.

[0038] Specifically, when the target measurement mode is the first measurement mode, the volume V1 of the standard volume chamber 1 is determined by the following formula:

[0039] In one embodiment, when the target measurement mode is the second measurement mode, step S2 includes controlling the molecular pump group 8 to perform a first vacuuming of the standard volume chamber 1, and then controlling the gas filling module 3 to fill the standard volume chamber 1 with gas for the first time to obtain a first gas filling amount and a first gas filling pressure difference; controlling the molecular pump group 8 to perform a second vacuuming of the standard volume chamber 1, and then controlling the gas filling module 3 to fill the standard volume chamber 1 with gas for the second time to obtain a second gas filling amount and a second gas filling pressure difference; step S3 includes determining the volume of the standard volume chamber 1 based on the first gas filling amount, the second gas filling amount, the first gas filling pressure difference, and the second gas filling pressure difference.

[0040] Specifically, when the target measurement mode is the second measurement mode, the difference between the first inflation volume and the second inflation volume, and the difference between the second inflation pressure and the first inflation pressure are calculated. The volume of the standard volume chamber 1 is determined based on the ratio of the difference in inflation volume and the difference in inflation pressure.

[0041] Specifically, after the molecular pump group 8 performs a second vacuuming of the standard volume chamber 1, the pressure inside the standard volume chamber 1 is the third pressure. After the gas filling module 3 fills the standard volume chamber 1 with gas for the second time, the pressure inside the standard volume chamber 1 is the fourth pressure. The second gas filling pressure difference is obtained based on the third pressure and the fourth pressure.

[0042] For details, please refer to Figure 1 and Figure 4 When the target measurement mode is the second measurement mode, S201: Control the first vacuum valve and the third vacuum valve to close, and the second vacuum valve and the molecular pump group 8 to open. Through the molecular pump group 8, the standard volume chamber 1 and all connecting pipes connected to it are evacuated to a vacuum state; close the second vacuum valve 5 to complete the first evacuation of the standard volume chamber 1 by the molecular pump group 8, and monitor the pressure value in the standard volume chamber 1 at this moment through the vacuum measuring device, that is, the first pressure is P1. S202: Open the first vacuum valve 4, keep the second vacuum valve 5 and the third vacuum valve 6 closed, use the gas filling module 3 to fill the standard volume chamber 1 in the vacuum state with the first standard gas flow rate Q1 within the first gas filling time t1, and complete the first gas filling of the standard volume chamber 1 by the gas filling module 3. Close the first vacuum valve 4 to isolate the gas filling module 3 and the standard volume chamber 1. After the pressure stabilizes, record the pressure value in the standard volume chamber 1 at this moment through the vacuum measuring device, that is, the second pressure P2. S203: Close the first and third vacuum valves and open the second vacuum valve and molecular pump group 8. Pump the standard volume chamber 1 and all connected pipes connected to it to a vacuum state using the molecular pump group 8. Close the second vacuum valve 5 to complete the second vacuuming of the standard volume chamber 1 by the molecular pump group 8. Monitor the pressure value inside the standard volume chamber 1 at this moment using a vacuum measuring device; the third pressure is P3. S204: Open the first vacuum valve 4, keep the second vacuum valve 5 and the third vacuum valve 6 closed, and use the gas filling module 3 to fill the standard volume chamber 1, which is in a vacuum state, with a second standard gas flow rate Q2 within the second filling time t2. This completes the second filling of the standard volume chamber 1 by the gas filling module 3. Close the first vacuum valve 4 to isolate the gas filling module 3 from the standard volume chamber 1. After the pressure stabilizes, record the pressure value inside the standard volume chamber 1 at this moment using a vacuum measuring device; this is the fourth pressure P4. S205: The first inflation volume is determined by the first inflation time t1 and the first standard gas flow rate Q1, the first inflation pressure difference is determined by the first pressure P1 and the second pressure P2, the second inflation volume is determined by the second inflation time t2 and the second standard gas flow rate Q2, the second inflation pressure difference is determined by the third pressure P3 and the fourth pressure P4, and the volume V1 of the standard volume chamber 1 is determined based on the first inflation volume, the first inflation pressure difference, the second inflation volume, and the second inflation pressure difference.

[0043] Specifically, when the target measurement mode is the second measurement mode, the volume V1 of the standard volume chamber 1 is determined by the following formula:

[0044] When the precise measurement mode is selected, the formula uses a subtraction method to cancel out factors that affect measurement uncertainty.

[0045] In one embodiment, the ratio of the second pressure to the first pressure is greater than a first preset threshold. The first preset threshold is 10, meaning the second pressure should be more than 10 times the first pressure.

[0046] In one embodiment, the ratio of the fourth pressure to the third pressure is greater than a second preset threshold. The second preset threshold is 10, meaning the fourth pressure should be more than 10 times the third pressure.

[0047] In one embodiment, the standard gas provided by the inflation module 3 is pure nitrogen.

[0048] In one embodiment, the vacuum measuring device may be a capacitive thin-film vacuum gauge with a measurement uncertainty of 0.4%.

[0049] In one embodiment, the software accompanying the inflation module 3 records time t in milliseconds, providing a gas flow uncertainty of no more than 1.0% and a time measurement uncertainty of no more than 0.2%.

[0050] In one embodiment, the measurement method is calculated to have a combined uncertainty of 1.1%.

[0051] The derivation process of formulas (1) and (2) is introduced as follows: According to Boyle's law in the fundamental laws of gases, for a given mass of gas, when the temperature remains constant, its pressure (p, unit Pa) and volume (V, unit m³) are constant. 3 The product of ) is equal to a constant, that is: This constant is called the amount of gas.

[0052] The amount of gas flowing through a given cross-section per unit time is called flow rate Q, and its unit is Pa·m. 3 / s, the flow rate is proportional to the mass of the gas flowing through (M), according to the Clapham equation, we have: Where R is the universal gas constant, independent of the type of gas; T is the gas temperature. Therefore, when the type of gas is constant (i.e., ...), μ At a constant temperature (as shown in the above formula), within a fixed container, the gas flow rate formula can be uniformly expressed in one form: That is, the change in gas pressure in a fixed container. Multiplying by the container volume V equals the gas flow rate Q flowing into (or out of) the container. arrive Time of pressure change In this application, the pressure change time t measured during different inflation processes is represented by t1 and t2.

[0053] Transforming the above formula, we can obtain formula (1) for measuring volume. When the same measurement is repeated twice, since the measured V1 remains unchanged, but the range of pressure change is slightly different, there will be...

[0054] Transforming formulas (1) and (3), we get:

[0055] Subtract (1) from formula (3ˊ) and then transform and rearrange the terms to obtain formula (2).

[0056] This application uses a vacuum measuring device to measure pressure values ​​P1, P2, P3, and P4. By observing the pressure rise caused by gas flow entering the volume chamber and the cumulative effect of two flow rate measurements, the volume of the standard volume chamber 1 is calculated. This application enables the measurement and calibration of pre-assembled standard flow instruments, improving the accuracy of standard volumes that are susceptible to external factors such as temperature.

[0057] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "a plurality" refers to two or more unless otherwise expressly defined.

[0058] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calibrating a small volume of flow accumulation in a flowmeter, characterized in that, This is used for online volume measurement of the standard volume chamber of a flow meter. The flow meter includes a standard volume chamber, a vacuum flow guide orifice, an inflation module, and a molecular pump assembly. The vacuum flow guide orifice, the inflation module, and the molecular pump assembly are respectively connected to the standard volume chamber. The method includes: In response to a test command, a target measurement mode is determined, the target measurement mode including a first measurement mode and a second measurement mode; According to the target measurement mode, after controlling the molecular pump group to evacuate the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas to obtain the gas filling volume and gas filling pressure difference; The volume of the standard volume chamber is determined based on the inflation volume and the inflation pressure difference.

2. The method for calibrating a small volume of flow accumulation in a flowmeter according to claim 1, characterized in that, When the target measurement mode is the first measurement mode, after the molecular pump group is controlled to perform the first vacuuming of the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas for the first time to obtain the first gas filling amount and the first gas filling pressure difference; the volume of the standard volume chamber is determined according to the first gas filling amount and the first gas filling pressure difference.

3. The method for calibrating a small volume of flow accumulation in a flowmeter according to claim 1, characterized in that, When the target measurement mode is the second measurement mode, after the molecular pump group performs a first vacuuming of the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas for the first time, obtaining a first gas filling amount and a first gas filling pressure difference; after the molecular pump group performs a second vacuuming of the standard volume chamber, the gas filling module is controlled to fill the standard volume chamber with gas for the second time, obtaining a second gas filling amount and a second gas filling pressure difference; the volume of the standard volume chamber is determined based on the first gas filling amount, the second gas filling amount, the first gas filling pressure difference, and the second gas filling pressure difference.

4. A method for calibrating a small volume of flow accumulation in a flowmeter according to any one of claims 2 or 3, characterized in that, After the molecular pump group performs the first vacuuming of the standard volume chamber, the pressure inside the standard volume chamber is the first pressure. After the inflation module performs the first inflation of the standard volume chamber, the pressure inside the standard volume chamber is the second pressure. The first inflation pressure difference is obtained based on the first pressure and the second pressure.

5. The method for calibrating a small volume of flow accumulation in a flow meter according to claim 4, characterized in that, The ratio of the second pressure to the first pressure is greater than the first preset threshold.

6. The method for calibrating a small volume of flow accumulation in a flowmeter according to claim 3, characterized in that, After the molecular pump group performs a second vacuuming of the standard volume chamber, the pressure inside the standard volume chamber is the third pressure. After the inflation module performs a second inflation of the standard volume chamber, the pressure inside the standard volume chamber is the fourth pressure. The second inflation pressure difference is obtained based on the third pressure and the fourth pressure.

7. The method for calibrating a small volume of flow accumulation in a flowmeter according to claim 6, characterized in that, The ratio of the fourth pressure to the third pressure is greater than the second preset threshold.

8. The method for calibrating a small volume of flow accumulation in a flow meter according to claim 2, characterized in that, When the target measurement mode is the first measurement mode, the volume of the standard volume chamber is determined according to the ratio of the first inflation volume to the first inflation pressure difference.

9. The method for calibrating a small volume of flow accumulation in a flow meter according to claim 2, characterized in that, When the target measurement mode is the second measurement mode, the difference between the first inflation volume and the second inflation volume, and the difference between the second inflation pressure and the first inflation pressure are calculated. The volume of the standard volume chamber is determined based on the ratio of the difference in inflation volume and the difference in inflation pressure.

10. The method for calibrating a small volume of flow accumulation in a flowmeter according to claim 1, characterized in that, The standard volume chamber is equipped with a vacuum detection device for measuring the pressure inside the standard volume chamber.

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