Method and apparatus for calibrating orifice flow coefficients using pressure-mass

Abstract

The application discloses a method and device for calibrating orifice plate flow coefficient by pressure-mass method, wherein the method realizes orifice plate calibration by weighing the feed container before and after use and optimizing test means; the device comprises a feed container, a transition container, a material collecting container and a vacuum pump group connected in sequence through vacuum pipelines; a first pressure gauge is arranged on the vacuum pipeline between the feed container and the transition container; a control valve and a second pressure gauge are arranged on the vacuum pipeline between the transition container and the material collecting container; and the orifice plate to be calibrated is arranged in the vacuum pipeline between the transition container and the material collecting container. The application realizes orifice plate calibration by optimizing test means and reducing test requirements; the gas collected at each test point does not need to be weighed separately, the test operation steps and workload are reduced, the test points can be increased freely to improve the accuracy of flow coefficient calibration; and data calculation is introduced in the orifice plate calibration process, thereby reducing the requirement on system hardware.

Description

Technical Field

[0001] This invention belongs to the field of flow coefficient testing and calibration of gas flow control devices in the vacuum field, specifically relating to a method and apparatus for calibrating the flow coefficient of an orifice plate using the pressure-mass method. Background Technology

[0002] In vacuum systems, a certain amount of gas is typically required to be stably introduced into the vacuum pipeline. Gas flow rate control is achieved by installing an orifice plate with a specific orifice diameter, and the gas flow rate through the orifice plate over a certain period is calculated using the orifice plate flow rate formula. The orifice plate flow rate formula is a linear function expression related to the pressure in front of the orifice plate. The basic principle for determining this expression is to experimentally measure the flow rate corresponding to multiple pressure points on the orifice plate, and then perform linear fitting to obtain the slope and intercept of the linear function expression. Commonly used methods for determining the orifice plate flow rate formula include the weighing method, the pressure-volume method, and the method of calibrating an unknown orifice plate using a known orifice plate. The weighing method directly determines the flow rate corresponding to the orifice plate pressure by collecting the gas weight and collection time; the pressure-volume method indirectly calculates the flow rate corresponding to the orifice plate pressure by using the pressure drop, drop time, and volume of the transition container, based on the ideal gas law. Regardless of the method used, the goal is to determine the flow rate corresponding to the orifice plate pressure and fit a functional relationship between the orifice plate flow rate and pressure.

[0003] The conventional orifice plate flow coefficient calibration process requires at least one of the following prerequisites: multiple receiving containers (weighing method), intermediate container volume calibration (pressure-volume method), orifice plates with known flow coefficients (series calibration method), etc.

[0004] Furthermore, existing calibration methods for orifice plate flow coefficients have a long overall calibration cycle and may also have problems such as long material collection time reducing weighing deviation (weighing method), needing to perform volume calibration through standard containers (pressure-volume method), or needing to perform orifice plate calibration through other methods first for known orifice plates (series calibration method). Summary of the Invention

[0005] This invention is proposed to overcome the shortcomings of the prior art, and its purpose is to provide a method and apparatus for calibrating the flow coefficient of an orifice plate using the pressure-mass method.

[0006] This invention is achieved through the following technical solution:

[0007] A method for calibrating the flow coefficient of an orifice plate using a pressure-mass method includes the following steps:

[0008] (I) Measure the mass m0 of the feeding container before use, connect it to the calibration system, and then evacuate the system section after the feeding container. After evacuation is completed, start the test.

[0009] (II) Use the control valve to disconnect the pipeline after the transition container, use the feed container to pressurize the transition container, and record the pressurization amount.

[0010] (III) Control the pressure P in front of the orifice plate to be calibrated by controlling the valve. K1 The value is a1, which records the pressure drop in the transition container after a period of time Δt1 under steady-state conditions.

[0011] (IV) Repeat step (III) by controlling the pressure P in front of the orifice plate to be calibrated via the control valve. K1 For different values ​​of a i And record the corresponding time interval Δt under steady state. i Pressure drop in the inner transition container

[0012] (V) When the pressure inside the transition container is insufficient, pressurize the transition container and record the pressure P in front of the orifice to be calibrated under stable conditions before and after pressurization. K1 The value is b i And record a portion of the time Δt corresponding to the steady state. ci Pressure increase in the inner transition container

[0013] (VI) After the test, disassemble the feeding container and weigh it to obtain the mass m1 of the feeding container after use;

[0014] (VII) According to P K1 The regulated voltage value a i and time Δt i and the corresponding pressure drop Fit the pressure drop rate of the transition container and the regulated voltage a i linear relationship Where A and B are constants obtained from the fitting;

[0015] (VIII) Calculate the value recorded in step (V) based on the linear relationship in step (VII). Pressure drop in the transition container

[0016] (IX) Total pressure change during filling The change in mass of the feeding container before and after use, Δm = m0 - m1, yields ΔP. f =CΔm, where C is a calculated constant;

[0017] (X) Substituting the relationship calculated in step (IX) into the relationship fitted in step (VII), the flow coefficient of the orifice plate to be calibrated, q = Δm / Δt = (aA-B) / C, can be obtained.

[0018] In the above technical solution, the system and test environment temperature T0 are kept constant during the test.

[0019] An apparatus for calibrating the flow coefficient of an orifice plate using the pressure-mass method includes a feed container, a transition container, a receiving container, and a vacuum pump unit connected in sequence via vacuum pipelines. A pressure gauge I is installed in the vacuum pipeline between the feed container and the transition container, and a control valve and a pressure gauge II are installed in the vacuum pipeline between the transition container and the receiving container. The orifice plate to be calibrated is placed in the vacuum pipeline between the transition container and the receiving container.

[0020] In the above technical solution, the control valve is located at one end near the transition container; the orifice plate to be calibrated is located at one end near the receiving container.

[0021] In the above technical solution, the No. II pressure gauge is located between the control valve and the orifice plate to be calibrated, and is positioned close to the orifice plate to be calibrated.

[0022] In the above technical solution, a valve is provided at the outlet of the feeding container.

[0023] The above technical solution also includes a high-pressure gas cylinder for pressurizing the feeding container.

[0024] The beneficial effects of this invention are:

[0025] This invention provides a method and apparatus for calibrating the flow coefficient of a flow orifice plate in a vacuum system using the pressure-mass method. By optimizing experimental methods and reducing experimental requirements, the flow coefficient of the orifice plate can be calibrated with minimal hardware requirements. It eliminates the need to weigh the gas collected at each test point separately, reducing experimental operation steps and workload, and allows for the addition of test points to improve the accuracy of flow coefficient calibration. The orifice plate calibration process incorporates data calculation, further reducing the requirements for system hardware. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device for calibrating the orifice plate flow coefficient using the pressure-mass method of the present invention.

[0027] in:

[0028] 1. Feeding container

[0029] 2. Transition Container

[0030] 3. Receiving container

[0031] 4 Vacuum pump set

[0032] 5. Control valves

[0033] 6. I pressure gauge

[0034] 7. Pressure gauge No. Ⅱ

[0035] 8 Valves

[0036] 9. High-pressure gas cylinders

[0037] 10. Well plate to be calibrated.

[0038] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the method and apparatus for calibrating the orifice plate flow coefficient by pressure-mass method of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1 As shown, an apparatus for calibrating the flow coefficient of an orifice plate using the pressure-mass method includes a feed container 1, a transition container 2, a receiving container 3, and a vacuum pump group 4 connected in sequence via vacuum pipelines. A pressure gauge 6 (No. I) is installed in the vacuum pipeline between the feed container 1 and the transition container 2, and a control valve 5 and a pressure gauge 7 (No. II) are installed in the vacuum pipeline between the transition container 2 and the receiving container 3. The orifice plate 10 to be calibrated is placed in the vacuum pipeline between the transition container 2 and the receiving container 3.

[0041] The control valve 5 is located at one end near the transition container 2.

[0042] The orifice plate 10 to be calibrated is located at one end near the receiving container 3.

[0043] The pressure gauge 7 of type II is located between the control valve 5 and the orifice plate 10 to be calibrated, and is positioned close to the orifice plate 10 to be calibrated.

[0044] A valve 8 is installed at the outlet of the feeding container 1.

[0045] It also includes a high-pressure gas cylinder 9 for pressurizing the feed container 1.

[0046] Example 2

[0047] Based on the apparatus of Example 1, a method for calibrating the flow coefficient of an orifice plate using the pressure-mass method includes the following steps:

[0048] (i) Measure the mass m0 of the feeding container before use, connect it to the calibration system, close the valve at the outlet of the feeding container, evacuate the rest of the system, start the test after evacuation is completed, and maintain the system and test environment temperature T0 constant during the test.

[0049] (ii) Use the control valve to disconnect the pipeline after the transition container, use the feed container to pressurize the transition container, and record the pressurization amount.

[0050] (iii) Control the pressure P in front of the orifice plate to be calibrated by controlling the valve. K1 The value is a1, which records the pressure drop in the transition container after a period of time Δt1 under steady-state conditions.

[0051] (iv) Repeat step (iii) by controlling the pressure P in front of the orifice plate to be calibrated via the control valve. K1 For different values ​​of a i And record the corresponding time interval Δt under steady state. i Pressure drop in the inner transition container

[0052] (v) Because the gas pressure inside the transition container needs to be controlled within a certain range during the experiment, different stabilizing pressure values ​​P K1 The adjustment process requires pressurization, and the pressure P in front of the orifice plate must be stabilized before and after pressurization. K1 The value is b i Record the time Δt corresponding to a portion of the steady state. ci Pressure increase in the transition container

[0053] (vi) After the test, the feeding container was disassembled and weighed to obtain the mass m1 after use;

[0054] (vii) Based on different regulated voltage values ​​a i and the corresponding time Δt i and pressure drop Fit the pressure drop rate of the transition container and the regulated voltage a i linear relationship Where A and B are constants obtained from the fitting;

[0055] (ⅷ) Calculate the pressure drop in the transition vessel caused by the orifice flow rate recorded in the steady state in step (ⅴ) based on the linear relationship in step (ⅶ).

[0056] (ⅸ) Total pressure change during filling The change in mass of the feeding container before and after use, Δm = m0 - m1, yields ΔP. f =CΔm, where C is a calculated constant;

[0057] (x) Substituting the relationship calculated in step (x) into the relationship fitted in step (vi) and transforming it, we can obtain the flow coefficient of the orifice plate to be calibrated, q = Δm / Δt = (aA-B) / C.

[0058] Note: Step (v) is based on the pressure value of the transition vessel and can be interspersed between any steps. The actual pressurization process must be included in the recording of Δt. ci , During the value process, record Δt. ci , The value process includes the pressure P before the stabilizing orifice plate. K1 The value is b i During the process.

[0059] Taking the calibration gas CF4 (an organic gas) as an example, the specific implementation method for calibrating the orifice coefficient of a 2.0 mm orifice is as follows:

[0060] (i) The mass of the feeding container before use was measured to be m0 = 18354.2g. After being connected to the system, the container was evacuated. During the test, the system temperature was kept constant at 20℃.

[0061] (ii) Use the control valve to shut off the pipeline, use the feed container to pressurize the transition container, and record the pressurization amount.

[0062] (iii) Control the pressure P in front of the orifice plate by controlling the valve. K1 The value is 8.8 hPa. The time corresponding to a portion of the steady state is 308 s, and the pressure drop in the transition container is 97.5 hPa.

[0063] (iv) Repeatedly control different voltage regulators P K1 The values ​​are [7.0 5.3 3.5 1.8] hPa, and the corresponding time for a portion of the steady state is recorded as [425 608 921 1824] s, and the pressure drop in the transition container is recorded as [107.7 115.5 113.6 109.4] hPa;

[0064] (v) The gas in the transition container was pressurized four times during the experiment. The pressure P before and after pressurization was the pressure P before the stabilizing orifice plate. K1 The values ​​are [8.8 7.0 5.3 3.5] hPa. Record the corresponding time [300 300 300 300] s and the pressure increase of the transition container [105.2 103.7 121.4 113.8] hPa during the steady state.

[0065] (vi) After the test, the feeding container was disassembled and weighed, and the weight after use was 18335.9g;

[0066] (vii) Based on different stabilizing values ​​[8.8 7.0 5.3 3.5 1.8] hPa and corresponding times [308 425 608 921 1824] s and pressure drops [97.5 107.7 115.5 113.6 109.4] hPa, the pressure drop rate of the transition vessel was fitted. and the regulated voltage a i linear relationship

[0067] (ⅷ) Calculate the pressure drop in the transition vessel caused by the flow rate of the orifice plate during the four steady-state records in step (ⅶ) based on the linear relationship in step (ⅴ) [95 76 57 37] hPa;

[0068] (ⅸ) The total pressure change ΔP during filling f =914.5 hPa and the mass change of the feeding container before and after use, Δm = 18.3 g, yield ΔP f =49.793Δm;

[0069] (x) Substituting the relationship calculated in step (x) into the relationship fitted in step (x), we obtain the orifice plate flow coefficient q (g / h) = 2.648P. K1 (hPa)-0.389.

[0070] This invention provides a method and apparatus for calibrating the flow coefficient of a flow orifice plate in a vacuum system using the pressure-mass method. By optimizing experimental methods and reducing experimental requirements, the flow coefficient of the orifice plate can be calibrated with minimal hardware requirements. It eliminates the need to weigh the gas collected at each test point separately, reducing experimental operation steps and workload, and allows for the addition of test points to improve the accuracy of flow coefficient calibration. The orifice plate calibration process incorporates data calculation, further reducing the requirements for system hardware.

[0071] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0072] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0073] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0074] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for calibrating the flow coefficient of an orifice plate using the pressure-mass method, characterized in that: Includes the following steps: (I) Measure the mass m0 of the feeding container before use, connect it to the calibration system, and then evacuate the system section after the feeding container. After evacuation is completed, start the test. (II) Use the control valve to cut off the pipeline after the transition container, use the feed container to pressurize the transition container, and record the pressurization amount ΔP. f1 ; (III) Control the pressure P in front of the orifice plate to be calibrated by controlling the valve. K1 The value is a1, which records the pressure drop ΔP in the transition container after a period of time Δt1 under steady-state conditions. fx1 ; (IV) Repeat step (III) by controlling the pressure P in front of the orifice plate to be calibrated via the control valve. K1 For different values ​​of a i And record the corresponding time interval Δt under steady state. i Pressure drop ΔP in the inner transition container fxi ; (V) When the pressure inside the transition container is insufficient, pressurize the transition container and record the pressure P in front of the orifice to be calibrated under stable conditions before and after pressurization. K1 The value is b i And record a portion of the time Δt corresponding to the steady state. ci Pressure increase ΔP in the inner transition container fci ; (VI) After the test, disassemble the feeding container and weigh it to obtain the mass m1 of the feeding container after use; (VII) According to P K1 The regulated voltage value a i and time Δt i and the corresponding pressure drop ΔP fxi Fit the pressure drop rate ΔP in the transition container fxi / Δt i and the regulated voltage a i The linear relationship ΔP fxi / Δt i =a i AB, where A and B are constants obtained from the fitting; (VIII) Calculate ΔP recorded in step (V) based on the linear relationship in step (VII). fci Pressure drop ΔP in the transition container fcxi =(b i AB) / Δt ci ; (IX) The total pressure change ΔP during filling f =ΔP f1 +∑ΔP fcxi +∑ΔP fxi The change in mass of the feeding container before and after use, Δm = m0 - m1, yields ΔP. f =CΔm, where C is a calculated constant; (X) Substitute the relationship calculated in step (IX) into the relationship fitted in step (VII) and transform it to obtain the flow coefficient q=Δm / Δt=(aA-B) / C of the orifice plate to be calibrated, where a is the stabilizing value of the pressure PK1 in front of the orifice plate to be calibrated; In steps (I) to (X), the system and test environment temperature T0 is kept constant.

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