High precision flow calibrator with wide range

Abstract

The utility model relates to flow calibration field, concretely relates to a high accuracy flow calibration appearance with wide range of quantity, high accuracy flow calibration appearance with wide range of quantity, including chamber, at least two different range pressure measurement components, incoming flow component, outflow pipe and controller, at least two different range pressure measurement components are used for testing fluid pressure in the chamber respectively, incoming flow component includes incoming flow pipe and sound velocity nozzle, the incoming flow pipe is connected with the chamber through the sound velocity nozzle, the outflow pipe is connected with the chamber, the controller is connected all pressure measurement components, is used for obtaining fluid flow according to the pressure of corresponding pressure measurement component feedback, the utility model discloses can be realized in the high accuracy measurement calibration of wide range.

Description

Technical Field

[0001] This utility model relates to the field of flow calibration, specifically to a high-precision flow calibrator with a wide range. Background Technology

[0002] A flow calibrator (MFV) is a high-precision instrument used to detect, verify, and calibrate the accuracy of MFCs or mass flow meters (MFMs). It is widely used in semiconductor, biopharmaceutical, chemical, and environmental monitoring fields to ensure the accuracy and reliability of flow measurement equipment. The core function of an MFV is to provide a standard flow reference. By comparing it with the flow measurement device (such as an MFC / MFM), it determines whether the measurement error is within the allowable range and makes necessary adjustments or calibrations.

[0003] Flow calibrators typically use the rate of rise method, which involves introducing gas into a container of known volume v and measuring the rate of pressure rise. and temperature And use Relationship ( (where the gas constant is used to determine the flow rate) Traffic passing through With pressure change rate Proportional to temperature Inversely proportional.

[0004] However, existing flow calibrators have the following problems: Firstly, the rapid increase in pressure inside the container will cause the MFC outlet pressure to change continuously. This changing back pressure will cause the MFC to deviate from its set value, introducing errors.

[0005] Secondly, if the pressure change If the resolution of the pressure sensing element is close to or even smaller than that of the actual pressure change, the element may fail to detect the true pressure change, resulting in unreliable flow rates with extremely poor accuracy and repeatability. To improve calibration accuracy, high-precision pressure sensing elements are currently used. However, high precision comes with a smaller measurement range. When calibrating large flow rates, the rapid gas inflow and pressure rise cause significant pressure changes within the measurement time. The error can be very large. When the pressure exceeds the range, the pressure measurement component may be damaged or the reading may saturate. Even if the pressure is still within the range, but close to the upper limit of the range, the absolute error of the pressure measurement component at the high end of its range will increase, resulting in a decrease in the accuracy of the calculated large flow rate. This means that the existing solution is only suitable for small flow rate calibration.

[0006] Therefore, it is urgent to solve the above-mentioned technical problems. Summary of the Invention

[0007] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a high-precision flow calibrator with a wide range of measurement, which can realize high-precision measurement and calibration over a wide range.

[0008] To solve the above-mentioned technical problems, the technical solution of this utility model is: a high-precision flow calibrator with a wide range, comprising: chamber; At least two pressure measurement components with different ranges are used to test the fluid pressure in the chamber. The inlet assembly includes an inlet pipe and a sonic nozzle, wherein the inlet pipe is connected to the chamber through the sonic nozzle; The outlet pipe connects to the chamber; The controller connects to all pressure measurement components and is used to obtain fluid flow rate based on the pressure feedback from the respective pressure measurement components.

[0009] Furthermore, the high-precision flow calibrator with a wide measurement range also includes a temperature measurement component for measuring the fluid temperature within the chamber.

[0010] Furthermore, multiple temperature measurement components are configured and evenly distributed throughout the chamber.

[0011] Furthermore, the controller is also connected to all temperature measurement components to obtain the fluid flow rate based on the pressure fed back by the corresponding pressure measurement components and the average temperature measured by all temperature measurement components.

[0012] Furthermore, the high-precision flow calibrator with a wide measurement range also includes an inlet valve and an outlet valve, wherein the inlet valve is installed on the inlet pipe and the outlet valve is installed on the outlet pipe.

[0013] Furthermore, the controller is connected to the inlet valve and the outlet valve respectively, and is used to control their opening and closing.

[0014] Furthermore, at least two flow inlet components are arranged in parallel, and the throat area of ​​the sonic nozzle of each flow inlet component is different, corresponding to different flow ranges.

[0015] Furthermore, the high-precision flow calibrator with a wide measurement range also includes a vacuum pumping assembly connected to the outlet pipe.

[0016] Furthermore, the pressure measuring component is a vacuum gauge. Attached Figure Description

[0017] Figure 1 This is a block diagram illustrating the principle of the high-precision flow calibrator with a wide measurement range of this utility model. In the diagram, 1 is the chamber; 2 is the pressure measurement assembly; 3 is the inlet pipe; 4 is the sonic nozzle; 5 is the outlet pipe; 6 is the controller; 7 is the temperature measurement assembly; 8 is the inlet valve; 9 is the outlet valve; and 10 is the vacuum assembly. Detailed Implementation

[0018] To make the contents of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0019] like Figure 1 As shown, a high-precision flow calibrator with a wide measuring range includes: Chamber 1; At least two pressure measuring components 2 with different ranges are used to test the fluid pressure in chamber 1; The inlet assembly includes an inlet pipe 3 and a sonic nozzle 4, with the inlet pipe 3 connected to the chamber 1 via the sonic nozzle 4; Outflow pipe 5 connects to chamber 1; The controller 6 is connected to all pressure measurement components 2 and is used to obtain the fluid flow rate based on the pressure fed back by the corresponding pressure measurement components 2.

[0020] Specifically, in this embodiment, a sonic nozzle 4 is installed at the inlet of chamber 1, and pressure measurement components 2 with different ranges are configured. On one hand, a significant pressure drop and sonic flow rate conditions are generated at the sonic nozzle 4. Under sonic conditions, the upstream pressure of the sonic nozzle 4 will not change due to changes in downstream pressure. As long as the pressures downstream and upstream of the sonic nozzle 4 do not exceed the critical pressure ratio, the increase in downstream pressure will not affect the upstream pressure, and therefore will not affect MFC performance. On the other hand, a suitable pressure measurement component 2 is selected based on the flow rate and the final pressure range. When calibrating a small flow rate, a small-range, high-resolution pressure measurement component 2 is selected to ensure the expected pressure change. The resolution is much larger than that of pressure measurement component 2, thus ensuring high accuracy of the final flow rate. When calibrating large flow rates, a large-range pressure measurement component 2 is selected to ensure that the pressure does not exceed the upper limit of its range, allowing the pressure to operate in the middle of its range, avoiding operation near the upper limit where the absolute error is greatest. It should be noted that the resolution of the large-range pressure measurement component 2 is usually lower, but this is acceptable as long as the expected... The pressure is large enough that its relative error can still be controlled within an acceptable range. Therefore, in this embodiment, a sonic nozzle 4 is set at the inlet of chamber 1, and pressure measurement components 2 with different ranges are configured. This can prevent pressure changes in chamber 1 from affecting the operation of MFC, and can also take into account both small and large flow rates, thereby achieving high-precision flow calibration over a wide range.

[0021] In this embodiment, as Figure 1As shown, the high-precision flow calibrator with a wide measurement range may also include a temperature measurement component 7, which is used to measure the fluid temperature in the chamber 1. Multiple temperature measurement components 7 may be configured and evenly distributed in the chamber 1. The temperature measurement components 7 are also connected to the controller 6. The controller 6 obtains the fluid flow rate based on the pressure fed back by the corresponding pressure measurement component 2 and the average temperature measured by all temperature measurement components 7.

[0022] Specifically, controller 6 according to the formula Obtain fluid flow rate ( The gas constant is... (where T is the pressure rise rate, V is the temperature, and v is the chamber volume) to measure flow rate. Considering that the temperature in chamber 1 changes during measurement, it needs to be monitored in real time using temperature measurement components 7. Multiple temperature measurement components 7 are used to obtain the average temperature of the gas. Real-time measurement of the average temperature of the fluid within the chamber and feedback to controller 1 can effectively solve the problem of temperature changes within chamber 1 affecting calibration accuracy.

[0023] In this embodiment, as Figure 1 As shown, a high-precision flow calibrator with a wide flow range may also include an inlet valve 8 and an outlet valve 9. The inlet valve 8 is installed on the inlet pipe 3, and the outlet valve 9 is installed on the outlet pipe 5. A controller 6 is connected to the inlet valve 8 and the outlet valve 9 respectively to control their opening and closing. Both the inlet valve 8 and the outlet valve 9 can be diaphragm valves.

[0024] In this embodiment, preferably, as follows: Figure 1 As shown, at least two inlet components are arranged side by side. The throat area of ​​the sonic nozzle 4 of each inlet component is different. Each sonic nozzle 4 corresponds to a flow range (depending on the different throat areas; when the flow range is large, a sonic nozzle 4 with a larger throat area is used, which provides a lower inlet pressure to meet the maximum inlet pressure requirement of MFV; when the flow range is small, a sonic nozzle 4 with a smaller throat area is used, which provides a longer calibration time and can increase measurement accuracy). As the range increases, the number of sonic nozzles 4 also increases.

[0025] In this embodiment, preferably, as follows: Figure 1 As shown, the high-precision flow calibrator with a wide measuring range may also include a vacuum pump assembly 10, which is connected to the outlet pipe 5. The vacuum pump assembly 10 may be, but is not limited to, a vacuum pump.

[0026] In this embodiment, the pressure measurement component 2 can be a vacuum gauge. Vacuum gauges have extremely high resolution and sensitivity, making them ideal for use as pressure sensors in MFVs.

[0027] Figure 1 The working process of the high-precision flow calibrator with a wide measuring range shown is as follows: The MFC to be calibrated is connected to the inlet pipe 3, which is located upstream of the inlet valve 8. First, close all upstream inlet valves 8, open the downstream outlet valve 9, and open the vacuum assembly 10 to purge chamber 1. After purging, open the MFC to be calibrated. When the controller 6 receives the user's detection command, the program determines which flow range the flow belongs to and selects to open the appropriate inlet valve 8, allowing the gas to enter chamber 1 through the corresponding sonic nozzle 4. After the airflow stabilizes, close the downstream outlet valve 9. Over a period of time, the pressure measurement assembly 2 measures the gas pressure change in chamber 1, and the temperature measurement assembly 7 measures the gas temperature change. The actual flow rate is calculated based on the pressure rise rate and temperature. After obtaining the actual flow rate, open the downstream outlet valve 9 to discharge the gas. The user can calibrate the MFC based on the measured flow rate.

[0028] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high-precision flow calibrator with a wide measuring range, characterized in that, include: Chamber (1); At least two pressure measurement components (2) with different ranges are used to test the fluid pressure in the chamber (1); The inlet assembly includes an inlet pipe (3) and a sonic nozzle (4), wherein the inlet pipe (3) is connected to the chamber (1) through the sonic nozzle (4); Outflow pipe (5) is connected to the chamber (1); The controller (6) is connected to all pressure measurement components (2) to obtain the fluid flow rate based on the pressure fed back by the corresponding pressure measurement components (2).

2. The high-precision flow calibrator with a wide measuring range according to claim 1, characterized in that, It also includes a temperature measurement component (7) for measuring the fluid temperature inside the chamber (1).

3. The high-precision flow calibrator with a wide measuring range according to claim 2, characterized in that, Multiple temperature measurement components (7) are configured and evenly distributed in the chamber (1).

4. The high-precision flow calibrator with a wide measuring range according to claim 3, characterized in that, The controller (6) is also connected to all temperature measurement components (7) to obtain the fluid flow rate based on the pressure fed back by the corresponding pressure measurement component (2) and the average temperature measured by all temperature measurement components (7).

5. The high-precision flow calibrator with a wide measuring range according to claim 1, characterized in that, It also includes an inlet valve (8) and an outlet valve (9), the inlet valve (8) being installed on the inlet pipe (3) and the outlet valve (9) being installed on the outlet pipe (5).

6. The high-precision flow calibrator with a wide measuring range according to claim 5, characterized in that, The controller (6) is connected to the inlet valve (8) and the outlet valve (9) respectively, and is used to control the opening and closing.

7. The high-precision flow calibrator with a wide measuring range according to claim 1, characterized in that, The inlet components are arranged in parallel at least two, and the throat area of ​​the sonic nozzle (4) of each inlet component is different, corresponding to different flow ranges.

8. The high-precision flow calibrator with a wide measuring range according to claim 1, characterized in that, It also includes a vacuum pumping assembly (10), which is connected to the outlet pipe (5).

9. The high-precision flow calibrator with a wide measuring range according to claim 1, characterized in that, The pressure measuring component (2) is a vacuum gauge.

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