Static pressure error test system and method for pressure transmitters

Abstract

The application provides a kind of pressure transmitter static pressure error test system and method, system includes measured pressure transmitter, including low pressure end and high pressure end;Piston unit, gas path, isolation stop valve, first pressure regulator assembly, second pressure regulator assembly and weight group.Piston unit includes first piston assembly and second piston assembly;Gas path includes air inlet passage, first branch and second branch, first branch is connected with low pressure end and first piston assembly, and second branch is connected with high pressure end and second piston assembly;Isolation stop valve is arranged on first branch;Weight group includes static pressure weight and differential pressure weight.When testing, by loading static pressure weight on piston unit, the same static pressure is generated at both ends of measured pressure transmitter, after closing isolation stop valve, load differential pressure weight on second piston assembly and cooperate second pressure regulator assembly, generate differential pressure at both ends of measured pressure transmitter, compare the reading of measured pressure transmitter with standard differential pressure value to determine whether measured pressure transmitter is qualified.

Description

Technical Field

[0001] This invention relates to the field of pressure generation technology in pressure gauge measurement, and particularly to a static pressure error testing system and method for pressure transmitters. Background Technology

[0002] With the rapid development of the differential pressure transmitter application industry, the importance of metrological calibration of differential pressure instruments under high static pressure has become increasingly prominent in the metrology field.

[0003] Currently, high static pressure differential pressure measurements are mostly performed using differential pressure sensors. However, the performance of differential pressure sensors varies significantly with changes in the static pressure environment. Therefore, it is necessary to simulate the actual working conditions of differential pressure instruments during testing and calibration, i.e., to test differential pressure transmitters under high static pressure conditions to ensure the reliability of their measured values. However, existing technologies lack calibration methods that can simultaneously meet the requirements of high static pressure and low differential pressure measurements. Existing technologies for low differential pressure measurements of pressure transmitters under high static pressure suffer from insufficient accuracy and poor adaptability. Summary of the Invention

[0004] This invention provides a static pressure error testing system and method for pressure transmitters to solve the problems of insufficient accuracy and poor adaptability of pressure transmitters under high static pressure in the prior art.

[0005] This invention provides a static pressure error testing system for a pressure transmitter, comprising a pressure transmitter under test, wherein the pressure transmitter under test includes a low-pressure end and a high-pressure end, and the testing system includes: The piston unit includes a first piston assembly and a second piston assembly; The gas path includes an air inlet passage, a first branch, and a second branch; the air inlet passage is used to connect to a high-pressure gas source, and the first branch and the second branch are respectively connected to the air inlet passage; the first branch is connected to the low-pressure end of at least one pressure transmitter under test, and the first branch is connected to the first piston assembly; the second branch is connected to the high-pressure end of at least one pressure transmitter under test, and the second branch is connected to the second piston assembly. An isolation shut-off valve is installed on the first branch and is used to cut off or connect the first branch with the air intake passage. A first pressure regulator assembly is disposed on the first branch and located between the isolation shut-off valve and the first piston assembly. The first pressure regulator assembly is used to regulate the gas pressure in the first piston assembly. A second pressure regulator assembly is disposed on the second branch, and the second pressure regulator assembly is used to regulate the gas pressure in the second piston assembly; The weight set includes static pressure weights and differential pressure weights; the static pressure weights are used to load the first piston assembly and the second piston assembly to generate the same static pressure across the pressure transmitter under test; the differential pressure weights are used to load the first piston assembly or the second piston assembly to generate a differential pressure across the pressure transmitter under test.

[0006] In one embodiment of the present invention, the testing system further includes a gas source shut-off valve, which is disposed on the air intake passage and is used to connect or disconnect the air intake passage from the high-pressure gas source.

[0007] In one embodiment of the present invention, both the first piston assembly and the second piston assembly include a main body, a piston component, a buffer sleeve, a pressure cap, a tray, and a hanging basket; The main body is provided with a guide portion, which is used to guide the piston component to move along the axial direction of the main body; The main body is also provided with an air intake pipe, an oil intake pipe, a manifold, and a pressure discharge pipe; The air outlet of the air inlet pipe corresponds to the confluence area, and the air pressure collected in the confluence area is used to push the piston component to move along the guide portion so that the piston component is in a suspended state; The oil outlet of the oil inlet pipe corresponds to the guide section; The pressure relief pipeline is connected to the manifold, and the pressure relief pipeline is used to discharge the gas and oil from the manifold to the main body; The buffer sleeve is fitted on the outside of the piston component, the pressure cap is fitted on the outside of the buffer sleeve, the tray is disposed on the top of the pressure cap, and the hanging basket abuts against the tray; The tray is used to load differential pressure weights, and the hanging basket is used to load static pressure weights.

[0008] In one embodiment of the present invention, the testing system further includes a first pressure relief valve and a second pressure relief valve, wherein the first pressure relief valve is connected to the pressure discharge pipeline of the first piston assembly; and the second pressure relief valve is connected to the pressure discharge pipeline of the second piston assembly.

[0009] In one embodiment of the present invention, the testing system further includes an oil cup, the oil cup including a cup body, a plug and an oil drain valve, the cup body being used to load lubricating oil, the plug being used to seal the cup body, and the oil drain valve being located at the bottom of the cup body and used to drain the lubricating oil from the cup body; The cup body is provided with a pressure balancing inlet and a lubricating oil outlet. The pressure balancing inlet is connected to a high-pressure air source, and the lubricating oil outlet is connected to the oil inlet pipe.

[0010] In one embodiment of the present invention, both the first pressure regulator assembly and the second pressure regulator assembly include a cylinder, a push rod, a lead screw, a handwheel, and a slotted cylinder; The cylinder is provided with an interface, the cylinder interface of the first pressure regulator assembly is used to communicate with the first branch, and the cylinder interface of the second pressure regulator assembly is used to communicate with the second branch. The push rod is located inside the cylinder, and the push rod is in transition fit with the cylinder; The slotted cylinder is connected to the cylinder, the lead screw is threaded to the slotted cylinder, one end of the lead screw axially close to the cylinder is connected to the push rod, and the other end is connected to the handwheel.

[0011] In one embodiment of the present invention, the cylinder is provided with a first mounting groove and a second mounting groove coaxially at one end away from the interface along the axial direction. The second mounting groove is used to install a sealing component, and the sealing component is used to seal the gap between the push rod and the second mounting groove. The first mounting groove is used to install a nut, and the nut is sleeved on the push rod and used to press the sealing component.

[0012] In one embodiment of the present invention, the sealing assembly includes a copper sleeve, which is disposed in the second mounting groove and sleeved on the push rod. The copper sleeve abuts against the bottom surface of the second mounting groove and the nut along the axial direction of the cylinder. A first sealing ring and a second sealing ring are sleeved on the copper sleeve, and the first sealing ring and the second sealing ring abut against the side wall of the second mounting groove. The nut has a sealing groove at one end facing the copper sleeve, and a third sealing ring is provided in the sealing groove. The third sealing ring is sleeved on the push rod.

[0013] This application also provides a method for testing the static pressure error of a pressure transmitter, including the static pressure error testing system for a pressure transmitter as described above, the method comprising: By loading static pressure weights corresponding to a preset static pressure onto the hanging baskets of the first piston assembly and the second piston assembly; Close the first pressure relief valve and the second pressure relief valve, open the air source shut-off valve and the isolation shut-off valve, and the high-pressure air source enters the system through the air inlet passage. It is distributed to the low-pressure end of the first piston assembly and the pressure transmitter through the first branch, and distributed to the high-pressure end of the second piston assembly and the pressure transmitter through the second branch, until the internal air pressure of the first piston assembly and the second piston assembly lifts the piston component to a suspended state. Close the gas source shut-off valve and the isolation shut-off valve, and load a differential pressure weight corresponding to the preset differential pressure onto the tray of the second piston assembly; The air pressure inside the second piston assembly is adjusted by the second pressure regulator assembly, so that the piston component inside the second piston assembly is restored to a suspended state. The differential pressure reading of the pressure transmitter under test is compared with the preset differential pressure. The error between the differential pressure reading and the preset differential pressure is calculated. If the error is within the preset allowable error range, the pressure transmitter under test is deemed qualified. If the error exceeds the preset allowable error range, the pressure transmitter under test is deemed unqualified.

[0014] In one embodiment of the present invention, a differential pressure weight with a preset differential pressure is loaded on the tray of the first piston assembly, and the air pressure inside the first piston assembly is adjusted by the first pressure regulator assembly to restore the piston component inside the first piston assembly to a suspended state, thereby generating a reverse differential pressure between the low-pressure end and the high-pressure end of the pressure transmitter under test, and readings of the pressure transmitter under test are read and compared with the preset differential pressure.

[0015] The beneficial effects of this invention: The static pressure error testing system and method for pressure transmitters proposed in this invention, by setting up a first piston assembly and a second piston assembly, and configuring a gas path such that the first branch connects to the low-pressure end of at least one pressure transmitter under test and the first piston assembly, and the second branch connects to the high-pressure end of at least one pressure transmitter under test and the second piston assembly, by loading static pressure weights of the same mass onto the first piston assembly and the second piston assembly, and by introducing high-pressure gas into the gas path, the piston components within the first piston assembly and the second piston assembly are in a suspended state, thereby generating the same static pressure at the low-pressure end and the high-pressure end of the pressure transmitter under test, overcoming the limitations of existing methods. Existing technologies that allow the low-pressure end to be vented to the atmosphere neglect static pressure error. This application addresses this issue by installing an isolation shut-off valve on the first branch. After establishing the same static pressure, the connection between the first branch and the intake and second branches can be severed, locking the low-pressure end. A differential pressure weight is then loaded onto the second piston assembly, and fine-tuned with the second pressure regulator assembly to generate a precise micro-differential pressure. This differential pressure value is determined by the mass of the differential pressure weight. By comparing the differential pressure generated by the system with the reading of the pressure transmitter under test, the error between the reading and the standard value is calculated. This error is then compared with a preset allowable error range to assess the measurement accuracy of the pressure transmitter and determine its qualification. This application achieves accurate calibration of the micro-differential pressure measurement accuracy of pressure transmitters under high static pressure conditions, providing a high-precision technical means for testing the static pressure error of pressure transmitters. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] In the attached diagram: Figure 1 This is a schematic diagram of a static pressure error testing system for a pressure transmitter provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a first piston assembly or a second piston assembly provided in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a damping valve provided in one embodiment of the present invention; Figure 4 This is a schematic diagram of the displacement detection device provided in one embodiment of the present invention; Figure 5 This is a flowchart of a static pressure error testing method for a pressure transmitter provided in one embodiment of the present invention.

[0018] The attached figures are labeled as follows: First piston assembly 1, second piston assembly 2, air intake passage 301, first branch 302, second branch 303, pressure transmitter 4, low-pressure end 401, high-pressure end 402, isolation shut-off valve 5, first pressure regulator assembly 6, second pressure regulator assembly 7, first loading zone 8, second loading zone 9, air source shut-off valve 10, main body 11, guide section 1101, air intake pipe 1102, oil intake pipe 1103, manifold 1104, pressure discharge pipe 1105, piston component 12, buffer 13. Punch sleeve, 14. Pressure cap, 15. Tray, 16. Hanging basket, 17. First pressure relief valve, 18. Second pressure relief valve, 19. Oil cup, 20. Damping valve, 20. Knurled nut, 2001. Connecting rod, 2002. Valve body, 2003. Carbide ring, 2004. Copper washer, 2005. Stepped copper washer, 2006. Valve needle, 2007. Hexagonal clamping nut, 2008. Handle, 2009. High-pressure end bracket, 21. Low-pressure end bracket, 22. High-pressure end ranging sensor, 23. Low-pressure end ranging sensor, 24. Display, 25. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0022] Please combine Figures 1 to 4 As shown, the present invention provides a static pressure error testing system for pressure transmitters.

[0023] In an exemplary embodiment of this application, a static pressure error testing system for a pressure transmitter includes a pressure transmitter 4 under test, which includes a low-pressure end 401 and a high-pressure end 402. The testing system includes: The piston unit includes a first piston assembly 1 and a second piston assembly 2; the first piston assembly 1 and the second piston assembly 2 have the same structure.

[0024] The gas path includes an air inlet passage 301, a first branch passage 302, and a second branch passage 303. The air inlet passage 301 is used to connect to a high-pressure gas source. The first branch passage 302 and the second branch passage 303 are respectively connected to the air inlet passage 301. The first branch passage 302 is connected to the low-pressure end 401 of at least one pressure transmitter 4 under test and is connected to the first piston assembly 1. The second branch passage 303 is connected to the high-pressure end 402 of at least one pressure transmitter 4 under test and is connected to the second piston assembly 2. The first branch 302 can be connected to multiple first branches, which are respectively connected to the low-pressure end 401 and the first piston assembly 1 of multiple pressure transmitters 4 under test. The multiple first branches connect the multiple low-pressure ends 401 and the first piston assembly 1 in parallel. Similarly, the second branch 303 can be connected to multiple second branches, which are respectively connected to the high-pressure end 402 and the second piston assembly 2 of multiple pressure transmitters 4 under test. The multiple second branches connect the multiple high-pressure ends 402 and the second piston assembly 2 in parallel. This allows the test system shown in this embodiment to perform error tests on multiple pressure transmitters 4 simultaneously, effectively improving test efficiency.

[0025] An isolation shut-off valve 5 is installed on the first branch 302 to cut off or connect the first branch 302 with the air intake passage 301. Since the first branch 302 and the second branch 303 are connected in parallel, and the isolation shut-off valve 5 is installed on the first branch 302, when the isolation shut-off valve 5 cuts off the connection between the first branch 302 and the air intake passage 301, it also cuts off the connection between the first branch 302 and the second branch 303. By simultaneously cutting off the air intake passage 301 and closing the isolation shut-off valve 5, the pressure of the first branch 302 and the second branch 303 is locked. At this time, a differential pressure can be formed across the two ends of the pressure transmitter 4 by loading a differential pressure weight onto the first piston assembly 1 or the second piston assembly 2.

[0026] The first pressure regulator assembly 6 is disposed on the first branch 302 and located between the isolation shut-off valve 5 and the first piston assembly 1. The first pressure regulator assembly 6 is used to regulate the gas pressure in the first piston assembly 1. The second pressure regulator assembly 7 is disposed on the second branch 303. The second pressure regulator assembly 7 is used to regulate the gas pressure in the second piston assembly 2. By fine-tuning the first piston assembly 1 and the second piston assembly 2 through the first pressure regulator assembly 6 and the second pressure regulator assembly 7, the first piston assembly 1 and the second piston assembly 2 are both in a suspended state, thereby ensuring that the static pressure at both ends of the pressure transmitter 4 is consistent.

[0027] The weight set includes static pressure weights and differential pressure weights; the static pressure weights are used to load the first piston assembly 1 and the second piston assembly 2 to generate the same static pressure across the pressure transmitter 4 under test; the differential pressure weights are used to load the first piston assembly 1 or the second piston assembly 2 to generate a differential pressure across the pressure transmitter 4 under test.

[0028] By simultaneously loading static pressure weights of the same mass onto the first piston assembly 1 and the second piston assembly 2, the same static pressure is formed across the pressure transmitter 4 under test. By changing the mass of the static pressure weights, the error test of the pressure transmitter 4 under different static pressure conditions can be simulated. By closing the air inlet passage 301 and the isolation shut-off valve 5, a differential pressure weight can be loaded onto the first piston assembly 1 or the second piston assembly 2 to form a differential pressure across the pressure transmitter 4 under test. Similarly, by changing the differential pressure weights of different masses, different differential pressure conditions can be simulated across the pressure transmitter 4. By reading the differential pressure value of the pressure transmitter 4 and comparing it with the differential pressure standard value formed by the system, the measurement accuracy of the pressure transmitter 4 can be tested to see if it is up to standard.

[0029] For example, the specifications of the static pressure weights include 5kg, 4kg, 2kg, and 1kg, corresponding to static pressure values ​​of 5MPa, 4MPa, 2MPa, and 1MPa, respectively; the specifications of the differential pressure weights include 500g, 200g, 100g, 50g, 20g, 10g, 5g, 2g, 1g, 500mg, and 200mg, corresponding to differential pressure values ​​of 500kPa, 200kPa, 100kPa, 50kPa, 20kPa, 10kPa, 5kPa, 2kPa, 1kPa, 500Pa, and 200Pa, respectively. By combining and loading the above static pressure weights, the maximum static pressure that this application can load is 80MPa, and the static pressure resolution is 1MPa; by combining and loading the above differential pressure weights, the minimum differential pressure that this application can achieve is 0.2kPa, the differential pressure measurement range is 0–150kPa, the differential pressure resolution is 0.2kPa, and the measurement uncertainty is 0.005. The weight group configuration shown in this embodiment enables the test system of this application to fully cover the calibration requirements of pressure transmitter 4 under high static pressure conditions, while meeting the high precision requirements of differential pressure measurement.

[0030] In this embodiment, by setting a first piston assembly 1 and a second piston assembly 2, and configuring the gas path so that the first branch 302 connects to the low-pressure end 401 and the first piston assembly 1 of at least one pressure transmitter 4 under test, and the second branch 303 connects to the high-pressure end 402 and the second piston assembly 2 of at least one pressure transmitter 4 under test, by loading static pressure weights of the same mass onto the first piston assembly 1 and the second piston assembly 2, and by introducing high-pressure gas into the gas path, the first piston assembly 1 and the second piston assembly 2 are suspended, thereby generating the same static pressure at the low-pressure end 401 and the high-pressure end 402 of the pressure transmitter 4 under test, overcoming the limitation of the low-pressure end 401 being open to the atmosphere in the prior art. The method ignores the shortcomings of static pressure error. By setting an isolation shut-off valve 5 on the first branch 302, the connection between the first branch 302 and the intake passage 301 and the second branch 303 can be cut off after the same static pressure is established, so that the pressure at the low-pressure end 401 is locked. Then, by loading a differential pressure weight on the second piston assembly 2 and cooperating with the second pressure regulator assembly 7 to finely adjust, a precise micro differential pressure is generated. The differential pressure value is determined by the mass of the differential pressure weight. By comparing the differential pressure generated by the system with the reading of the pressure transmitter 4 under test as a standard value, the error between the reading and the standard value is calculated, and the error is compared with the preset allowable error range, so that the measurement accuracy of the pressure transmitter 4 under test can be evaluated and its qualification can be determined. This application realizes the accurate calibration of the micro differential pressure measurement accuracy of the pressure transmitter 4 under high static pressure environment, and provides a high-precision technical means for the static pressure error test of the pressure transmitter 4.

[0031] In an exemplary embodiment of this application, the test system further includes a gas source shut-off valve 10, which is disposed on the air inlet passage 301 and is used to switch the air inlet passage 301 on and off with a high-pressure gas source.

[0032] In this embodiment, the connection between the air intake passage 301 and the high-pressure air source is controlled by setting the air source shut-off valve 10. When the system starts testing, static pressure weights of the same mass are loaded on the first piston assembly 1 and the second piston assembly 2. At the same time, the air source shut-off valve 10 and the isolation shut-off valve 5 are opened to allow air to enter the air passage until the piston component 12 in the piston unit is in a suspended state. At the same time, the air source shut-off valve 10 and the isolation shut-off valve 5 are closed to lock the pressure in the air passage and disconnect the first branch 302 from the second branch 303. By loading a differential pressure weight on the second piston assembly 2 and using the second pressure regulator assembly 7 to regulate the pressure of the second piston assembly 2, the piston component 12 of the second piston assembly 2 is restored to a suspended state, so that the air pressure at the high-pressure end 402 of the pressure transmitter 4 under test is greater than the air pressure at the low-pressure end 401, thereby forming a differential pressure between the high-pressure end 402 and the low-pressure end 401 of the pressure transmitter 4 under test.

[0033] In an exemplary embodiment of this application, both the first piston assembly 1 and the second piston assembly 2 include a main body 11, a piston component 12, a buffer sleeve 13, a pressure cap 14, a tray 15, and a hanging basket 16; The main body 11 is provided with a guide part 1101, which is used to guide the piston component 12 to move along the axial direction of the main body 11; By providing a guide part 1101 on the main body 11, the piston component 12 is moved and guided along the axial direction, ensuring that the piston component 12 can move stably in a straight line under the push of gas pressure, and avoiding the piston component 12 from deflecting or getting stuck during the lifting and lowering process.

[0034] The main body 11 is also provided with an air inlet pipe 1102, an oil inlet pipe 1103, a manifold 1104, and a pressure discharge pipe 1105; the air outlet of the air inlet pipe 1102 corresponds to the manifold 1104, and the air pressure collected in the manifold 1104 is used to push the piston component 12 to move along the guide part 1101 so that the piston component 12 is in a suspended state; the oil outlet of the oil inlet pipe 1103 corresponds to the guide part 1101. By setting an air inlet pipe 1102 and an oil inlet pipe 1103 on the main body 11, and aligning the air outlet of the air inlet pipe 1102 with the manifold 1104 and the oil outlet of the oil inlet pipe 1103 with the guide section 1101, the functions of gas pressure generation and lubricating oil delivery are separated. The gas pressure acts on the manifold 1104 to push the piston component 12, while the lubricating oil is directly delivered to the guide section 1101 to lubricate the piston component 12, reducing the friction between the piston component 12 and the guide section 1101, and reducing the impact of friction on the static pressure simulation of the pressure transmitter 4.

[0035] The air outlet of the air intake pipe 1102 corresponds to the confluence area 1104. The air pressure collected in the confluence area 1104 directly acts on the bottom of the piston component 12. When the upward thrust generated by the air pressure is balanced with the total weight of the piston component 12, the tray 15, the hanging basket 16 and the loaded weight, the piston component 12 is in a suspended state.

[0036] The pressure relief pipeline 1105 is connected to the manifold 1104, and the pressure relief pipeline 1105 is used to discharge the gas and oil from the manifold 1104 to the main body 11. The pressure relief line 1105 is connected to the manifold 1104. After the test is completed, the residual gas and oil in the manifold 1104 can be discharged from the main body 11 through the pressure relief line 1105, which facilitates the maintenance and upkeep of the system and provides a pressure-free environment in the gas circuit for the next test condition.

[0037] The buffer sleeve 13 is fitted on the outside of the piston component 12, the pressure cap 14 is fitted on the outside of the buffer sleeve 13, the tray 15 is set on the top of the pressure cap 14, and the hanging basket 16 abuts against the tray 15. The buffer sleeve 13 provides cushioning and protection for the piston component 12, reducing the direct impact and wear between the piston component 12 and the pressure cap 14 during movement.

[0038] The tray 15 is provided with a first loading area 8 for loading differential pressure weights, and the hanging basket 16 is provided with a second loading area 9 for loading static pressure weights.

[0039] The load of the hanging basket 16 is transferred to the piston assembly 12 through the tray 15, ensuring that most of the load is located below the piston's center of gravity and that all loads are concentrated on the piston's vertical axis, thus improving the stability of pressure measurement.

[0040] In an exemplary embodiment of this application, the test system further includes a first pressure relief valve 17 and a second pressure relief valve 18. The first pressure relief valve 17 is connected to the pressure discharge line 1105 of the first piston assembly 1, and the second pressure relief valve 18 is connected to the pressure discharge line 1105 of the second piston assembly 2.

[0041] In this embodiment, by setting a first pressure relief valve 17 and a second pressure relief valve 18, which are respectively connected to the pressure relief pipelines 1105 of the first piston assembly 1 and the second piston assembly 2, the high-pressure gas and oil remaining in the piston assembly manifold 1104 can be quickly discharged after the test is completed or when maintenance is required. This achieves the rapid pressure relief function of the system and avoids safety hazards caused by high-pressure gas residue. At the same time, the setting of the pressure relief valve makes it easy to release the system pressure to the normal pressure state before replacing the static pressure weight or differential pressure weight, which improves the safety and convenience of the weight loading operation. In addition, the first pressure relief valve 17 and the second pressure relief valve 18 can be controlled independently, so that the two piston assemblies can be depressurized separately, which facilitates independent maintenance or troubleshooting of a single piston assembly.

[0042] In an exemplary embodiment of this application, the testing system further includes an oil cup 19, which includes a cup body, a plug, and an oil drain valve. The cup body is used to load lubricating oil, the plug is used to seal the cup body, and the oil drain valve is located at the bottom of the cup body and is used to drain the lubricating oil from the cup body. The cup body is equipped with a pressure balancing inlet and a lubricating oil outlet. The pressure balancing inlet is connected to a high-pressure air source, and the lubricating oil outlet is connected to the oil inlet pipe 1103.

[0043] In this embodiment, by setting a pressure balancing inlet and a lubricating oil outlet on the cup body of the oil cup 19, connecting the pressure balancing inlet to a high-pressure gas source, and connecting the lubricating oil outlet to the oil inlet pipe 1103 of the main body 11, high-pressure gas enters the gas chamber above the oil cup 19 and acts on the surface of the lubricating oil inside the cup, forcing the lubricating oil out and delivering it to the guide part 1101 of the piston assembly through the lubricating oil outlet. This achieves active lubrication of the piston assembly using system pressure, eliminating the need for an additional oil pump and reducing system costs. Furthermore, by setting an oil drain valve at the bottom of the cup body, it is easy to quickly drain the old oil inside the cup body when the lubricating oil needs to be replaced, reducing maintenance difficulty. By setting a plug to seal the cup body, the sealing performance of the oil cup 19 under high pressure environment is ensured, preventing lubricating oil leakage.

[0044] In an exemplary embodiment of this application, both the first pressure regulator assembly 6 and the second pressure regulator assembly 7 include a cylinder, a push rod, a lead screw, a handwheel, and a slotted cylinder; The cylinder is provided with an interface. The cylinder interface of the first pressure regulator assembly 6 is used to connect with the first branch 302, and the cylinder interface of the second pressure regulator assembly 7 is used to connect with the second branch 303. The push rod is located inside the cylinder, and the push rod and the cylinder are in transition fit; The slotted cylinder is connected to the cylinder, and the lead screw is threadedly connected to the slotted cylinder. One end of the lead screw, close to the cylinder along the axial direction, is connected to the push rod, and the other end is connected to the handwheel.

[0045] In this embodiment, the lead screw is threadedly connected to the slotted cylinder, and the push rod is located inside the cylinder and has a transition fit with the cylinder. The lead screw connects the push rod to the handwheel. By rotating the handwheel, the operator drives the lead screw to rotate, causing relative rotation between the lead screw and the slotted cylinder. This causes the lead screw to move axially, driving the push rod to move axially along the cylinder. The push rod compresses or expands the space inside the cylinder, thereby increasing or decreasing the gas pressure in the branch circuit, thus achieving gas pressure regulation. The transition fit between the push rod and the cylinder ensures that the push rod can move forward and backward within the cylinder and prevents gas from dispersing through the radial gap between the push rod and the cylinder. In the example, the pressure regulator assembly is configured such that the gas volume inside the cylinder changes by 0.27 cm³ for each rotation of the handwheel. This volume change allows the pressure regulator assembly to make extremely fine adjustments to the gas pressure inside the piston assembly, thereby ensuring that the piston component 12 can be precisely adjusted to a suspended state, providing a reliable means for the stable generation of micro differential pressure. By setting independent first pressure regulator assembly 6 and second pressure regulator assembly 7 to control the first piston assembly 1 and the second piston assembly 2 respectively, the pressure on both sides of the low-pressure end 401 and the high-pressure end 402 of the pressure transmitter 4 under test can be adjusted independently.

[0046] In an exemplary embodiment of this application, the cylinder is provided with a first mounting groove and a second mounting groove coaxially at one end away from the interface along the axial direction. The second mounting groove is used to install a sealing component, and the sealing component is used to seal the gap between the push rod and the second mounting groove. The first mounting groove is used to install a nut, which is sleeved on the push rod and is used to press the sealing component.

[0047] In this embodiment, a first mounting groove and a second mounting groove are coaxially arranged at the end of the cylinder furthest from the interface. The second mounting groove is used to install a sealing component. The sealing component seals the gap between the push rod and the second mounting groove, effectively preventing high-pressure gas in the cylinder from leaking outward along the gap between the push rod and the cylinder, thus ensuring the system's pressure holding capacity and the stability of pressure regulation. The first mounting groove is used to install a nut. The connection between the nut and the first mounting groove can be achieved by the nut having an external thread and the first mounting groove having an internal thread, with the nut and the first mounting groove being fixed by a threaded connection. The push rod passes through the nut and is connected to the lead screw. The nut presses the sealing component into the second mounting groove, providing a sealing preload for the sealing component and ensuring the sealing effect of the sealing component on the radial gap between the push rod and the second mounting groove. For example, the sealing component uses sealing filler to fill the radial gap between the push rod and the second mounting groove.

[0048] In an exemplary embodiment of this application, the sealing assembly includes a copper sleeve, which is disposed in the second mounting groove and sleeved on the push rod. The copper sleeve abuts against the bottom surface of the second mounting groove and the nut along the axial direction of the cylinder. A first sealing ring and a second sealing ring are sleeved on the copper sleeve, and the first sealing ring and the second sealing ring abut against the side wall of the second mounting groove. The end of the nut facing the copper sleeve has a sealing groove, and a third sealing ring is installed in the sealing groove. The third sealing ring is fitted onto the push rod.

[0049] In this embodiment, the sealing assembly includes a copper sleeve, a first sealing ring, a second sealing ring, and a third sealing ring. The copper sleeve is positioned within the second mounting groove and axially abuts against the bottom surface of the second mounting groove and the nut. This ensures the copper sleeve is pressed and fixed when the nut is locked into the first mounting groove, preventing loosening or displacement during use. By fitting the first and second sealing rings onto the copper sleeve and ensuring both rings abut against the sidewall of the second mounting groove, a double radial sealing structure is formed. This effectively prevents high-pressure gas from leaking outwards along the gap between the copper sleeve and the sidewall of the second mounting groove. Even if one sealing ring ages or is damaged, the other sealing ring maintains its sealing effect, improving sealing performance. This design enhances the reliability and redundancy of the seal. A sealing groove is provided at the end of the nut facing the copper sleeve, and a third sealing ring, fitted onto the push rod, is placed within this groove. The third sealing ring is positioned axially between the copper sleeve and the nut. Through the abutting contact between the copper sleeve and the nut, the third sealing ring is deformed, thus sealing the gap between the nut and the copper sleeve abutting surface. This further prevents high-pressure gas from leaking outwards along the abutting gap between the copper sleeve and the nut. The rigid support of the copper sleeve and the elastic sealing effect of the three sealing rings work together to form multiple sealing barriers between the push rod and the cylinder, significantly improving the sealing performance of the pressure regulator assembly under high static pressure conditions and ensuring the stability of pressure regulation and the system's pressure-holding capacity.

[0050] Please combine Figure 5 As shown, the present invention also provides a method for testing the static pressure error of a pressure transmitter. Figure 2 This is a flowchart illustrating the static pressure error test method for pressure transmitters as shown in this application.

[0051] In an exemplary embodiment of this application, a static pressure error testing method for a pressure transmitter includes the static pressure error testing system for a pressure transmitter as described above. The testing method includes at least steps S110 to S150, which are detailed below: In step S110, a static pressure weight corresponding to a preset static pressure is loaded onto the hanging basket 16 of the first piston assembly 1 and the second piston assembly 2.

[0052] For example, by loading a static pressure weight corresponding to a preset static pressure onto the hanging basket 16 of the first piston assembly 1 and the second piston assembly 2, a standard value of static pressure is provided for the system. The mass of the static pressure weight determines the magnitude of the static pressure generated by the system.

[0053] In step S120, the first pressure relief valve 17 and the second pressure relief valve 18 are closed, and the air source shut-off valve 10 and the isolation shut-off valve 5 are opened. The high-pressure air source enters the system through the air inlet passage 301, and is distributed to the low-pressure end 401 of the first piston assembly 1 and the pressure transmitter 4 through the first branch 302, and distributed to the high-pressure end 402 of the second piston assembly 2 and the pressure transmitter 4 through the second branch 303, until the internal air pressure of the first piston assembly 1 and the second piston assembly 2 lifts the piston component 12 to a suspended state.

[0054] For example, by closing the first pressure relief valve 17 and the second pressure relief valve 18, and opening the air source shut-off valve 10 and the isolation shut-off valve 5, high-pressure air enters the system through the air inlet passage 301. It is then distributed via the first branch 302 to the low-pressure end 401 of the first piston assembly 1 and the pressure transmitter 4, and via the second branch 303 to the high-pressure end 402 of the second piston assembly 2 and the pressure transmitter 4, until the internal air pressure of the two piston assemblies lifts the piston component 12 into a suspended state. This step ensures that both ends of the pressure transmitter 4 are simultaneously subjected to the same static pressure, realistically simulating the static pressure environment of the pressure transmitter 4 in actual operation, overcoming the defect in the prior art where the low-pressure end 401 is vented to the atmosphere, thus ignoring static pressure error. When the piston component 12 is in a suspended state, the internal pressure of the system is precisely equal to the pressure value generated by the static pressure weight, ensuring the accuracy of the static pressure.

[0055] In step S130, the gas source shut-off valve 10 and the isolation shut-off valve 5 are closed, and a differential pressure weight corresponding to the preset differential pressure is loaded on the tray 15 of the second piston assembly 2.

[0056] For example, by closing the gas source shut-off valve 10 and the isolation shut-off valve 5, the connection between the first branch 302 and the air intake passage 301 and the second branch 303 is cut off, so that the pressure at the low-pressure end 401 and the pressure at the high-pressure end 402 are both locked; by loading a differential pressure weight corresponding to the preset differential pressure on the tray 15 of the second piston assembly 2, when the second pressure regulating component adjusts the second piston assembly 2 to return to suspension, a stable differential pressure can be formed on both sides of the high-pressure end 402 and the low-pressure end 401 of the pressure transmitter 4 under test.

[0057] In step S140, the air pressure inside the second piston assembly 2 is adjusted by the second pressure regulator assembly 7, so that the piston component 12 inside the second piston assembly 2 returns to a suspended state.

[0058] For example, due to the loading of the differential pressure weight, the second piston assembly 2 requires a higher gas pressure to balance the gravity. Therefore, the pressure of the second piston assembly 2 increases and becomes higher than that of the first piston assembly 1, thereby generating a differential pressure between the first piston assembly 1 and the second piston assembly 2. This differential pressure value is determined by the mass of the differential pressure weight and does not depend on electronic sensors, thus avoiding the problem of decreased differential pressure measurement accuracy under high static pressure.

[0059] In step S150, the differential pressure reading of the pressure transmitter 4 under test is compared with the preset differential pressure, and the error between the differential pressure reading and the preset differential pressure is calculated. If the error is within the preset allowable error range, the pressure transmitter 4 under test is determined to be qualified. If the error exceeds the preset allowable error range, the pressure transmitter 4 under test is determined to be unqualified.

[0060] For example, the standard differential pressure value generated by the system is quantitatively compared with the actual reading of the pressure transmitter 4 under test, which quantifies the measurement deviation of the transmitter and provides a basis for qualification judgment. If the actual reading error of the pressure transmitter 4 under test is within the preset allowable error range, the pressure transmitter 4 under test is judged to be qualified; if the error exceeds the preset allowable error range, it is judged to be unqualified.

[0061] In this embodiment, the static pressure error testing method for pressure transmitters disclosed in this application achieves accurate calibration of the micro differential pressure measurement accuracy of pressure transmitter 4 under high static pressure environment through the process of static pressure establishment, internal air pressure isolation and locking, differential pressure establishment, reading comparison and qualification judgment. It provides a systematic and standardized operation process for static pressure error testing of pressure transmitter 4, and has the advantages of simple operation and reliable results.

[0062] In an exemplary embodiment of this application, the static pressure error test method for a pressure transmitter further includes: loading a differential pressure weight with a preset differential pressure onto the tray 15 of the first piston assembly 1; adjusting the air pressure inside the first piston assembly 1 through the first pressure regulator assembly 6 to restore the piston component 12 inside the first piston assembly 1 to a suspended state; generating a reverse differential pressure between the low-pressure end 401 and the high-pressure end 402 of the pressure transmitter 4 under test; reading the reading of the pressure transmitter 4 under test and comparing it with the preset differential pressure.

[0063] In this embodiment, by loading a differential pressure weight with a preset differential pressure onto the tray 15 of the first piston assembly 1, and by using the first pressure regulator assembly 6 to adjust the air pressure inside the first piston assembly 1 to restore the piston component 12 to a suspended state, a reverse differential pressure opposite to the forward differential pressure is generated between the low-pressure end 401 and the high-pressure end 402 of the pressure transmitter under test 4, thus realizing the test of the reverse differential pressure measurement performance of the pressure transmitter under test 4. The combination of reverse differential pressure test and forward differential pressure test can comprehensively verify the measurement consistency of the pressure transmitter under test 4 in both directions and detect whether the transmitter has zero drift or unidirectional error. By comparing the results of the reverse differential pressure test with those of the forward differential pressure test, if the errors in both directions are basically the same and within the preset allowable error range, it indicates that the bidirectional symmetry of the pressure transmitter 4 under test is good. If the reverse error is significantly greater than the forward error, it indicates that the pressure transmitter 4 under test has structural or assembly asymmetry problems. The reverse differential pressure test provides a bidirectional testing method for the comprehensive performance evaluation of the pressure transmitter 4 under test, and is particularly suitable for industrial sites that require bidirectional differential pressure measurement, such as bidirectional flow measurement, ensuring that the pressure transmitter 4 under test can maintain accurate measurement accuracy regardless of the direction of the differential pressure in actual applications.

[0064] In another embodiment, damping valves 20 are provided on the gas paths of both the high-pressure end 402 and the low-pressure end 401 of the pressure transmitter 4 under test. The damping valves 20 are used to limit the gas flow rate and suppress the pressure surge at the moment of gas intake, thereby protecting the sensitive elements inside the pressure transmitter 4 under test.

[0065] The damping valve 20 includes a knurled nut 2001, a gauge rod 2002, a valve body 2003, a CNC ring 2004, a copper washer 2005, a stepped copper washer 2006, a valve needle 2007, and a hexagonal clamping nut 2008. The valve body 2003 is made of stainless steel and has a through-flow air inlet and outlet path. A vertically mounted valve needle 2007 is located in the middle of the valve body 2003, intersecting with the main airflow channel to form a variable throttling orifice. The valve needle 2007 is a precision-machined needle-shaped rod with a taper at its front end that matches the valve seat hole on the valve body 2003. The valve needle 2007 is threaded onto the upper part of the valve body 2003. Rotating the valve needle 2007 changes its depth into the valve body 2003 hole, thereby changing the airflow cross-sectional area and achieving continuous airflow regulation. A handle 2009 is located at the rear end of the valve needle 2007 for easy operation. To prevent high-pressure gas from leaking outwards along the valve needle 2007, a multi-stage combined sealing unit is installed between the valve needle 2007 and the valve body 2003. From the inside out, the unit consists of: a stepped copper gasket 2006 installed on the outermost side, tightly fitting against the valve needle 2007, providing primary sealing and guiding; a copper washer 2005 located inside the stepped copper gasket 2006, assisting in forming a metal seal; and a Chevron ring 2004 with two O-rings on the outside, installed inside the copper washer 2005, tightly fitting against the bottom of the valve needle 2007. The Chevron ring 2004, under the preload of the O-rings, grips the valve needle 2007, providing an elastically compensated seal suitable for dynamic reciprocating motion. These sealing components are sequentially installed into the sealing groove of the valve body 2003 and preloaded by the hexagonal compression nut 2008, ensuring reliable sealing under 50MPa pressure.

[0066] When establishing static pressure conditions, damping valve 20 should be in the open position. When establishing lower static pressures, the valve opening can be appropriately increased to balance response speed and buffering effect; when establishing higher static pressures, the valve opening should be controlled to limit the intake air flow, preventing overpressure damage to the transmitter due to rapid gas compression or impact. Furthermore, gas pressure often fluctuates, with instantaneous pressure peaks potentially reaching several times the rated pressure, easily damaging the sensor. Damping valve 20 effectively weakens pressure peaks, acting as a pressure-shaving and stabilizing agent, ensuring a smooth rise in the pressure curve and guaranteeing safe testing and accurate measurement results.

[0067] In another exemplary embodiment, the piston component 12 is suspended at the midpoint of its travel stroke, which is the zero position. When static pressure is established, air is introduced into the system so that the piston components 12 of both the first piston assembly 1 and the second piston assembly 2 are in a zero-position suspension state. The isolation shut-off valve 5 is closed to establish differential pressure. When the error between the piston component 12 and the zero position is within ±0.25mm, the differential pressure zero-point data is recorded, and the pressure reading can be obtained.

[0068] It is worth noting that, in order to achieve high-precision real-time monitoring of the position of the piston component 12 in the system, this embodiment provides a displacement detection device, including: a high-pressure end support 21, a low-pressure end support 22, a high-pressure end ranging sensor 23, a low-pressure end ranging sensor 24, and a display 25. The high-pressure end ranging sensor 23 is mounted on the high-pressure end support 21 and is used to monitor the position height of the piston component 12 in the second piston assembly 2; the low-pressure end ranging sensor 24 is mounted on the low-pressure end support 22 and is used to monitor the position height of the piston component 12 in the first piston assembly 1; the high-pressure end ranging sensor 23 and the low-pressure end ranging sensor 24 transmit the data of the piston component 12 to the analysis software in real time, and after calculation, the results are displayed on the display 25, allowing the operator to observe the operating status of the system in real time. By setting up the displacement detection device, the displacement, direction of movement, descent speed, and duration of the piston component 12 in the first piston assembly 1 and the second piston assembly 2 can be detected and graphically displayed in real time.

[0069] For example, the high-voltage end ranging sensor 23 and the low-voltage end ranging sensor 24 include, but are not limited to, laser ranging sensors using triangulation to detect the displacement of the piston component 12 in real time. The measurement range covers 100mm ± 30mm (i.e., the range can reach 0~60mm), with a resolution as high as 0.01mm. The accuracy and sensitivity are significantly better than traditional projection devices. It supports simultaneous detection of the displacement trajectories of the first piston assembly 1 and the second piston assembly 2, and displays the motion state and direction of the piston component 12 in real time on the touch screen in the form of curves. The interface is intuitive and easy to operate. Equipped with a speed sensor, it automatically measures the duration of the piston component 12; the laser ranging sensor can also monitor the descent speed of the piston component 12 to help judge the smoothness of the piston component 12's movement. The display 25 has a built-in piston component 12 area calculation program, which can complete the necessary data processing on site; it supports exporting calibration records via USB interface or directly connecting to a printer to print calibration records. The laser rangefinder outputs an analog signal (0~5V) to the data acquisition unit; the rotation speed sensor outputs a digital signal to the data acquisition unit; the data acquisition unit is connected to the host computer via an RS232 interface to ensure stable signal transmission.

[0070] The working principle of this application is detailed as follows: First, the isolation shut-off valve 5 is opened to connect the first branch 302 with the air inlet passage 301. Static pressure weights of the same mass are loaded onto the hanging basket 16 of the first piston assembly 1 and the second piston assembly 2. The air source shut-off valve 10 is opened, and the high-pressure air source enters the first piston assembly 1, the second piston assembly 2, and the low-pressure end 401 and high-pressure end 402 of the pressure transmitter 4 through the air inlet passage 301, the first branch 302, and the second branch 303. The first pressure regulator assembly 6 and the second pressure regulator group are then operated. Component 7 adjusts the gas pressure in the two piston assemblies respectively until both piston components 12 are lifted into a suspended state. At this time, the pressure generated by the two piston assemblies is equal, and the two ends of the pressure transmitter 4 are subjected to the same static pressure, with zero differential pressure. Then, the gas source shut-off valve 10 and the isolation shut-off valve 5 are closed to disconnect the system from the high-pressure gas source and the connection between the first branch 302 and the air inlet passage 301 and the second branch 303, so that the low-pressure end 401 of the first piston assembly 1 and the pressure transmitter 4, and the second piston assembly 2 and the pressure transmitter 4 are connected. The pressure at the high-pressure end 402 of the pressure transmitter 4 is locked. By loading a differential pressure weight onto the tray 15 of the second piston assembly 2, the second pressure regulator assembly 7 is operated to compress the gas inside the second piston assembly 2, increasing the pressure until the piston component 12 of the second piston assembly 2 returns to a suspended state. At this time, the pressure of the second piston assembly 2 is higher than that of the first piston assembly 1, generating a positive differential pressure corresponding to the differential pressure weight across the pressure transmitter 4. If a reverse differential pressure is required, a differential pressure weight is loaded onto the tray 15 of the first piston assembly 1, and the first pressure regulator assembly 6 is operated to restore the piston component of the first piston assembly 1 to a suspended state, making the pressure of the first piston assembly 1 higher than that of the second piston assembly 2, generating a reverse differential pressure. Finally, the differential pressure reading of the pressure transmitter 4 is read and compared with the standard differential pressure value generated by the differential pressure weight. The error is calculated. If the error is within the preset allowable error range, it is considered qualified; otherwise, it is considered unqualified. By changing the mass combination of the static pressure weight and the differential pressure weight, different static pressure conditions and different differential pressure points can be generated, realizing comprehensive testing of multiple static pressure conditions and multiple differential pressure points.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A static pressure error testing system for a pressure transmitter, comprising a pressure transmitter under test, wherein the pressure transmitter under test includes a low-pressure end and a high-pressure end, characterized in that, The testing system includes: The piston unit includes a first piston assembly and a second piston assembly; The gas path includes an air inlet passage, a first branch, and a second branch; the air inlet passage is used to connect to a high-pressure gas source, and the first branch and the second branch are respectively connected to the air inlet passage; the first branch is connected to the low-pressure end of at least one pressure transmitter under test, and the first branch is connected to the first piston assembly; the second branch is connected to the high-pressure end of at least one pressure transmitter under test, and the second branch is connected to the second piston assembly. An isolation shut-off valve is installed on the first branch and is used to cut off or connect the first branch with the air intake passage. A first pressure regulator assembly is disposed on the first branch and located between the isolation shut-off valve and the first piston assembly. The first pressure regulator assembly is used to regulate the gas pressure in the first piston assembly. A second pressure regulator assembly is disposed on the second branch, and the second pressure regulator assembly is used to regulate the gas pressure in the second piston assembly; The weight set includes static pressure weights and differential pressure weights; the static pressure weights are used to load the first piston assembly and the second piston assembly to generate the same static pressure across the pressure transmitter under test; the differential pressure weights are used to load the first piston assembly or the second piston assembly to generate a differential pressure across the pressure transmitter under test.

2. The static pressure error testing system for pressure transmitters according to claim 1, characterized in that: The testing system also includes a gas source shut-off valve, which is installed on the air intake passage and is used to connect or disconnect the air intake passage from the high-pressure gas source.

3. The static pressure error testing system for pressure transmitters according to claim 2, characterized in that: Both the first piston assembly and the second piston assembly include a main body, piston components, a buffer sleeve, a pressure cap, a tray, and a hanging basket; The main body is provided with a guide portion, which is used to guide the piston component to move along the axial direction of the main body; The main body is also provided with an air intake pipe, an oil intake pipe, a manifold, and a pressure discharge pipe; The air outlet of the air inlet pipe corresponds to the confluence area, and the air pressure collected in the confluence area is used to push the piston component to move along the guide portion so that the piston component is in a suspended state; The oil outlet of the oil inlet pipe corresponds to the guide section; The pressure relief pipeline is connected to the manifold, and the pressure relief pipeline is used to discharge the gas and oil from the manifold to the main body; The buffer sleeve is fitted on the outside of the piston component, the pressure cap is fitted on the outside of the buffer sleeve, the tray is disposed on the top of the pressure cap, and the hanging basket abuts against the tray; The tray is used to load differential pressure weights, and the hanging basket is used to load static pressure weights.

4. The static pressure error testing system for pressure transmitters according to claim 3, characterized in that: The testing system also includes a first pressure relief valve and a second pressure relief valve. The first pressure relief valve is connected to the pressure discharge line of the first piston assembly, and the second pressure relief valve is connected to the pressure discharge line of the second piston assembly.

5. The static pressure error testing system for pressure transmitters according to claim 3, characterized in that: The testing system also includes an oil cup, which includes a cup body, a plug, and an oil drain valve. The cup body is used to hold lubricating oil, the plug is used to seal the cup body, and the oil drain valve is located at the bottom of the cup body and is used to drain the lubricating oil from the cup body. The cup body is provided with a pressure balancing inlet and a lubricating oil outlet. The pressure balancing inlet is connected to a high-pressure air source, and the lubricating oil outlet is connected to the oil inlet pipe.

6. The static pressure error testing system for pressure transmitters according to claim 3, characterized in that: Both the first pressure regulator assembly and the second pressure regulator assembly include a cylinder, a push rod, a lead screw, a handwheel, and a slotted cylinder; The cylinder is provided with an interface, the cylinder interface of the first pressure regulator assembly is used to communicate with the first branch, and the cylinder interface of the second pressure regulator assembly is used to communicate with the second branch. The push rod is located inside the cylinder, and the push rod is in transition fit with the cylinder; The slotted cylinder is connected to the cylinder, the lead screw is threaded to the slotted cylinder, one end of the lead screw axially close to the cylinder is connected to the push rod, and the other end is connected to the handwheel.

7. The static pressure error testing system for pressure transmitters according to claim 6, characterized in that: The cylinder is provided with a first mounting groove and a second mounting groove on one end axially away from the interface. The second mounting groove is used to install a sealing component, which is used to seal the gap between the push rod and the second mounting groove. The first mounting groove is used to install a nut, which is sleeved on the push rod and is used to press the sealing component.

8. The static pressure error testing system for pressure transmitters according to claim 7, characterized in that: The sealing assembly includes a copper sleeve, which is disposed in the second mounting groove and sleeved on the push rod. The copper sleeve abuts against the bottom surface of the second mounting groove and the nut along the axial direction of the cylinder. A first sealing ring and a second sealing ring are sleeved on the copper sleeve, and the first sealing ring and the second sealing ring abut against the side wall of the second mounting groove. The nut has a sealing groove at one end facing the copper sleeve, and a third sealing ring is provided in the sealing groove. The third sealing ring is sleeved on the push rod.

9. A method for testing the static pressure error of a pressure transmitter, comprising the static pressure error testing system for a pressure transmitter as described in any one of claims 3-8, characterized in that, The method includes: By loading static pressure weights corresponding to a preset static pressure onto the hanging baskets of the first piston assembly and the second piston assembly; Close the first pressure relief valve and the second pressure relief valve, open the air source shut-off valve and the isolation shut-off valve, and the high-pressure air source enters the system through the air inlet passage. It is distributed to the low-pressure end of the first piston assembly and the pressure transmitter through the first branch, and distributed to the high-pressure end of the second piston assembly and the pressure transmitter through the second branch, until the internal air pressure of the first piston assembly and the second piston assembly lifts the piston component to a suspended state. Close the gas source shut-off valve and the isolation shut-off valve, and load a differential pressure weight corresponding to the preset differential pressure onto the tray of the second piston assembly; The air pressure inside the second piston assembly is adjusted by the second pressure regulator assembly, so that the piston component inside the second piston assembly returns to a suspended state. The differential pressure reading of the pressure transmitter under test is compared with the preset differential pressure. The error between the differential pressure reading and the preset differential pressure is calculated. If the error is within the preset allowable error range, the pressure transmitter under test is deemed qualified. If the error exceeds the preset allowable error range, the pressure transmitter under test is deemed unqualified.

10. The method for testing the static pressure error of a pressure transmitter according to claim 9, characterized in that, The method further includes: A differential pressure weight with a preset differential pressure is loaded onto the tray of the first piston assembly. The air pressure inside the first piston assembly is adjusted by the first pressure regulator assembly, so that the piston component inside the first piston assembly returns to a suspended state. A reverse differential pressure is generated between the low-pressure end and the high-pressure end of the pressure transmitter under test. The reading of the pressure transmitter under test is read and compared with the preset differential pressure.

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