Low-temperature and low-pressure safety valve testing device

Abstract

This invention relates to the field of safety valve testing technology, specifically a cryogenic and low-pressure safety valve testing device. The device includes a cryogenic testing flange, with a safety valve to be tested detachably mounted on the top of the flange. A liquid nitrogen inlet channel is provided on one side of the flange, and a hollow tube is vertically installed in the middle of the flange. One end of the liquid nitrogen inlet channel is connected to the hollow tube, and the other end is connected to a Dewar flask interface. The upper end of the hollow tube extends into the bottom valve seat cavity of the safety valve to be tested. A liquid nitrogen outlet channel is provided on the other side of the flange, with a test connector installed at one end and the other end connected to the valve seat cavity. In this cryogenic and low-pressure safety valve testing device, the device is directly connected to a liquid nitrogen supply source via the Dewar flask interface, eliminating the need for a large cryogenic pressure vessel. The hollow tube precisely delivers liquid nitrogen to the valve seat cavity of the safety valve to be tested, reducing ineffective losses during transmission.

Description

Technical Field

[0001] This invention relates to the field of safety valve testing technology, and more specifically, to a low-temperature, low-pressure safety valve testing device. Background Technology

[0002] In industrial fields such as aerospace, liquefied natural gas, and cryogenic refrigeration, cryogenic safety valves are critical components ensuring the safe operation of systems. The accuracy of their set pressure, sealing performance, and other indicators directly affects the safety of equipment and operators. Therefore, cryogenic safety valves must undergo rigorous cryogenic environmental testing before leaving the factory or during periodic calibration to simulate their performance under actual working conditions.

[0003] Currently, the industry primarily uses large cryogenic pressure vessels as testing platforms for cryogenic safety valves. These devices typically require injecting a large amount of liquid nitrogen into the pressure vessel to create a cryogenic environment before installing the safety valve under test at the vessel's interface. However, this traditional testing method has significant drawbacks: Firstly, large pressure vessels generally have large volumes. For example, a 0.6 cubic meter vessel requires at least 1.8 cubic meters of liquid nitrogen per test to meet the cryogenic environment requirements. Based on market prices, the cost of liquid nitrogen per test can exceed 3600 yuan. Furthermore, if the vessel is only half-filled with liquid nitrogen, the large volume causes rapid vaporization, making it difficult to maintain a stable cryogenic environment and resulting in extremely low liquid nitrogen utilization. Secondly, for safety valve manufacturers, the testing frequency for cryogenic safety valves is low; most companies only need to conduct a dozen or so tests per year. The liquid nitrogen in a large pressure vessel will be completely consumed by vaporization within 2-3 days, leading to severe resource waste and cost burden. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature and low-pressure safety valve testing device to solve the problem mentioned in the background art, which is that due to the large volume, the liquid nitrogen vaporization rate is fast and it is difficult to maintain a stable low-temperature environment, resulting in extremely low liquid nitrogen utilization.

[0005] To achieve the above objectives, the present invention provides a low-temperature, low-pressure safety valve testing device, comprising a low-temperature testing flange, on the top of which a safety valve to be tested is detachably mounted; a liquid nitrogen inlet channel is provided on one side of the low-temperature testing flange; a hollow tube is vertically mounted in the middle of the low-temperature testing flange; one end of the liquid nitrogen inlet channel is connected to the hollow tube; a Dewar flask interface is installed at the other end of the liquid nitrogen inlet channel; the upper end of the hollow tube extends into the bottom valve seat cavity of the safety valve to be tested; a liquid nitrogen outlet channel is provided on the other side of the low-temperature testing flange; a test connector is installed at one end of the liquid nitrogen outlet channel; and the other end of the liquid nitrogen outlet channel is connected to the valve seat cavity.

[0006] This setup connects the Dewar flask interface to the hollow tube via a cryogenic pressure testing flange. Liquid nitrogen is introduced through the Dewar flask interface, entering the hollow tube through the liquid nitrogen inlet channel, and then being delivered to the valve seat cavity of the safety valve under test, simulating a cryogenic environment. Simultaneously, a liquid nitrogen outlet channel is provided, one end connected to the valve seat cavity and the other end connected to a testing connector, used to discharge liquid nitrogen from the valve seat cavity and monitor relevant parameters, thus constructing a complete cryogenic medium circulation and testing pathway.

[0007] As a preferred embodiment of the present invention, the length of the upper part of the hollow tube extending out of the low-temperature pressure test flange is less than the height of the valve seat cavity.

[0008] This setting ensures that the length of the hollow tube extending beyond the cryogenic test flange is less than the height of the valve seat cavity. This prevents the hollow tube from excessively occupying the space inside the valve seat cavity, allowing sufficient space for the valve seat cavity to hold liquid nitrogen without hindering the flow and distribution of liquid nitrogen within the valve seat cavity. This ensures that the valve seat cavity can fully play its role in cryogenic environment simulation.

[0009] As a preferred embodiment of the present invention, the top of the low-temperature pressure testing flange is provided with a plurality of bolt fixing holes, which are connected and fixed to the safety valve to be tested by bolts.

[0010] This feature includes bolt fixing holes on the top of the low-temperature test flange, which is then connected and fixed to the safety valve under test via bolts. This bolt connection provides a detachable and stable mechanical connection between the low-temperature test flange and the safety valve under test, facilitating the replacement of different specifications of safety valves according to different testing requirements.

[0011] As a preferred embodiment of the present invention, the liquid nitrogen inlet channel is provided with a vertical internal thread at one end near the hollow tube, and the lower end of the hollow tube is provided with an external thread, and the internal thread is threadedly connected to the lower end of the hollow tube.

[0012] This design features an internal thread at one end of the liquid nitrogen inlet channel near the hollow tube, and an external thread at the lower end of the hollow tube. The two are connected by threads, enabling a detachable connection between the liquid nitrogen inlet channel and the hollow tube. This connection effectively ensures a tight seal and prevents liquid nitrogen leakage.

[0013] As a preferred embodiment of the present invention, an overflow channel is provided in the middle of the top of the low-temperature pressure testing flange, the hollow tube passes vertically through the overflow channel, the diameter of the overflow channel is larger than the outer diameter of the hollow tube, the upper end of the overflow channel is connected to the inner cavity of the valve seat, and the lower end of the overflow channel is connected to the liquid nitrogen outlet channel.

[0014] This design incorporates an overflow channel in the center of the top of the cryogenic pressure testing flange. A hollow tube passes vertically through this channel, with the overflow channel's diameter exceeding the outer diameter of the hollow tube. The upper end of the overflow channel connects to the valve seat's inner cavity, while the lower end connects to the liquid nitrogen outlet channel. When there is excessive liquid nitrogen or excessive pressure within the valve seat's inner cavity, liquid nitrogen can flow through the overflow channel into the liquid nitrogen outlet channel, thus regulating the amount and pressure of liquid nitrogen within the valve seat's inner cavity.

[0015] As a preferred embodiment of the present invention, a pressure gauge is installed on the detection connector, and a vent valve is installed on the connecting pipe of the pressure gauge.

[0016] This setting involves installing a pressure gauge on the test connector to monitor the pressure inside the valve seat cavity in real time. A vent valve is installed on the pressure gauge connection line. When the pressure is too high, some gas can be released through the vent valve to regulate the pressure. By using the pressure monitoring and regulation device, precise control of the pressure inside the valve seat cavity can be achieved.

[0017] As a preferred embodiment of the present invention, an exhaust pipe is installed at the outer end of the detection connector, a three-way pipe is installed at the outer end of the exhaust pipe, a temperature measuring port is provided at one end of the three-way pipe, and a gas mass flow meter is connected to the upper end of the three-way pipe.

[0018] This device is configured such that the outer end of the test connector is sequentially connected to an exhaust pipe and a tee pipe. One end of the tee pipe has a temperature measuring port, and the upper interface is connected to a gas mass flow meter. When the safety valve is opened, the discharged gas flows through the exhaust pipe and the tee pipe. The temperature sensor connected to the temperature measuring port can measure the gas temperature, while the gas mass flow meter is used to measure the gas flow rate, thereby obtaining the key parameters of the gas discharged after the safety valve is opened.

[0019] As a preferred embodiment of the present invention, the temperature measuring port is connected to an external temperature sensor for gas temperature measurement.

[0020] This device connects to an external temperature sensor at the temperature measuring port. Based on the thermosensitive characteristics of the temperature sensor, it senses the temperature of the gas flowing through the measuring port in real time and converts the temperature signal into an electrical signal for output, thereby realizing the measurement of the gas temperature.

[0021] As a preferred embodiment of the present invention, a switching valve is installed on the connecting pipeline of the gas mass flow meter, and the gas mass flow meter is used to measure the gas flow rate.

[0022] This setting involves installing a switch valve on the gas mass flow meter connection line to control the on / off state of the gas mass flow meter. When gas flow needs to be measured, the switch valve is opened, and gas flows through the gas mass flow meter. Utilizing the internal sensing element of the gas mass flow meter, the gas flow rate data is measured and output based on the effect of the gas flow on the sensing element.

[0023] As a preferred embodiment of the present invention, the detection connector is threadedly connected to the liquid nitrogen outlet channel and the detection connector is threadedly connected to the exhaust pipe, and a sealing tape is installed at the connection.

[0024] This setup uses threaded connections between the test connector, the liquid nitrogen outlet channel, and the exhaust pipe, with sealing tape installed at the connection points. The tightness of the threaded connections and the sealing effect of the sealing tape ensure the airtightness of the connection between the test connector and the liquid nitrogen outlet channel and exhaust pipe, preventing gas or liquid nitrogen leakage.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this cryogenic and low-pressure safety valve testing device, the device is directly connected to the liquid nitrogen supply source via a Dewar flask interface, eliminating the need for large cryogenic pressure vessels. Liquid nitrogen is precisely delivered to the valve seat cavity of the safety valve under test using a hollow tube, reducing ineffective losses during transmission. Simultaneously, for small- to medium-batch testing needs, it avoids resource waste caused by liquid nitrogen vaporization in large containers, significantly reducing testing costs for enterprises.

[0026] 2. In this low-temperature, low-pressure safety valve testing device, liquid nitrogen is directly injected into the valve seat cavity through a hollow tube, directly contacting the sealing surface of the safety valve under test, thus shortening the low-temperature conduction path. Furthermore, the coordinated design of the overflow channel and the liquid nitrogen outlet channel allows for the rapid discharge of gaseous nitrogen from the cavity, preventing gas stagnation from affecting low-temperature stability and ensuring the formation of a low-temperature environment that meets testing requirements within a short time, thereby improving the efficiency of a single test.

[0027] 3. In this low-temperature, low-pressure safety valve testing device, the overall structure is designed to withstand pressures suitable for the pressure range of domestic Dewar flasks, especially for testing low-pressure safety valves below 2.5 MPa. The pressure gauge on the testing connector allows for real-time monitoring of the valve seat cavity pressure, enabling precise pressure control in conjunction with the venting valve. Simultaneously, the gas mass flow meter connected to the three-way pipe accurately measures the gas flow rate after the safety valve opens. Combined with temperature monitoring data from the temperature measuring port, this provides precise parameters for evaluating key indicators such as set pressure and sealing performance, achieving testing accuracy comparable to that of large pressure vessels. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2 This is a partial top view of the structure of the present invention.

[0030] Figure 3 This is a schematic diagram of the detection connector in this invention.

[0031] Figure 4 This is a schematic diagram of the exhaust pipe structure in this invention.

[0032] Figure 5 For the present invention Figure 1 A magnified view of a portion of point A in the middle.

[0033] The meanings of the labels in the diagram are as follows: 1. Low-temperature pressure testing flange; 11. Liquid nitrogen inlet channel; 12. Liquid nitrogen outlet channel; 13. Bolt fixing hole; 14. Overflow channel; 15. Internal thread port; 2. Dewar canister interface; 3. Hollow tube; 4. Safety valve to be tested; 41. Valve seat cavity; 5. Test connector; 6. Pressure gauge; 61. Vent valve; 7. Exhaust pipe; 8. T-connector; 81. Temperature measuring port; 9. Gas mass flow meter; 91. Switch valve. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] This invention provides a low-temperature, low-pressure safety valve testing device, such as... Figure 1 As shown, the device includes a cryogenic test flange 1, a safety valve 4 to be tested is detachably installed on the top of the cryogenic test flange 1, a liquid nitrogen inlet channel 11 is provided on one side of the cryogenic test flange 1, a hollow tube 3 is vertically installed in the middle of the cryogenic test flange 1, one end of the liquid nitrogen inlet channel 11 is connected to the hollow tube 3, the other end of the liquid nitrogen inlet channel 11 is installed with a Dewar canister interface 2, the upper end of the hollow tube 3 extends into the bottom valve seat cavity 41 of the safety valve 4 to be tested, a liquid nitrogen outlet channel 12 is provided on the other side of the cryogenic test flange 1, a test connector 5 is installed at one end of the liquid nitrogen outlet channel 12, and the other end of the liquid nitrogen outlet channel 12 is connected to the valve seat cavity 41.

[0036] The Dewar flask interface 2 is connected to the hollow tube 3 via the cryogenic testing flange 1. Liquid nitrogen is introduced through the Dewar flask interface 2, and then enters the hollow tube 3 through the liquid nitrogen inlet channel 11. From there, it is transported to the valve seat cavity 41 of the safety valve 4 under test, simulating a cryogenic environment. Simultaneously, a liquid nitrogen outlet channel 12 is provided, with one end connected to the valve seat cavity 41 and the other end connected to the testing connector 5. This outlet channel is used to discharge the liquid nitrogen from the valve seat cavity 41 and monitor relevant parameters, thus establishing a complete cryogenic medium circulation and testing pathway. This method utilizes the Dewar flask as a liquid nitrogen supply source to directly provide a cryogenic testing environment for the safety valve 4 under test, avoiding the use of large cryogenic pressure vessels and significantly reducing testing costs. Compared to traditional large-container testing methods, the liquid nitrogen consumption per test can be reduced by more than 80%. Moreover, this structure allows for rapid delivery of liquid nitrogen to key parts of the valve seat cavity 41, increasing the cooling rate by more than 50% compared to traditional devices, significantly improving testing efficiency.

[0037] In this embodiment, as Figure 1 As shown, the length of the upper part of the hollow tube 3 extending out of the low-temperature test flange 1 is less than the height of the valve seat cavity 41.

[0038] The length of the hollow tube 3 extending beyond the cryogenic test flange 1 is less than the height of the valve seat cavity 41. This ensures that the hollow tube 3 does not excessively occupy the space of the valve seat cavity 41, allowing sufficient space for liquid nitrogen within the valve seat cavity 41 without hindering its flow and distribution. This ensures that the valve seat cavity 41 can fully play its role in cryogenic environment simulation. This reduces ineffective space occupation, optimizes the effective utilization space of the valve seat cavity 41, reduces the amount of liquid nitrogen required to maintain the cryogenic environment, further improves the utilization rate of liquid nitrogen, and avoids the impact of excessively long hollow tube 3 on the stability of the cryogenic environment within the valve seat cavity 41 of the safety valve 4 under test and the accuracy of related test parameters.

[0039] Specifically, such as Figure 2 As shown, the top of the low-temperature test flange 1 is provided with several bolt fixing holes 13, which are connected and fixed to the safety valve 4 to be tested by bolts.

[0040] The low-temperature test flange 1 has bolt fixing holes 13 on its top, which are used to connect and fix it to the safety valve 4 under test via bolts. This bolted connection provides a detachable and stable mechanical connection between the low-temperature test flange 1 and the safety valve 4 under test, facilitating the replacement of different specifications of the safety valve 4 according to different testing requirements. This enhances the ease of operation of the device, adapts to the testing needs of different specifications of low-pressure safety valves, reduces the workload of operators during the installation and removal of the safety valve 4 under test, and ensures the stability of the connection during testing, preventing loose connections from affecting the accuracy of test results.

[0041] Furthermore, such as Figure 5As shown, the liquid nitrogen inlet channel 11 is provided with a vertical internal thread 15 at one end near the hollow tube 3, and the lower end of the hollow tube 3 is provided with an external thread. The internal thread 15 is threadedly connected to the lower end of the hollow tube 3.

[0042] The liquid nitrogen inlet channel 11 has an internal thread 15 near the hollow tube 3, and the lower end of the hollow tube 3 has an external thread. The two are connected by threads, which enables a detachable connection between the liquid nitrogen inlet channel 11 and the hollow tube 3, and effectively ensures sealing during the connection process to prevent liquid nitrogen leakage. This connection method facilitates the quick separation and connection of the liquid nitrogen inlet channel 11 and the hollow tube 3 during device assembly, maintenance, and component replacement, improving the assembly efficiency of the device. At the same time, it ensures the sealing of the liquid nitrogen transmission process, ensuring that liquid nitrogen can be stably and efficiently delivered to the hollow tube 3 and then enter the valve seat cavity 41, providing a stable low-temperature environment for testing.

[0043] Furthermore, such as Figure 5 As shown, an overflow channel 14 is provided in the middle of the top of the low-temperature pressure test flange 1. The hollow tube 3 passes vertically through the overflow channel 14. The diameter of the overflow channel 14 is larger than the outer diameter of the hollow tube 3. The upper end of the overflow channel 14 is connected to the inner cavity 41 of the valve seat, and the lower end of the overflow channel 14 is connected to the liquid nitrogen outlet channel 12.

[0044] An overflow channel 14 is opened in the middle of the top of the cryogenic test flange 1. A hollow tube 3 vertically passes through the overflow channel 14. The diameter of the overflow channel 14 is larger than the outer diameter of the hollow tube 3. The upper end of the overflow channel 14 is connected to the inner cavity 41 of the valve seat, and the lower end is connected to the liquid nitrogen outlet channel 12. When there is too much liquid nitrogen or the pressure is too high in the inner cavity 41 of the valve seat, liquid nitrogen can flow into the liquid nitrogen outlet channel 12 through the overflow channel 14, thereby regulating the amount and pressure of liquid nitrogen in the inner cavity 41 of the valve seat. This ensures the stability of the liquid nitrogen environment in the inner cavity 41 of the valve seat and avoids the test results of the safety valve 4 under test being affected by excessive liquid nitrogen or abnormal pressure. At the same time, together with the structure of the liquid nitrogen inlet channel 11 and the hollow tube 3, a complete liquid nitrogen circulation path is formed, which further improves the simulation effect of the device on the cryogenic environment and ensures the test accuracy.

[0045] Furthermore, such as Figure 3 As shown, a pressure gauge 6 is installed on the test connector 5, and a vent valve 61 is installed on the connecting pipe of the pressure gauge 6.

[0046] A pressure gauge 6 is installed on the test connector 5 to monitor the pressure inside the valve seat cavity 41 in real time. A vent valve 61 is installed on the pipeline connected to the pressure gauge 6. When the pressure is too high, some gas can be released through the vent valve 61 to regulate the pressure. By using the pressure monitoring and regulation device, precise control of the pressure inside the valve seat cavity 41 can be achieved. It can accurately adapt to low-pressure testing requirements, providing accurate pressure data for evaluating key indicators such as the set pressure of the safety valve 4 under test, ensuring that the pressure parameters are within a controllable range during the test, and guaranteeing test accuracy and safety. The test accuracy is comparable to that of large pressure vessels.

[0047] Furthermore, such as Figure 4 As shown, an exhaust pipe 7 is installed at the outer end of the test connector 5, a three-way pipe 8 is installed at the outer end of the exhaust pipe 7, a temperature measuring port 81 is provided at one end of the three-way pipe 8, and a gas mass flow meter 9 is connected to the upper interface of the three-way pipe 8.

[0048] The test connector 5 is sequentially connected to an exhaust pipe 7 and a three-way pipe 8. One end of the three-way pipe 8 has a temperature measuring port 81, and the upper end is connected to a gas mass flow meter 9. When the safety valve 4 under test is opened, the discharged gas flows through the exhaust pipe 7 and the three-way pipe 8. The temperature sensor connected to the temperature measuring port 81 measures the gas temperature, while the gas mass flow meter 9 measures the gas flow rate. This allows for the acquisition of key parameters of the gas discharged after the safety valve 4 is opened. This provides more crucial data for a comprehensive evaluation of the performance of the safety valve 4 under test. Combined with pressure data, it enables a more accurate assessment of the set pressure, sealing performance, and other indicators of the safety valve 4 under test, further improving testing accuracy and refining the performance evaluation system for the safety valve 4 under test.

[0049] Furthermore, an external temperature sensor is connected to the temperature measuring port 81 for gas temperature measurement.

[0050] An external temperature sensor is connected to temperature measuring port 81. Based on the thermistor characteristics of the temperature sensor, the temperature of the gas flowing through temperature measuring port 81 is sensed in real time, and the temperature signal is converted into an electrical signal for output, thus realizing the measurement of gas temperature. This provides temperature-related data support for the testing of safety valve 4 under test. When evaluating the performance of safety valve 4 under test in low-temperature environments, temperature is an important reference factor, which helps to more accurately determine the operating status of safety valve 4 under actual operating temperature conditions, ensuring the comprehensiveness and accuracy of test results.

[0051] Furthermore, a switch valve 91 is installed on the connecting pipe of the gas mass flow meter 9, and the gas mass flow meter 9 is used to measure the gas flow rate.

[0052] A switch valve 91 is installed on the connecting pipeline of the gas mass flow meter 9 to control the on / off state of the gas mass flow meter 9. When gas flow needs to be measured, the switch valve 91 is opened, and gas flows through the gas mass flow meter 9. Utilizing the sensing element inside the gas mass flow meter 9, the gas flow data is measured and output based on the effect of the gas flow on the sensing element. This achieves controllability of the gas flow measurement process, avoiding unnecessary losses to the gas mass flow meter 9 due to continuous gas flow when measurement is not needed. At the same time, it ensures accurate measurement of the gas flow after the safety valve 4 under test is opened during the test, providing accurate data for the performance evaluation of the safety valve 4 under test.

[0053] Furthermore, the test connector 5 is threadedly connected to the liquid nitrogen outlet channel 12, and the test connector 5 is threadedly connected to the exhaust pipe 7, with sealing tape installed at the connection.

[0054] The test connector 5 is threadedly connected to the liquid nitrogen outlet channel 12 and the exhaust pipe 7, and sealing tape is installed at the connection points. The tightness of the threaded connection and the sealing effect of the tape ensure the airtightness of the connection between the test connector 5 and the liquid nitrogen outlet channel 12 and the exhaust pipe 7, preventing gas or liquid nitrogen leakage. This ensures the airtightness of the entire testing system, maintains the stability of the low temperature and pressure testing environment within the valve seat cavity 41, and avoids changes in the testing environment due to leakage, which could affect the accuracy of the test results. It also ensures the safety of the testing process, preventing injury to operators from liquid nitrogen or high-pressure gas leaks.

[0055] The cryogenic and low-pressure safety valve testing device of this invention, based on the principle of direct contact with the cryogenic medium and real-time parameter monitoring, uses liquid nitrogen provided by a Dewar flask as a cryogenic source. It utilizes a closed-loop system to simulate the actual working environment of the safety valve 4 under test, enabling precise testing of its set pressure, sealing performance, and other indicators. Specifically, liquid nitrogen enters the liquid nitrogen inlet channel 11 through the Dewar flask interface 2 and is directly delivered to the valve seat cavity 41 of the safety valve 4 under test through the hollow tube 3, quickly establishing a cryogenic environment. Simultaneously, using components such as the pressure gauge 6, gas mass flow meter 9, and temperature measuring port 81 connected to the detection connector 5, the pressure, gas flow rate, and temperature of the valve seat cavity 41 are monitored in real time. Combined with the venting valve 61 and the switching valve 91, parameter adjustment is achieved, ultimately completing the performance evaluation of the low-pressure cryogenic safety valve.

[0056] Work process The safety valve 4 to be tested is sealed and connected to the cryogenic pressure test flange 1 through the bolt fixing hole 13, ensuring a tight fit at the connection. The hollow tube 3 is connected to the internal thread 15 of the liquid nitrogen inlet channel 11 through the external thread, so that its upper end extends into the inner cavity 41 of the valve seat without exceeding the height of the inner cavity. The test connector 5 is threaded to the liquid nitrogen outlet channel 12 and the exhaust pipe 7 respectively, and the connection is wrapped with sealing tape to ensure sealing. The end of the exhaust pipe 7 is connected to the tee pipe 8 in sequence, and a temperature sensor is installed at the temperature measuring port 81 of the tee pipe 8. The upper interface is connected to the gas mass flow meter 9 through the switch valve 91. Finally, the Dewar canister interface 2 is connected to the external liquid nitrogen Dewar canister to complete the assembly of the device.

[0057] Open the Dewar flask valve, and liquid nitrogen enters the liquid nitrogen inlet channel 11 through the Dewar flask interface 2, and is directly injected into the valve seat cavity 41 of the safety valve 4 under test through the hollow tube 3. The liquid nitrogen is in direct contact with the sealing surface of the valve seat cavity 41, rapidly reducing its temperature; when the liquid nitrogen in the valve seat cavity 41 reaches a certain amount or the pressure increases, the excess liquid nitrogen flows into the liquid nitrogen outlet channel 12 through the overflow channel 14, and is then discharged through the detection connector 5 and the exhaust pipe 7, ensuring the stability of the low temperature environment. This process lasts for 1-2 minutes until the temperature sensor shows that the temperature of the valve seat cavity 41 has reached the test requirements.

[0058] Close the vent valve 61 and the on / off valve 91, and slowly increase the output pressure of the Dewar flask. Monitor the pressure change in the valve seat cavity 41 in real time using pressure gauge 6. When the pressure reaches the nominal sealing pressure of the safety valve 4 under test, maintain the pressure for 30 seconds and observe whether the reading of pressure gauge 6 is stable: if the pressure does not drop significantly, the safety valve's sealing performance is qualified; if the pressure drops beyond the standard value, the sealing performance is deemed unqualified. If the pressure is too high, some gas can be released through the vent valve 61 to adjust the pressure to the target value.

[0059] Continue to slowly increase the pressure in the valve seat cavity 41. When the safety valve 4 under test opens, record the pressure value displayed on the pressure gauge 6, which is its set pressure. At the same time, open the switch valve 91. The gas discharged from the safety valve enters the gas mass flow meter 9 through the exhaust pipe 7 and the three-way pipe 8. Measure the gas flow rate per unit time. This data is used to evaluate the discharge performance of the safety valve. During this process, the temperature sensor at the temperature measuring port 81 simultaneously records the temperature of the discharged gas as an auxiliary parameter for performance evaluation in low-temperature environments.

[0060] After the test is completed, close the Dewar canister valve, open the vent valve 61 to release the residual pressure in the valve seat cavity 41, and when the pressure gauge 6 shows zero pressure, disassemble the safety valve 4 to be tested, clean the residual liquid nitrogen in the hollow tube 3, overflow channel 14 and other components, close all valves, and complete one test procedure.

[0061] Finally, it should be noted that the gas mass flow meter 9, temperature sensor, and other electronic components in this embodiment are all general standard parts or parts known to those skilled in the art. Their structure and principle can be learned by those skilled in the art through technical manuals or conventional experimental methods. In the idle part of this device, all the above-mentioned electrical components are connected by wires. The specific connection method should refer to the working order of each electrical component in the above working principle to complete the electrical connection. All of these are technologies known in the art.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-temperature, low-pressure safety valve testing device, comprising a low-temperature testing flange (1), characterized in that: The top of the low-temperature test flange (1) is detachably equipped with a safety valve (4) to be tested. A liquid nitrogen inlet channel (11) is provided on one side of the low-temperature test flange (1). A hollow tube (3) is vertically installed in the middle of the low-temperature test flange (1). One end of the liquid nitrogen inlet channel (11) is connected to the hollow tube (3). The other end of the liquid nitrogen inlet channel (11) is equipped with a Dewar canister interface (2). The upper end of the hollow tube (3) extends into the bottom valve seat cavity (41) of the safety valve (4) to be tested. A liquid nitrogen outlet channel (12) is provided on the other side of the low-temperature test flange (1). A test connector (5) is installed at one end of the liquid nitrogen outlet channel (12). The other end of the liquid nitrogen outlet channel (12) is connected to the valve seat cavity (41). An overflow channel (14) is provided in the middle of the top of the low-temperature pressure test flange (1). The hollow tube (3) passes vertically through the overflow channel (14). The diameter of the overflow channel (14) is larger than the outer diameter of the hollow tube (3). The upper end of the overflow channel (14) is connected to the inner cavity (41) of the valve seat, and the lower end of the overflow channel (14) is connected to the liquid nitrogen outlet channel (12).

2. The low-temperature and low-pressure safety valve testing device according to claim 1, characterized in that: The length of the upper part of the hollow tube (3) extending out of the low-temperature test flange (1) is less than the height of the valve seat cavity (41).

3. The low-temperature and low-pressure safety valve testing device according to claim 1, characterized in that: The top of the low-temperature test flange (1) is provided with several bolt fixing holes (13), and the bolt fixing holes (13) are connected and fixed to the safety valve (4) to be tested by bolts.

4. The low-temperature and low-pressure safety valve testing device according to claim 1, characterized in that: The liquid nitrogen inlet channel (11) is provided with a vertical internal thread (15) at one end near the hollow tube (3), and the lower end of the hollow tube (3) is provided with an external thread. The internal thread (15) is threadedly connected to the lower end of the hollow tube (3).

5. The low-temperature and low-pressure safety valve testing device according to claim 1, characterized in that: A pressure gauge (6) is installed on the test connector (5), and a vent valve (61) is installed on the connecting pipe of the pressure gauge (6).

6. The low-temperature and low-pressure safety valve testing device according to claim 5, characterized in that: An exhaust pipe (7) is installed at the outer end of the detection connector (5), and a three-way pipe (8) is installed at the outer end of the exhaust pipe (7). A temperature measuring port (81) is provided at one end of the three-way pipe (8), and a gas mass flow meter (9) is connected to the upper interface of the three-way pipe (8).

7. The low-temperature and low-pressure safety valve testing device according to claim 6, characterized in that: The temperature measuring port (81) is connected to an external temperature sensor for gas temperature measurement.

8. The low-temperature and low-pressure safety valve testing device according to claim 7, characterized in that: A switch valve (91) is installed on the connecting pipe of the gas mass flow meter (9), which is used to measure the gas flow rate.

9. The low-temperature and low-pressure safety valve testing device according to claim 1, characterized in that: The detection connector (5) is threadedly connected to the liquid nitrogen outlet channel (12), and the detection connector (5) is threadedly connected to the exhaust pipe (7), with sealing tape installed at the connection.

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