Leakage test method and test device for an internal system in an explosion-proof enclosure
By connecting the vacuum equipment and a high-pressure air source in the explosion-proof housing, the leakage performance of the built-in system is measured, and the problems of poor operability and insure of sealing performance in the prior art are solved, and the accuracy and reliability of the built-in system leakage test are achieved.
Patent Information
- Application Number
- CN202310523380.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-10
- Publication Date
- 2025-06-10
- Estimated Expiration
- 2043-05-10
AI Technical Summary
The built-in system leakage test method in the prior art is not very operable, the implementation process cannot be described in detail, and the sealing performance of the explosion-proof shell cannot be ensured, which affects the accuracy of the built-in system leakage test.
A leakage test method of the built-in system in the explosion-proof housing is adopted. By connecting the vacuum evacuation device to the explosion-proof housing, and connecting a high-pressure air source to the built-in system, filling helium to 1kPa, obtaining the initial pressure inside the explosion-proof housing, starting the vacuum evacuation device, and measuring the first time length. If the vacuum cannot be evacuated to 0.1Pa within this time length, it is determined that the built-in system leakage is unqualified.
This method improves the operability and accuracy of the built-in system leakage test, can accurately quantify and determine the leakage test results, and ensure the reliability of the built-in system.
Smart Images
Figure CN116625597B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of explosion-proof detection, and particularly relates to a leakage test method and test device for an internal system in an explosion-proof enclosure. Background Art
[0002] With the development and progress of social economy, more and more devices need to meet the requirements of miniaturization, integration, automation, and intelligence. The specific manifestation of such devices in explosion-proof products is the need to analyze and control process fluids on-site. Such a device is an explosion-proof enclosure with an internal release source (internal system). For explosion-proof enclosure products with an internal system, when conducting explosion-proof safety inspections on them, it is necessary to inspect the leakage performance of the internal system to verify the reliability of the internal system.
[0003] Although the current standard stipulates the method and qualified standard for the leakage test of the internal system, this method is only a basic requirement and does not describe the implementation process in detail, so its operability is not strong. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a leakage test method and test device for an internal system in an explosion-proof enclosure in view of the deficiencies of the prior art.
[0005] To solve the above technical problems, the technical solution adopted by the present invention is:
[0006] A leakage test method for an internal system in an explosion-proof enclosure includes:
[0007] S1. Connect a vacuum pumping device to the explosion-proof enclosure and connect a high-pressure gas source to the internal system;
[0008] S2. Start the high-pressure gas source to fill the internal system with helium gas to 1 kPa;
[0009] S3. Obtain the initial pressure inside the explosion-proof enclosure, start the vacuum pumping device to extract the air inside the explosion-proof enclosure, and at the same time obtain the first time period;
[0010] S4. If the absolute pressure inside the explosion-proof enclosure still does not reach 0.1 Pa after the first time period, it is determined that the leakage test of the internal system is unqualified;
[0011] S5. After the absolute pressure inside the explosion-proof enclosure reaches 0.1 Pa, the vacuum pumping device continues to extract for a second time period. If the absolute pressure inside the explosion-proof enclosure is not greater than 0.1 Pa within the second time period, it is determined that the leakage test of the internal system is qualified; otherwise, it is determined that the leakage test of the internal system is unqualified.
[0012] Further, the first time period T = 2.303×(V / S)×lg(P 0 / P2 ) × R, V = V 1 +V 2 , where V 1 is the volume of the flameproof cavity, V 2 is the internal volume of the pipeline conducted by the flameproof enclosure, S is the pumping speed of the vacuum pumping device, P 0 is the initial pressure of the flameproof enclosure, R is the adjustment coefficient, P 2 is the target pressure to be extracted, P 2 = 0.1 Pa.
[0013] Further, step S3 is as follows:
[0014] S31. Obtain the initial pressure inside the flameproof enclosure, start the vacuum pumping device to extract the air inside the flameproof enclosure, and simultaneously obtain the start time of the vacuum pumping device;
[0015] S32. Obtain the absolute pressure inside the flameproof enclosure at another moment;
[0016] S33. Obtain the first duration.
[0017] Further, the first duration T = (T 1 - T 0 ) × R × lg(P 0 / P 2 ) / lg(P 0 / P 1 ), where T 1 is the other moment, T 0 is the start time of the vacuum pumping device, P 0 is the initial pressure of the flameproof enclosure, P 1 is the absolute pressure inside the flameproof enclosure at the other moment T 1 , R is the adjustment coefficient, P 2 is the target pressure to be extracted, P 2 = 0.1 Pa.
[0018] Further, both the start time T 0 and the other moment T 1 are timestamps.
[0019] Further, the second duration is 1% of the first duration.
[0020] Further, the absolute pressure inside the flameproof enclosure is obtained by an absolute pressure gauge; the accuracy of the absolute pressure gauge is less than 0.1 Pa.
[0021] Further, the absolute pressure gauge is also used to transmit the pressure value to the host computer.
[0022] A leakage test device for a built-in system in an explosion-proof enclosure, comprising: a vacuum pumping device connected to the inside of the explosion-proof enclosure through a first pipeline, a high-pressure gas source connected to the inside of the built-in system through a second pipeline, a first pressure gauge for monitoring the absolute pressure inside the explosion-proof enclosure, and a second pressure gauge for monitoring the absolute pressure inside the built-in system;
[0023] The minimum pressure of the vacuum pumping device during pumping is not greater than 0.1 Pa, the maximum pressure of the high-pressure gas source during gas supply is not less than 1 kPa, and the accuracy of the first pressure gauge is less than 0.1 Pa.
[0024] Furthermore, it further includes a host computer, and the host computer is electrically connected to the first pressure gauge for obtaining the pressure value of the first pressure gauge.
[0025] The built-in system is a part of the equipment, and this part contains process fluids that may pass through the explosion-proof enclosure and cause release into the explosion-proof enclosure or the internal wiring system. In the current standard, the type test of the built-in system includes a leakage test, but the leakage test method specified in the standard is only a basic requirement, does not describe the implementation process in detail, and is not operable.
[0026] The current standard stipulates two leakage test methods. The first method requires filling the explosion-proof enclosure outside the built-in system with helium gas at the rated pressure, and at the same time evacuating the inside of the built-in system, so as to achieve the leakage gas flow from the outside to the inside of the built-in system, and determine whether the leakage test of the built-in system is qualified by monitoring the absolute pressure inside the built-in system. The second method requires filling the built-in system with helium gas at the rated pressure, and at the same time evacuating the explosion-proof enclosure outside the built-in system, so as to achieve the leakage gas flow from the inside to the outside of the built-in system, and determine whether the leakage test of the built-in system is qualified by monitoring the absolute pressure inside the explosion-proof enclosure.
[0027] Existing equipment has high requirements for the sealing performance of the built-in system. However, due to numerous interfaces on its external explosion-proof enclosure, it is impossible to ensure good sealing performance. Therefore, in the first method, if the high-pressure helium gas filled in the explosion-proof enclosure leaks, there is a risk of inert gas asphyxiation; while in the second method, the high-pressure helium gas is inside the built-in system, and helium gas is not easy to leak from the built-in system. Even if leakage occurs, it will still be blocked by the external explosion-proof enclosure, so the risk is lower. Secondly, the volume of helium gas filled in the first method is much larger than that filled in the second method, so the cost of helium gas used in the second method is smaller. Finally, the built-in system of the equipment is mostly connected to the manufacturer's own equipment, so standard interfaces may not be set. Due to the different interfaces of the built-in system and the single connection pipe orifice of the vacuum pumping device, it is difficult to operate when connecting the vacuum pumping device to the built-in system. Therefore, for the above reasons, based on the second method, this application proposes a leakage test method for the built-in system.
[0028] The second method requires evacuating the explosion-proof enclosure of the equipment under test. However, when the sealing performance of the explosion-proof enclosure cannot be guaranteed, if the absolute pressure of the explosion-proof enclosure does not meet the standard, it is impossible to determine whether it is caused by the leakage of the built-in system or the leakage of the explosion-proof enclosure. Therefore, it will interfere with the leakage test of the built-in system. In response to this situation, the present application can also use a sealed test tank as the explosion-proof enclosure of the equipment. During the test, the built-in system of the equipment under test is installed separately in the sealed test tank, or the entire equipment under test is placed in the sealed test tank. At the same time, the pipe orifice on the original explosion-proof enclosure of the equipment is opened to connect the inside and outside of the explosion-proof enclosure. The sealed test tank has good sealing performance and is widely used in the explosion-proof detection field, and can also be used in the leakage test of the built-in system. To ensure the integrity of the sealing performance of the sealed test tank, only two pipe orifices are provided on the tank body, one pipe orifice is used to connect the vacuum pumping device 3, and the other pipe orifice is used to connect the built-in system (the pipe orifice at the other end of the built-in system is sealed).
[0029] Since the leakage test of the built-in system is determined by observing whether the explosion-proof enclosure can maintain an absolute pressure of 0.1 Pa during the air extraction process of the vacuum pumping device, the air extraction speed of the vacuum pumping device cannot be too high. Otherwise, even if there is a leakage from the built-in system to the explosion-proof enclosure, if the air extraction speed is greater than the leakage speed, the explosion-proof enclosure will still maintain an absolute pressure of 0.1 Pa, resulting in a misjudgment of the leakage test result of the built-in system. However, when the air extraction speed of the vacuum pumping device is not high, it takes a long time to extract the air inside the explosion-proof enclosure of the equipment under test, especially when extracting the air inside the sealed test tank, and the air extraction time may even exceed 30 minutes. But the premise for determining the leakage test is that the explosion-proof enclosure needs to be evacuated to 0.1 Pa. During the evacuation process, if there is a leakage from the built-in system to the explosion-proof enclosure, the time required to evacuate the explosion-proof enclosure to 0.1 Pa will be greatly extended, which will greatly increase the consumption of the test time. Even in the case of serious leakage of the built-in system, the explosion-proof enclosure cannot be evacuated to 0.1 Pa.
[0030] Therefore, the present application sets an index of a first duration, representing the theoretical duration for evacuating the explosion-proof enclosure to 0.1 Pa, and uses this as the first determination criterion for the leakage performance of the built-in system. If the explosion-proof enclosure cannot be evacuated to 0.1 Pa within this first duration, it indicates that the built-in system has a leakage, and it can be directly determined that the leakage test of the built-in system is unqualified.
[0031] The first duration cannot be less than the theoretical duration for evacuating the flameproof enclosure to 0.1 Pa. That is, the first duration is determined by the theoretical extraction duration, which is related to the volume of the interior of the flameproof enclosure (flameproof cavity) and the pumping speed of the vacuum pumping equipment. Therefore, this application proposes a calculation method for the first duration, mainly based on the volume of the flameproof cavity and the pumping speed of the vacuum pumping equipment. However, considering that the volume of the flameproof cavity may not be accurately obtained, as well as the influence of other cavities in the pipeline and the inaccurate pumping speed of the vacuum pumping equipment, this application sets an adjustment coefficient in this calculation method so that the first duration can meet the actual needs.
[0032] Furthermore, this application also proposes another calculation method for the first duration. This method estimates the first duration by the change in the absolute pressure inside the flameproof enclosure within a certain period of time. The calculation process does not involve unquantifiable indicators such as the volume of the flameproof cavity and the pumping speed of the vacuum pumping equipment. Therefore, the calculated first duration will be more accurate. At the same time, an adjustment coefficient is still set so that the first duration can meet the actual needs.
[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0034] The built-in system leakage test method and leakage test device proposed in this application are highly operable, can accurately quantify and determine the leakage test results, and can test the reliability of the built-in system through the leakage test.
[0035] In the built-in system leakage test method proposed in this application, a first duration is also set. If the flameproof enclosure cannot be evacuated to 0.1 Pa within the first duration, it indicates that the built-in system has a leakage. Therefore, during the vacuum pumping stage, it can directly determine that the leakage test of the built-in system is unqualified. The first duration can be calculated using the volume of the flameproof cavity and the pumping speed of the vacuum pumping equipment, and an adjustment coefficient is set to correct the influence of unquantifiable indicators so that the first duration can meet the actual needs. The first duration can also be obtained by the change in the absolute pressure inside the flameproof enclosure within a certain period of time, thus excluding the influence of some unquantifiable indicators and making the calculated first duration more accurate.
[0036] This application also has a host computer. The host computer can obtain the absolute pressure inside the flameproof enclosure using the first pressure gauge. Therefore, the host computer can automatically calculate the first duration by monitoring the value of the first pressure gauge. At the same time, after the absolute pressure inside the flameproof enclosure reaches 0.1 Pa, the host computer can automatically determine whether the leakage test of the built-in system is qualified according to the reading of the first pressure gauge. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The following further describes the present invention in detail with reference to the accompanying drawings.
[0038] Figure 1: Schematic diagram of Embodiment 1 of the present invention;
[0039] Figure 2 : Schematic diagram of Embodiment 3 of the present invention;
[0040] Figure 3 : Flow chart of Embodiment 4 of the present invention;
[0041] Figure 4 : Flow chart of step S3 in Embodiment 5 of the present invention;
[0042] Wherein: 1 - flameproof enclosure, 2 - built-in system, 3 - vacuum pumping device, 4 - high-pressure gas source, 5 - first pressure gauge, 6 - second pressure gauge, 7 - first pipeline, 8 - second pipeline, 9 - first solenoid valve, 10 - second solenoid valve. Detailed implementation manners
[0043] To better understand the present invention, the content of the present invention will be further clearly described below in conjunction with embodiments and drawings. However, the protected content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.
[0044] Reference can be made to Figure 1 or Figure 2 , the built-in system 2 of the device to be tested is arranged inside its flameproof enclosure 1 and is communicated with the outside of the flameproof enclosure 1 through the inlet and outlet pipelines. This application is used to conduct a leakage test on the built-in system 2 to verify its reliability.
[0045] Embodiment 1: Refer to Figure 1 , the purpose of this embodiment is to provide a leakage test device for the built-in system in a flameproof enclosure. It includes: a vacuum pumping device 3 communicated with the inside of the flameproof enclosure 1 through the first pipeline 7, a high-pressure gas source 4 communicated with the inside of the built-in system 2 through the second pipeline 8, a first pressure gauge 5 for monitoring the absolute pressure inside the flameproof enclosure 1, and a second pressure gauge 6 for monitoring the absolute pressure inside the built-in system 2.
[0046] However, the sealing performance of the flameproof enclosure 1 of some devices to be tested cannot be guaranteed. During the test, gas leakage may occur in the flameproof enclosure 1, affecting the result of the leakage test of the built-in system. In view of this situation, this application sets a sealing test tank (such as an explosion test tank) to act as the flameproof enclosure 1. The built-in system 2 of the device to be tested is installed separately in the sealing test tank, or the whole device to be tested is placed in the sealing test tank, and at the same time, the opening on its flameproof enclosure is opened to ensure the internal communication between the flameproof enclosure and the sealing test tank. Therefore, Figure 1The explosion-proof enclosure 1 shown in the figure can be either the explosion-proof enclosure of the equipment to be tested itself or a separately provided sealed test tank. The sealed test tank must ensure good sealing performance. Therefore, only two pipe orifices can be provided on the tank body. One pipe orifice is used to connect the vacuum pumping device 3, and the other pipe orifice is used to connect the built-in system (the pipe orifice at the other end of the built-in system is sealed) to avoid affecting the sealing performance of the tank body due to the setting of too many pipe orifices.
[0047] To ensure the sealing performance, the explosion-proof enclosure 1 may not have any redundant pipe orifices. Therefore, after the first pipeline 7 is connected, there is no redundant pipe orifice on the explosion-proof enclosure 1 to install the first pressure gauge 5. Therefore, in this application, the first pressure gauge 5 is arranged on the first pipeline 7 or on the vacuum pumping device 3. Similarly, the second pressure gauge 6 is also arranged on the second pipeline 8 or on the high-pressure gas source 4. Both the first pipeline 7 and the second pipeline 8 are metal pipelines.
[0048] The minimum pressure for the vacuum pumping device 3 to pump air is not greater than 0.1 Pa, the maximum pressure for the high-pressure gas source 4 to supply gas is not less than 1 kPa, and the accuracy of the first pressure gauge 5 is less than 0.1 Pa. To meet the air pumping performance, the vacuum pumping device 3 can adopt a Roots diffusion vacuum unit; the high-pressure gas source 4 is used to supply helium gas, and a high-pressure helium gas cylinder can be selected.
[0049] The steps for conducting a leakage test on the built-in system 2 using this embodiment are as follows: Close the other pipe orifices of the built-in system 2, use the high-pressure gas source 4 to fill the built-in system 2 with helium gas. When the reading of the second pressure gauge 6 reaches 1 kPa, close the high-pressure gas source 4; then start the vacuum pumping device 3 to extract the air inside the explosion-proof enclosure 1. When the reading of the first pressure gauge 5 reaches 0.1 Pa, continuously obtain the reading of the first pressure gauge 5. If the reading of the first pressure gauge 5 does not exceed 0.1 Pa within a predetermined time period (such as 10 seconds), it is determined that the leakage test of the built-in system 2 is qualified. The predetermined time period can be determined according to parameters such as the size of the explosion-proof cavity of the equipment and the air pumping speed of the vacuum pumping device 3.
[0050] To facilitate reading the pressure values during the test, both the first pressure gauge 5 and the second pressure gauge 6 are digital pressure gauges.
[0051] Embodiment 2: The purpose of this embodiment is to provide a leakage test device for a built-in system in an explosion-proof enclosure. The following improvements are made to this embodiment based on Embodiment 1: It further includes a host computer.
[0052] Among them, the first pressure gauge 5 is a precision digital pressure gauge with an accuracy of 0.01 Pa and is electrically connected to the host computer, and can send the detected absolute pressure value of the explosion-proof enclosure 1 to the host computer; the host computer is used to record and analyze the absolute pressure of the explosion-proof enclosure 1 and is used to determine the leakage test result of the built-in system 2.
[0053] The host computer is also electrically connected to the vacuum pumping device 3 and can control the start or stop of the vacuum pumping device 3.
[0054] The steps of performing a leak test on the built-in system 2 using this embodiment are as follows: Close other pipe orifices of the built-in system 2, and use the high-pressure gas source 4 to fill helium into the built-in system 2. When the reading of the second pressure gauge 6 reaches 1 kPa, close the high-pressure gas source 4; then start the vacuum pumping device 3 to extract the air inside the explosion-proof enclosure 1. The host computer continuously obtains and records the reading of the first pressure gauge 5. After the reading of the first pressure gauge 5 reaches 0.1 Pa, continue to extract for a predetermined duration (such as 10 seconds) and then end the test; the host computer analyzes the recorded absolute pressure values. If all other data within the predetermined duration after the first data not greater than 0.1 Pa are not greater than 0.1 Pa, it is determined that the leak test of the built-in system 2 is qualified. The predetermined duration can be determined according to parameters such as the size of the explosion-proof cavity of the device and the air extraction speed of the vacuum pumping device 3.
[0055] Embodiment 3: Refer to Figure 2 , the purpose of this embodiment is to provide a leak test device for a built-in system in an explosion-proof enclosure. The following improvements are made to this embodiment based on Embodiment 2: A first solenoid valve 9 is further provided on the first pipeline 7, and a second solenoid valve 10 is further provided on the second pipeline 8. The first solenoid valve 9 is located between the first pressure gauge 5 and the vacuum pumping device 3, and the second solenoid valve 10 is located between the second pressure gauge 6 and the high-pressure gas source 4.
[0056] And both the first solenoid valve 9 and the second solenoid valve 10 are electrically connected to the host computer, enabling the host computer to control the on-off of the first pipeline 7 and the second pipeline 8. The second pressure gauge 6 is electrically connected to the host computer, enabling the host computer to obtain the absolute pressure of the built-in system 2.
[0057] The steps of performing a leak test on the built-in system 2 using this embodiment are as follows: Close other pipe orifices of the built-in system 2, and use the high-pressure gas source 4 to fill helium into the built-in system 2. When the host computer detects that the absolute pressure of the built-in system 2 reaches 1 kPa, use the second solenoid valve 10 to close the second pipeline 8; then start the vacuum pumping device 3 to extract the air inside the explosion-proof enclosure 1. The host computer continuously obtains and records the reading of the first pressure gauge 5. After the reading of the first pressure gauge 5 reaches 0.1 Pa, use the first solenoid valve 9 to close the first pipeline 7, and continue the test for a predetermined duration (such as 10 seconds) and then end the test; the host computer analyzes the recorded absolute pressure values. If the pressure value at the end of the test is less than the preset value, it is determined that the leak test of the built-in system 2 is qualified. The predetermined duration and the preset value can be determined according to parameters such as the size of the explosion-proof cavity of the device and the air extraction speed of the vacuum pumping device 3.
[0058] Example 4: The purpose of this example is to provide a leakage test method for the built-in system in an explosion-proof enclosure. The test method is implemented using the leakage test device described in Example 1. As Figure 3 shown, the test method includes:
[0059] Step S1, connect a vacuum pumping device 3 to the explosion-proof enclosure 1, and connect a high-pressure gas source 4 to the built-in system 2.
[0060] As Figure 2 shown, the vacuum pumping device 3 is connected to the pipe opening on the explosion-proof enclosure 1 using a first pipeline 7, enabling the vacuum pumping device 3 to extract the air inside the explosion-proof enclosure 1. The high-pressure gas source 4 is connected to the pipe opening at one end of the built-in system 2 using a second pipeline 8, and the pipe opening at the other end of the built-in system 2 is closed.
[0061] Meanwhile, a first pressure gauge 5 capable of detecting the absolute pressure inside the explosion-proof enclosure 1 is provided on the vacuum pumping device 3 or the first pipeline 7; a second pressure gauge 6 capable of detecting the absolute pressure inside the built-in system 2 is provided on the high-pressure gas source 4 or the second pipeline 8.
[0062] The minimum pressure for the vacuum pumping device 3 to pump air is not greater than 0.1 Pa, the maximum pressure for the high-pressure gas source 4 to supply gas is not less than 1 kPa, and the accuracy of the first pressure gauge 5 is less than 0.1 Pa. To meet the air extraction performance, the vacuum pumping device 3 can adopt a Roots diffusion vacuum unit; the high-pressure gas source 4 is used to supply helium gas and a high-pressure helium gas cylinder can be selected.
[0063] Step S2, start the high-pressure gas source 4 to fill the built-in system 2 with helium gas up to 1 kPa.
[0064] Use the high-pressure gas source 4 to fill the built-in system 2 with helium gas. When the reading of the second pressure gauge 6 reaches 1 kPa, close the high-pressure gas source 4 to stop the gas filling.
[0065] Step S3, obtain the initial pressure inside the explosion-proof enclosure 1, start the vacuum pumping device 3 to extract the air inside the explosion-proof enclosure 1, and simultaneously obtain a first duration T.
[0066] Use the first pressure gauge 5 to obtain the initial pressure P 0 inside the explosion-proof enclosure 1, obtain the first duration T, T = 2.303×(V / S)×lg(P 0 / P 2 )×R, V = V 1 +V 2 . Among them, the first duration T is the maximum duration for evacuating the explosion-proof enclosure 1 during the test, with the unit of S; V is the volume of the cavity where the air is to be extracted, V 1 is the volume of the internal cavity of the explosion-proof enclosure 1 (excluding the built-in system 2, that is, the volume of the explosion-proof cavity), V 2The volume of the internal cavity of the pipeline (such as the first pipeline 7) conducted by the flameproof enclosure 1, V, V 1 and V 2 are all in liters; S is the rated pumping speed of the vacuum pumping device 3, in liters per second; P 0 is the initial pressure of the flameproof enclosure 1, in pascals; P 2 is the pressure reached after extraction, in pascals; R is an adjustment coefficient. In this application, the absolute pressure value of the flameproof enclosure 1 during the leakage test of the built-in system 2 should reach 0.1 Pa, that is, P 2 = 0.1 Pa. Considering that the volume of the flameproof cavity may not be accurately obtained and the influence of other cavities in the pipeline, an adjustment coefficient R is set to eliminate the above influence, and R can take the value of 1.25; of course, in actual applications, the value of R can be determined according to the situation of the vacuum pumping device 3, the device to be tested, etc.
[0067] The first duration T can be calculated before starting the vacuum pumping device 3.
[0068] Step S4, if the absolute pressure inside the flameproof enclosure 1 still does not reach 0.1 Pa after the first duration T, it is determined that the leakage test of the built-in system 2 is unqualified.
[0069] When the built-in system 2 is in good seal (qualified leakage performance), the flameproof enclosure 1 can extract air to 0.1 Pa within a time period less than the first duration T. If after exceeding the first duration T, the reading of the first pressure gauge 5 is still greater than 0.1 Pa, it means that the built-in system 2 is leaking gas into the flameproof enclosure 1 (it has been determined that the seal performance of the flameproof enclosure 1 is good), so it can be directly determined that the leakage test of the built-in system 2 is unqualified.
[0070] Step S5, after the absolute pressure inside the flameproof enclosure 1 reaches 0.1 Pa, the vacuum pumping device 3 continues to pump for a second duration. If the absolute pressure inside the flameproof enclosure 1 is not greater than 0.1 Pa during the second duration, it is determined that the leakage test of the built-in system 2 is qualified.
[0071] After the absolute pressure inside the flameproof enclosure 1 reaches 0.1 Pa, continuously obtain the reading of the first pressure gauge 5, and at the same time, the vacuum pumping device 3 continues to extract the air inside the flameproof enclosure 1 for a second duration. If during the second duration, the reading of the first pressure gauge 5 is not greater than 0.1 Pa, it is determined that the leakage test of the built-in system 2 is qualified. If within the second duration, the reading of the first pressure gauge 5 is greater than 0.1 Pa, it is determined that the leakage test of the built-in system 2 is unqualified.
[0072] The second duration can be 1% of the first duration T, or it can be determined according to the situation of the device to be tested and the parameters of the vacuum pumping device 3.
[0073] After the test, slowly release the high-pressure gas inside the built-in system 2 and the vacuum inside the flameproof enclosure 1.
[0074] Example 5: The purpose of this example is to provide a leakage test method for the built-in system in a flameproof enclosure, and this test method is implemented using the leakage test device described in Example 2. The following improvements are made based on Example 4:
[0075] The reading of the first pressure gauge 5 (i.e., the absolute pressure value inside the flameproof enclosure 1) can also be obtained by the host computer, and the start and stop of the vacuum pumping device 3 can be controlled by the host computer.
[0076] As Figure 4 shown, the specific steps of this example in step S3 are as follows:
[0077] S31. Obtain the initial pressure inside the flameproof enclosure 1 as P 0 , start the vacuum pumping device 3 to extract the air inside the flameproof enclosure 1, and at the same time obtain the start time T 0 of the vacuum pumping device 3.
[0078] The host computer uses the first pressure gauge 5 to obtain the initial pressure inside the current flameproof enclosure 1 as P 0 , then starts the vacuum pumping device 3 to start extracting the air inside the flameproof enclosure 1, and obtains the current time (the start extraction time of the vacuum pumping device 3) as T 0 . T 0 can be a timestamp.
[0079] S32. Obtain the absolute pressure P 1 inside the flameproof enclosure 1 at another time T 1 .
[0080] When the vacuum pumping device 3 works for a period of time, the host computer obtains the current time as T 1 , T 1 can be a timestamp; and uses the first pressure gauge 5 to obtain the absolute pressure inside the current flameproof enclosure 1 as P 1 . Another time T 1 can be selected in the first half of the vacuum pumping process, such as T 1 = T 0 + 300S.
[0081] S33. Obtain the first duration T.
[0082] (T 1 - T 0 ) = 2.303×(V / S)×lg(P 0 / P 1), where V is the volume of the cavity from which air is to be extracted (including the volume of the explosion-proof cavity and the volume of the pipeline), and S is the rated air extraction speed of the vacuum extraction device 3. However, in actual applications, the volume V cannot be accurately obtained, and the air extraction speed S is also related to the operating conditions of the vacuum extraction device 3. Therefore, the accurate values of V and S are not obtained in this step.
[0083] Converting the above formula gives V / S = (T 1 -T 0 ) / (lg(P 0 / P 1 ) × 2.303). Subsequently, combining with the calculation formula of the first duration T in Embodiment 4, T = 2.303×(V / S)×lg(P 0 / P 2 ), we can obtain T = (T 1 -T 0 ) × R × lg(P 0 / P 2 ) / lg(P 0 / P 1 ). Since the problem of inaccurate cavity volume is excluded in this step, the adjustment coefficient R can only take a value slightly larger than 1, such as 1.1.
[0084] When step S5 of this embodiment is executed, the host computer can automatically determine whether the built-in system 2 passes the leakage test according to the reading of the first pressure gauge 5. Specifically, the host computer analyzes the recorded absolute pressure values. If all other data within the second duration after the first data not greater than 0.1 Pa are also not greater than 0.1 Pa, it is determined that the leakage test of the built-in system 2 is qualified.
[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Any other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.
Claims
1. A leakage test method for a built-in system in an explosion-proof enclosure, characterized in that: It includes: S1. Connect a vacuum pumping device to the explosion-proof enclosure and connect a high-pressure gas source to the built-in system; S2. Start the high-pressure gas source to fill the built-in system with helium until it reaches 1 kPa; S3. Obtain the initial pressure inside the explosion-proof enclosure, start the vacuum pumping device to extract the air inside the explosion-proof enclosure, and at the same time obtain the first duration; S4. If the absolute pressure inside the explosion-proof enclosure still does not reach 0.1 Pa after the first duration, it is determined that the leakage test of the built-in system is unqualified; S5. After the absolute pressure inside the explosion-proof enclosure reaches 0.1 Pa, the vacuum pumping device continues to extract for a second duration. If the absolute pressure inside the explosion-proof enclosure is not greater than 0.1 Pa within the second duration, it is determined that the leakage test of the built-in system is qualified; otherwise, it is determined that the leakage test of the built-in system is unqualified; where The first time duration T = 2.303×(V / S)×lg(P 0 / P 2 )×R, V = V 1 +V 2 , where V 1 is the volume of the flameproof cavity, V 2 is the internal volume of the pipeline conducted by the flameproof enclosure, S is the pumping speed of the vacuum pumping equipment, P 0 is the initial pressure of the flameproof enclosure, R is the adjustment coefficient, P 2 is the target pressure to be extracted, P 2 = 0.1 Pa.
2. The leakage test method for a built-in system in an explosion-proof enclosure according to claim 1, characterized in that: Step S3 is: S31. Obtain the initial pressure inside the explosion-proof enclosure, start the vacuum pumping device to extract the air inside the explosion-proof enclosure, and at the same time obtain the starting moment of the vacuum pumping device; S32. Obtain the absolute pressure inside the explosion-proof enclosure at another moment; S33. Obtain the first duration.
3. The leakage test method for a built-in system in an explosion-proof enclosure according to claim 2, characterized in that: The first duration T = (T 1 - T 0 ) × R × lg(P 0 / P 2 ) / lg(P 0 / T 1 ), where T 1 is the other moment, T 0 is the starting moment of the vacuum pumping device, P 0 is the initial pressure of the flameproof enclosure, P 1 is the absolute pressure inside the flameproof enclosure at the other moment T 1 , R is the adjustment coefficient, P 2 is the target pressure to be extracted, P 2 = 0.1 Pa.
4. The leakage test method for a built-in system in an explosion-proof enclosure according to claim 3, characterized in that: The start time T 0 and the other time T 1 are both timestamps.
5. The leakage test method for a built-in system in an explosion-proof enclosure according to claim 1, characterized in that: The second duration is 1% of the first duration.
6. The leakage test method for a built-in system in an explosion-proof enclosure according to claim 1, characterized in that: The absolute pressure inside the explosion-proof enclosure is obtained by an absolute pressure gauge; the accuracy of the absolute pressure gauge is less than 0.1 Pa.
7. The leakage test method for a built-in system in an explosion-proof enclosure according to claim 6, characterized in that: The absolute pressure gauge is also used to transmit the pressure value to the upper computer.
Citation Information
Patent Citations
Method and device for leak test
JP2001033343A