A test method for electrostatic sensitivity of liquid materials based on surface discharge

Abstract

The invention discloses a liquid material electrostatic sensitivity test method based on surface discharge in the field of safety technology of the combustion and explosive articles industry, comprising the following steps: step 1: designing a liquid material electrostatic sensitivity test device for controlling electrostatic discharge; step 2: designing and manufacturing a sample loading module for liquid samples; step 3: installing and arranging the liquid material electrostatic sensitivity test device and the sample loading module; step 4: determining group test setting parameters according to the test device; step 5: setting single test setting parameters; step 6: loading the liquid material sample into the sample loading module; step 7: remotely controlling the electrostatic discharge of the test device; step 8: repeating steps 5 to 7 until the number of tests meets the requirement; step 9: calculating the electrostatic sensitivity distribution of the liquid material to be tested according to the set charging energy and response situation of each test. The invention has a high degree of safety and standardizes the electrostatic sensitivity test method of the liquid material through a specific operation process.

Description

Technical Field

[0001] The present invention relates to the technical field of safety of the burning explosives industry, and particularly to an electrostatic sensitivity test method for liquid burning explosives based on surface discharge. Background Art

[0002] Electrostatic sensitivity is a sensitivity index that characterizes the combustion and explosion characteristics of combustible explosives. It is an important basic data for analyzing the ignition reliability of industrial explosives and an important basis for evaluating the electrostatic safety risks of combustible explosives. The electrostatic sensitivity test requires a series of electrostatic spark discharge ignition tests to be carried out in sequence based on mathematical statistics methods, and finally the ignition probability of the test material under different electrostatic stimulation amounts is calculated according to the principles of mathematical statistics. Among them, the critical electrostatic stimulation amount corresponding to the maximum ignition probability can represent the electrostatic initiation reliability threshold, which is the basic data for evaluating the reliability of electric ignition and initiation of explosives such as industrial explosives; and the critical electrostatic stimulation amount corresponding to the minimum ignition probability can represent the electrostatic safety threshold, which is an important basis for evaluating the electrostatic safety risks of combustible explosives during production, transportation, use, and destruction.

[0003] The electrostatic sensitivity test refers to the relationship between the applied electrostatic stimulus and the sample response obtained through testing, which is a very complex issue. Existing studies have shown that it is impossible to obtain the minimum electrostatic ignition stimulus of a single sample through experiments. The reason is that the electrostatic spark discharge ignition test is an extremely special destructive test. For a specific sample, only one test can be carried out to determine the electrostatic stimulus, and only the response (ignition) or non-response (non-ignition) result can be observed, but repeated tests cannot be carried out [Yuan Junming, Liu Yucun. Research on NeyerD-optimized new sensitivity test method. Initiators, 2005, (2): 25-27], [Yuan Junming. Research on NeyerD-optimized sensitivity test method and its application: [Dissertation]. Taiyuan: North University of China, 2005], [Wang Chongde. Improvement of Langley method algorithm and comparison with traditional lifting method: [Dissertation]. Shanghai: East China Normal University, 2009], [Zhang Runqi, Wang Genglu. Data analysis method of OSTR method for sensitivity test. Journal of Beijing Institute of Technology, 1993, 13 (2): 286-290]. Therefore, it is impossible to measure the relationship between the response of a single sample and the amount of electrostatic stimulation through experiments. Instead, we can only conduct electrostatic spark discharge ignition tests on a series of similar industrial explosive samples to finally obtain the response probability distribution of the sample under different electrostatic stimulation amounts, that is, its electrostatic sensitivity.

[0004] Previous researchers have analyzed and optimized the mathematical statistics method for electrostatic sensitivity tests and found that the "Langley-Optimized D" method can be used to conduct electrostatic sensitivity tests, which can obtain relatively accurate minimum and maximum response probabilities corresponding to critical electrostatic stimulation quantities, which can be used to evaluate the electric ignition reliability and electrostatic safety risks of combustible and explosive materials, respectively [Sun Mingze, Wang Yanping, Luo Taiming, et al. Analysis and optimization of mathematical statistics methods for electrostatic sensitivity tests of explosives and propellants [J]. Journal of Explosives and Propellants, 2023, 46(3):10.]. These research conclusions are applicable to all sensitivity tests, such as electrostatic sensitivity tests and friction sensitivity tests, but do not provide specific test device design and test method guidance for electrostatic sensitivity tests.

[0005] The current domestic standards for electrostatic sensitivity testing of combustible explosives include: National Military Standard for Explosives Testing (GJB772A-1997), National Military Standard for Safety Test Methods for Booster Combustions (GJB2178-2005), National Military Standard for Sensitivity and Stability Test Methods for Pyrotechnics (GJB5383-2005), National Military Standard for Test Methods for Initiating Pyrotechnics (GJB5309-2004), National Military Standard for Safety Test Methods for Insensitive Explosives and Electrostatic Sensitivity (GJB8142-2013), and National Military Standard for Test Methods for Initiating Pyrotechnic Agents (GJB5891-2006). These test methods are specific to powders and solid samples and do not specify how to conduct electrostatic sensitivity testing on liquid materials.

[0006] In terms of the design of electrostatic sensitivity test equipment, Sun Liqing and others from the Xi'an Aerospace Propulsion Technology Research Institute proposed a solid motor electrostatic safety test device and method in 2016 [Sun Liqing, Liu Kai, Yuan Jun, et al. A solid motor electrostatic safety test device and method [P]. Shaanxi: CN201610489008.8, 2016-11-16.], which uses the electrical energy stored in the capacitor to oscillate and discharge the motor, thereby testing the electrostatic sensitivity of the solid motor; Rao Guoning from Nanjing University of Science and Technology et al. proposed a test device for the electrostatic sensitivity of the human body to burning explosives in 2019 [Rao Guoning, Ren Jiafan, Feng Bo, et al. A test device for the electrostatic sensitivity of the human body to burning explosives [P]. Jiangsu Province: CN201911088777.7, 2020-02-25.], which can simulate the static generation and release mode of the human body and measure the electrostatic sensitivity that is closer to the electrostatic discharge of the human body; Wu Guilin et al. of the Sichuan Aerospace Metrology and Testing Institute proposed an electrostatic sensitivity spark discharge test device in 2022, which can simulate the static generation and release mode of the human body and measure the electrostatic sensitivity that is closer to the electrostatic discharge of the human body. The precise adjustment of the discharge gap was realized [Wu Guilin, Yang Feng, Zhao Dan. An electrostatic sensitivity spark discharge test device [P]. Sichuan Province: CN202223392087.0, 2023-10-27.]; Ke Changzheng and others from Dongguan Kexiang Testing Equipment Co., Ltd. proposed an aerosol electrostatic sensitivity experimental device in 2023 [Ke Changzheng, Zheng Zhuangzhuang, Huang Cheng, et al. Aerosol electrostatic sensitivity experimental device [P]. Guangdong Province: CN202323261613.4, 2024-07-23 .], which can perform electrostatic sensitivity tests on gas samples such as aerosols; in 2023, Sun Mingze and others from the China Ordnance Industry Explosives Engineering and Safety Technology Research Institute proposed a lower electrode for a temperature-coupled powder electrostatic discharge sensitivity test system [Sun Mingze, Jin Changbin, Sun Jing. A lower electrode for a temperature-coupled powder electrostatic discharge sensitivity test system [P]. Beijing: CN202321557705.4, 2023-12-08.], which can perform electrostatic sensitivity tests on powder samples under temperature-coupled conditions. The above electrostatic sensitivity test devices are only designed for solid, powder, and gas (aerosol) samples. Currently, there is a lack of devices that can perform electrostatic sensitivity tests on liquid material samples.

[0007] The electrostatic sensitivity test method and test device design mentioned above are not suitable for liquid samples, cannot program-control test parameters such as charging capacitor voltage and sample temperature, and cannot remotely control electrostatic discharge to achieve human-machine isolation during the test process.

[0008] (1) Not suitable for liquid samples

[0009] The aforementioned electrostatic sensitivity test devices are designed only for solid, powder, and gas (aerosol) samples. Currently, there is a lack of devices and methods capable of conducting electrostatic sensitivity tests on liquid material samples. This is primarily due to the electrostatic spark discharge model used in existing electrostatic sensitivity tests, which is based on the theory of gas breakdown discharge. A large potential difference is applied across a small gap. When the static electric field strength in the air exceeds the air breakdown field (typically 3kV / mm), the air can be broken down at the gap to form a plasma discharge channel, achieving electrostatic spark discharge. For powder samples, due to their low bulk density, there are ample air gaps between the powder particles, and electrostatic spark discharge still occurs through these gaps. The same process occurs with aerosol samples, where the proportion of liquid particles in the air is relatively low, and electrostatic spark discharge occurs through the breakdown of air gaps. For solid materials such as solid propellant rockets, which are typically compressed from powders and have internal pores, localized material polarization breakdown under high electrostatic pressure creates air pathways, enabling electrostatic spark discharge. However, liquid materials generally fill the entire space without leaving any air gaps. At the same time, due to the internal fluid properties of the liquid material itself, it is not easy to locally break down to form an air path during the polarization process, and it is not easy to break down the liquid at both ends of the liquid material to generate electrostatic spark discharge.

[0010] (2) Unable to program and adjust test parameters such as charging capacitor voltage and sample temperature

[0011] Existing electrostatic sensitivity test equipment primarily features fixed charging circuit designs, meaning the charging capacitor and voltage are fixed and cannot be adjusted. The "Lower Electrode of a Temperature-Coupled Powder Electrostatic Discharge Sensitivity Test System" features a lower electrode structure that can adjust the sample test temperature, while the "Electrostatic Sensitivity Spark Discharge Test Device" incorporates a mechanism that can precisely adjust the discharge electrode gap. However, neither system implements host computer software control, requiring manual adjustment or individual device button adjustments. Consequently, programmable adjustment of test parameters such as the charging capacitor voltage and sample temperature is impossible, making the test process cumbersome and inefficient.

[0012] (3) It is impossible to achieve human-machine isolation during electrostatic discharge

[0013] The current sample response determination methods specified in test methods such as GJB772A-1997 and GJB2178-2005 all rely on observation. This requires manual observation for explosion flashes and listening for explosion sounds during the test, as well as post-test air temperature and sample identification. This fails to effectively isolate humans from the machine during the electrostatic discharge process. Existing test device designs, such as the "Electrostatic Safety Test Device and Method for Solid Propellant Rocket Rockets," also lack a clear definition of the human-machine isolation method and implementation structure. This may require close proximity between personnel and the user during electrostatic discharge, resulting in a low level of intrinsic safety in the test device design.

[0014] The present invention can provide a liquid material electrostatic sensitivity test method based on surface discharge, which can solve the above-mentioned problems and carry out electrostatic sensitivity tests on liquid materials. During the test process, parameters such as the charging capacitor voltage and temperature can be programmably adjusted, and electrostatic discharge can be remotely controlled to achieve human-machine isolation during the electrostatic discharge process, providing a more standardized and normalized method for obtaining electrostatic sensitivity data of liquid combustion and explosive items. Summary of the Invention

[0015] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and in the abstract and title of the present invention to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0016] The purpose of the present invention is to address the technical problems existing in the background technology. The present invention proposes a liquid material electrostatic sensitivity test method based on surface discharge. The present invention can solve the current problem of lack of devices and methods for conducting electrostatic sensitivity tests on liquid material samples.

[0017] The present invention proposes a method for testing the electrostatic sensitivity of liquid materials based on surface discharge, comprising the following steps:

[0018] Step 1: Design and manufacture a liquid material electrostatic sensitivity test device that can remotely adjust the charging capacitance and voltage and control electrostatic discharge. The device can be divided into three parts: remote control system, charging and discharging chamber, and experimental chamber.

[0019] Step 2: Design and manufacture a sample loading module for liquid samples to achieve an uneven electric field distribution at the liquid-air interface;

[0020] Step 3: Install and lay out the liquid material electrostatic sensitivity test device and the sample loading module, and ensure that the experimental cabin in front of the sample loading module is transparent and unobstructed. Place a high-frame rate camera in front of the sample loading module, and debug the entire test system.

[0021] Step 4: Determine the maximum charging capacitance, maximum charging voltage, minimum charging capacitance, and minimum charging voltage based on the test device, calculate the corresponding capacitance energy storage settings as the upper and lower limits of the test, and determine the test number, test temperature, electrode gap and other test setting parameters based on the test requirements;

[0022] Step 5: Based on the Langley-Optimized D method and the test data, calculate and set the single test parameters such as electrostatic charging capacitance and voltage for this test;

[0023] Step 6: Except for the first test, the remaining sample in the sample loading tank needs to be cleaned. Use a pipette or other pipetting mechanism to add the liquid material sample to the sample loading tank in the loading module, ensuring that the liquid level is flush with or slightly lower than the edge of the sample loading tank. Close the safety door of the experimental cabin and evacuate personnel to a safe location to achieve human-machine isolation;

[0024] Step 7: Run the high frame rate camera and set the parameters to remotely control the recording. Run the software on the host control computer to remotely control the electrostatic discharge of the test device. Use the video data recorded by the high frame rate camera to determine whether the sample responds.

[0025] Step 8: Repeat steps 5 to 7 until the number of tests meets the requirement;

[0026] Step 9: Based on the "maximum likelihood method", the electrostatic sensitivity distribution of the liquid material to be tested is calculated according to the set charging energy and response conditions of each test. Assuming that its electrostatic sensitivity distribution is a log-normal distribution, the calculation method is to optimize the mean μ and standard deviation σ to maximize the probability P of the pre-test results, and use the Newton method to iteratively solve its maximum point.

[0027] Preferably, in step 1, the remote control system includes a host computer, deploys test control software, and remotely controls the programmable high-voltage source, charging capacitor selection circuit, discharge main switch, electrode drive device, sample temperature control module and other mechanisms through optical fiber, network cable, etc., and performs operations in sequence according to program requirements to complete the liquid electrostatic sensitivity test.

[0028] Preferably, in step 1, the charging and discharging chamber includes four modules or parts: a programmable high-voltage source, a discharge circuit, a charging capacitor selection circuit, and a discharge main switch.

[0029] Preferably, in step 1, the experimental chamber part includes five modules or parts, namely, an electrode driving device, a discharge gap, a sample temperature control module, a sample loading slot and a heating device, and a temperature measuring device. The discharge gap, the sample loading slot and the heating device constitute a loading module. The spark discharge generated by the discharge circuit is loaded into the discharge gap to stimulate the sample in the sample loading slot, which may cause it to respond or not respond. The electrode driving device adjusts the position of the upper electrode to adjust the size of the discharge gap. The temperature measuring device feeds back the temperature of the sample loading slot to the sample temperature control module, and adjusts the heating device on the sample loading slot according to the set test temperature to control the sample temperature.

[0030] Preferably, the charging capacitor selection circuit is composed of a high-voltage conversion switch and a discharge resistor, the main discharge switch is a high-voltage conversion switch, connected to the discharge resistor, and finally connected to the upper electrode of the experimental cabin;

[0031] High voltage transfer switches are all controlled by remote control systems;

[0032] A charging resistor is connected in series between the programmable high voltage source and the main switch.

[0033] Preferably, in step 2, the sample loading module includes the discharge gap in the experimental chamber in step 1, the sample loading slot and the heating device part. The sample loading module is specifically composed of an upper electrode, a sample loading slot, a lower electrode, a semiconductor heating plate, a fixing thread and a grounding wire. During the electrostatic discharge process, the high-voltage switch controls the tip of the upper electrode to have a higher voltage, and the ground potential of the lower electrode is maintained at 0V. The liquid sample loading slot is filled with the liquid material to be tested, and a large potential and uneven electric field distribution are generated at the liquid-air interface, thereby realizing surface discharge at the liquid-gas interface.

[0034] Preferably, the upper electrode is made of stainless steel and has a pointed tip, and the upper portion is connected to the driving electrode via a polytetrafluoroethylene column.

[0035] Preferably, the sample loading groove is made of copper as the base material and the surface is silver-plated. The sample loading groove has a diameter of 8 mm, a depth of 1.2 mm, and a top distance from the semiconductor heating plate of 7 mm.

[0036] Preferably, the specific calculation steps of the "maximum likelihood method" in step 9 are as follows: Step 9.1: Record the charging energy E of all k trials Ci , and calculate the corresponding electrostatic stimulation amount x i =log(E Ci ), record the response v corresponding to all experiments i ;

[0037] Step 9.2: Determine the allowable error ε for parameter estimation and begin iteratively solving the maximum probability point of the test results based on the "Newton method";

[0038] Step 9.3: Find the corresponding v i =1 is denoted as x 1L , find the corresponding v i =0 is recorded as x 0U , x 1L and x 0U The number of stimulus amounts between m , and thus determine the initial value of the iterative calculation:

[0039]

[0040] Where: μ (0) Iterative initial value of the electrostatic sensitivity mean value;

[0041] σ (0) Iterative initial value of electrostatic sensitivity standard deviation;

[0042] k total number of trials;

[0043] x1L Minimum response stimulus amount;

[0044] x 0U Maximum non-response stimulus amount;

[0045] n m The number of stimulus amounts in the mixed interval;

[0046] Step 9.4: Calculate the following intermediate variables in sequence:

[0047]

[0048] Where: t is the number of iteration steps;

[0049] iDifferent test numbers;

[0050] u normal distribution coordination number;

[0051] p electrostatic sensitivity response probability;

[0052] Other parameters are used to calculate intermediate variables;

[0053] Step 9.5: Solve the two-variable equation system to obtain the change in the distribution parameters:

[0054]

[0055] Where: Δμ (t) Iterative increase of the mean value of sensitivity distribution;

[0056] Δσ (t) Iterative increase in the standard deviation of sensitivity distribution;

[0057] Step 9.6: Determine and suppress excessive changes: Ensure |Δμ (t) |<σ (t-1) And σ (t-1) / 2<Δσ (t) <2Δσ (t-1) If it is not satisfied, the change must be limited to this range;

[0058] Step 9.7: Add the mean and standard deviation of the electrostatic sensitivity distribution to the change to complete one iteration;

[0059] Step 9.8: Determine whether the sum of the absolute values of the two parameter changes is less than the allowable error ε. If not, repeat steps 9.4 to 9.7.

[0060] Step 9.9: Output the mean μ and standard deviation σ, and calculate the electrostatic discharge energy corresponding to different response probabilities.

[0061] In summary, the present invention has at least one of the following beneficial effects:

[0062] The electrostatic sensitivity test method of the present invention can be applied to liquid material samples. During the test process, test parameters such as charging capacitance, voltage, sample temperature, and electrode gap can be adjusted by a host computer program control. The electrostatic discharge process achieves human-machine isolation. The present invention has a high degree of safety and standardizes the electrostatic sensitivity test method of liquid materials through a specific operating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0064] Figure 1 is a flow chart of the test method of the present invention;

[0065] Figure 2 It is a system diagram of the test device of the present invention;

[0066] Figure 3 This is a schematic structural diagram of the test sample loading module of the present invention;

[0067] Figure 4 This is a flow chart of fitting electrostatic sensitivity distribution based on the "maximum likelihood method" of the present invention;

[0068] Figure 5 Schematic diagram of electrostatic spark discharge achieved by surface discharge at the liquid-air interface of the present invention;

[0069] Figure 6 This is a diagram showing the electrode dimensions of the sample loading module of the liquid electrostatic sensitivity test device of the present invention;

[0070] Figure 7 This is a layout diagram of the liquid electrostatic sensitivity test system of the present invention. DETAILED DESCRIPTION

[0071] The following is combined with Figure 1-7 The present invention is described in further detail.

[0072] In this embodiment, in order to solve the problem of the current lack of devices and methods for conducting electrostatic sensitivity tests on liquid material samples, the present invention discloses a liquid material electrostatic sensitivity test method based on surface discharge, comprising the following steps:

[0073] Step 1: Design and make a set of liquid material electrostatic sensitivity test equipment that can remotely control the charging capacitance and voltage and control the electrostatic discharge. It can be divided into three parts: remote control system, charging and discharging chamber, and experimental chamber (such as Figure 2As shown); the remote control module includes a host computer, which deploys the test control software and can remotely control the programmable high-voltage source, charging capacitor selection circuit, discharge main switch, electrode drive device, sample temperature control module and other mechanisms through optical fiber, network cable, etc., and perform the actions in sequence according to the program requirements to complete the liquid electrostatic sensitivity test; the charging and discharging cabin includes four modules or parts: programmable high-voltage source, discharge circuit, charging capacitor selection circuit, and discharge main switch. The programmable high-voltage source charges the capacitor selected in the charging capacitor selection circuit, and the discharge main switch discharges the energy storage capacitor to the discharge circuit, and finally generates a spark discharge at the discharge gap; the experimental cabin part includes It contains five modules or parts, namely, an electrode driving device, a discharge gap (upper and lower electrodes), a sample temperature control module, a sample loading slot and a heating device, and a temperature measuring device. The discharge gap (upper and lower electrodes), the sample loading slot and the heating device constitute the loading module. The spark discharge generated by the discharge circuit is loaded into the discharge gap to stimulate the sample in the sample loading slot, which may cause it to respond or not respond. The electrode driving device adjusts the position of the upper electrode to adjust the size of the discharge gap. The temperature measuring device feeds back the temperature of the sample loading slot to the sample temperature control module and adjusts the heating device on the sample loading slot according to the set test temperature to control the sample temperature. The overall system composition is as follows: Figure 1 As shown, the yellow arrow represents the control route, and the blue arrow represents the charging and discharging route;

[0074] Step 2: Design and manufacture the sample loading module for liquid samples, namely the discharge gap (upper and lower electrodes) and sample loading tank and heating device in the experimental chamber in step 1, which consists of upper electrode, sample loading tank, lower electrode, semiconductor heating plate, fixed thread and other structures, such as Figure 3 As shown in the figure, during the electrostatic discharge process, the high-voltage switch controls the tip of the upper electrode to have a higher voltage (e.g., 10 kV), the ground potential of the lower electrode is kept at 0 V, and the liquid sample tank is filled with the liquid material to be tested. A large potential and uneven electric field distribution are generated at the liquid-air interface, thereby achieving surface discharge at the liquid-gas interface.

[0075] Step 3: Install the liquid material electrostatic sensitivity test device and the sample loading module, and ensure that the experimental cabin in front of the sample loading module is transparent and unobstructed (bullet-proof glass can be used for protection), arrange a high frame rate camera in front of the sample loading module, and debug the overall test system (such as Figure 7 shown);

[0076] Step 4: Determine the maximum charging capacitance, maximum charging voltage, minimum charging capacitance, and minimum charging voltage based on the test device, calculate the corresponding capacitive energy storage settings as the upper and lower limits of the test, and determine the test number, test temperature (default 30°C), electrode gap (the distance from the upper electrode to the bottom of the sample loading tank, default 1.2mm) and other test setting parameters based on the test requirements;

[0077] Step 5: Based on the Langley-Optimized D method and the test data (the first time is based on the upper and lower limits), calculate and set the single test parameters such as the electrostatic charging capacitance and voltage for this test;

[0078] Step 6: In addition to the first test, the remaining samples in the sample loading tank need to be cleaned. Use a pipette gun or other liquid transfer mechanism to add the liquid material sample to the sample loading tank in the loading module, ensuring that the liquid level is flush with or slightly lower than the edge of the sample loading tank. Close the safety door of the experimental cabin and evacuate personnel to a safe location to achieve human-machine isolation. The experimental system is arranged as follows: Figure 7 As shown;

[0079] Step 7: Run the high frame rate camera and set the parameters to remotely control the recording. Run the software on the host control computer to remotely control the electrostatic discharge of the test device. Use the video data recorded by the high frame rate camera to determine whether the sample responds.

[0080] Step 8: Repeat steps 5 to 7 until the number of tests meets the requirement;

[0081] Step 9: Based on the "maximum likelihood method", calculate the electrostatic sensitivity distribution of the liquid material to be tested according to the set charging energy and response of each test. Assuming that its electrostatic sensitivity distribution is log-normal, the calculation method is to optimize the mean μ and standard deviation σ to maximize the probability P of the pre-test result. The Newton method can be used to iteratively solve its maximum value point. The specific calculation process is as follows: Figure 4 As shown, the specific process is introduced in the specific implementation plan of Part VII.

[0082] It should be added that the sample loading module includes the discharge gap, sample loading slot and heating device in the experimental chamber in step 1. The sample loading module is specifically composed of an upper electrode, a sample loading slot, a lower electrode, a semiconductor heating plate, a fixed thread and a grounding wire. During the electrostatic discharge process, the high-voltage switch controls the tip of the upper electrode to have a higher voltage, and the ground potential of the lower electrode is maintained at 0V. The liquid sample loading slot is filled with the liquid material to be tested, and a large potential and uneven electric field distribution are generated at the liquid-air interface, thereby realizing surface discharge at the liquid-gas interface.

[0083] It should be added that the upper electrode is made of stainless steel, has a pointed tip, and its upper portion is connected to the driving electrode via a polytetrafluoroethylene column.

[0084] It should be added that the sample loading tank is made of copper as the base material, with silver-plated surface, the sample loading tank has a diameter of 8 mm, a depth of 1.2 mm, and a top distance of 7 mm from the semiconductor heating plate (such as Figure 6 shown).

[0085] It should be added that the specific calculation steps of the "maximum likelihood method" in step 9 are as follows: Step 9.1: Record the charging energy E of all k trialsCi , and calculate the corresponding electrostatic stimulation amount x i =log(E Ci ), record the response v corresponding to all experiments i ;

[0086] Step 9.2: Determine the allowable error ε for parameter estimation and begin iteratively solving the maximum probability point of the test results based on the "Newton method";

[0087] Step 9.3: Find the corresponding v i =1 is denoted as x 1L , find the corresponding v i =0 is recorded as x 0U , change x 1L and x 0U The number of stimulus amounts between m , and thus determine the initial value of the iterative calculation:

[0088]

[0089] Where: μ (0) Iterative initial value of the electrostatic sensitivity mean value;

[0090] σ (0) Iterative initial value of electrostatic sensitivity standard deviation;

[0091] k total number of trials;

[0092] x 1L Minimum response stimulus amount;

[0093] x 0U Maximum non-response stimulus amount;

[0094] n m The number of stimulus amounts in the mixed interval;

[0095] Step 9.4: Calculate the following intermediate variables in sequence:

[0096]

[0097]

[0098] Where: t is the number of iteration steps;

[0099] iDifferent test numbers;

[0100] u normal distribution coordination number;

[0101] p electrostatic sensitivity response probability;

[0102] Other parameters are used to calculate intermediate variables;

[0103] Step 9.5: Solve the two-variable equation system to obtain the change in the distribution parameters:

[0104]

[0105] Where: Δμ (t) Iterative increase of the mean value of sensitivity distribution;

[0106] Δσ (t) Iterative increase in the standard deviation of sensitivity distribution;

[0107] Step 9.6: Determine and suppress excessive changes: Ensure |Δμ (t) |<σ (t-1) And σ (t-1) / 2<Δσ (t) <2Δσ (t-1) If it is not satisfied, the change must be limited to this range;

[0108] Step 9.7: Add the mean and standard deviation of the electrostatic sensitivity distribution to the change to complete one iteration;

[0109] Step 9.8: Determine whether the sum of the absolute values of the two parameter changes is less than the allowable error ε. If not, repeat steps 9.4 to 9.7.

[0110] Step 9.9: Output the mean μ and standard deviation σ, and calculate the electrostatic discharge energy corresponding to different response probabilities.

[0111] It should also be added that the specific steps for setting the test parameters in step 4 are:

[0112] Step 4.1: Run the laptop in the remote control system, connect the optical fiber and the optical terminal power supply, connect the optical fiber and the high-voltage source USB cable to the charging and discharging compartment, and then turn on the computer and the charging and discharging compartment power switches.

[0113] Step 4.2: Run the measurement and control program "Electrostatic Inductance Tester" shortcut icon in the liquid electrostatic sensitivity test device control computer, and then double-click to open the software. After the software interface opens, the experimental chamber electrode will automatically "return to zero" and eventually stop at a zero point 15mm above the discharge lower electrode. If a red error appears in the software interface or the electrode does not move, you need to exit the software and restart the device and software.

[0114] Step 4.3: Set up in the "Electrostatic Inductance Tester" software: According to the test requirements, reasonably set the reagent test temperature (default 30℃), data acquisition parameters (default original value), electrode gap (default 1.2mm) and other parameters.

[0115] Step 4.4: Connect the high-frame-rate camera to the power supply and run the "RCC" software on the laptop. In preview mode, set the capture frame rate to 50 fps and the exposure time to 9995 μs. Fine-tune the lens focus to ensure that the sample loading slot and the discharge electrode are in clear focus, and set the intelligent trigger mode.

[0116] Step 4.5: Run the "Explosives and Pyrotechnics Electrostatic Sensitivity Test Program Software" V2.6 [Explosives and Pyrotechnics Electrostatic Sensitivity Test Program Software V1.1 copyright licensed, registration number: 2023SR0740623]. Click "Test Capacitor Channel" in the left menu bar. Set the capacitance values for different channels based on the energy storage capacitors in the liquid sample electrostatic sensitivity test device. Select "Add Test" in the "Test" menu bar on the left. Enter the sample parameters based on the sample information. Measure the ambient temperature and humidity using a thermometer and hygrometer, then enter the environmental parameters. In the test parameters, set the total number of tests to 100 and the number of baseline tests to 0. Set the capacitance lower limit to the lowest value of the combination, the capacitance upper limit to the highest value of the combination, the voltage lower limit to 3 kV, the voltage upper limit to 18 kV, the transformation type to "Logarithmic Transformation", the sensitivity distribution curve to "Normal Distribution", select "Call the Lower Computer" (No), select "Record Actual Spark Energy" (Yes), and select "Langley-Optimized D Method" for all algorithms. After completing the settings, click Confirm.

[0117] The specific steps for setting the single test parameters in step 5 are as follows:

[0118] Step 5.1: Access the established tests in the "Explosives and Pyrotechnics Electrostatic Sensitivity Test Program Software" and click Add Test. The program calculates the recommended values for this test based on the existing test data using the "Langley-Optimized D" method mathematical statistics model. Select an adjustable capacitance value for the liquid electrostatic sensitivity test device from the program's recommended capacitance energy storage range (the total capacitance of multiple channels simultaneously turned on is equivalent to the sum of the capacitance values of each channel) and enter it. The program then displays the recommended charging voltage value.

[0119] Step 5.2: Set the high-voltage source output and relay channel (i.e., capacitance and combination) for this test on the "Electrostatic Inductance Tester" program interface according to the output value.

[0120] In step 6, sample cleaning and loading operation method:

[0121] Step 6.1: Use alcohol cotton to clean the experimental chamber, focusing on cleaning the samples that may remain in the lower electrode sample loading slot and the samples sprayed on the walls and bottom of the experimental chamber, and properly place the cleaned alcohol cotton and absorbent cotton in the explosion-proof tank (or other protective structure) in the explosion-proof room.

[0122] Step 6.2: Adjust the pipette to the required liquid volume (default 30 μL) according to the size of the sample loading tank.

[0123] Step 6.4: Use a pipette to draw the required liquid from the pipette holder and inject it all into the lower electrode sample loading tank.

[0124] Step 6.4: After the injection is completed, close the safety door. When the green light comes on, personnel evacuate to the control room where the laptop is located before conducting subsequent tests.

[0125] The specific steps for remote control electrostatic discharge in step 7 are as follows:

[0126] Step 7.1: Click “Auto Test” on the “Electrostatic Inductance Tester” program interface. The mobile electrode will automatically move to the set electrode gap position and automatically start “charging” and “discharging” after the temperature reaches the set temperature.

[0127] Step 7.2: Observe the running status of the "RCC" software. If it is still recording and fails to trigger normally, after eliminating abnormal conditions such as lens obstruction and viewing angle error, it can be determined that the sample has not responded. If the software is triggered normally, enter the playback interface to replay the electrostatic discharge process frame by frame. If there is only white or blue flash in the video image without flame (the color and specific phenomenon are determined according to the actual situation on site) or sparks, then this test has not responded; on the contrary, if flames, sparks, etc. appear in the image, then this test has responded. At the same time, the tester can also make a comprehensive judgment on the response situation based on whether there is an explosion sound and sample residue on site, and typical response and non-response image conditions.

[0128] Step 7.3: Enter the response obtained using the "RCC" software into the "Explosives and Pyrotechnics Electrostatic Sensitivity Test Program Software", describe the test phenomenon, and click Confirm.

[0129] The specific steps for analyzing the liquid material electrostatic sensitivity test data in step 9 are as follows:

[0130] In the "Explosives and Pyrotechnics Electrostatic Sensitivity Test Program Software", click "Test Data View" in the left menu bar, select the electrostatic sensitivity test that just ended (usually appears in the first row, number 1), click "View Test", and select "Test Results" on the tab page. The software will calculate the electrostatic sensitivity distribution of the tested sample based on the "maximum likelihood principle". Figure 4 For the specific calculation steps, please refer to the above-mentioned "maximum likelihood method" calculation steps.

[0131] In the upper part of the "View Test Results" page, for electrostatic safety threshold query, enter the response probability corresponding to the safety threshold to be queried (in %). Multiple query values are separated by English commas (for example, "50,1,0.01,0.0001"), and enter the confidence probability to display the confidence interval (in %). Multiple variable input is not supported (for example, "95"). After selecting the actual spark energy, click Query. The safety threshold and confidence interval corresponding to the response probability will be displayed in the table.

[0132] In the lower part of the "View Test Results" page, adjust the three test result graphs of "Test Record", "Sensitivity Distribution" and "Safety Threshold". The x-axis coordinate range, y-axis coordinate range, whether to display logarithmically, legend position, etc. can all be adjusted in the settings menu on the right. Each picture can be saved by clicking the "three" icon in the upper right corner of the picture.

[0133] After completing the above operations, click "Save Test Results" in the upper right corner of the page to return to the test result viewing interface. Choose whether to export the test results (export to Excel format) as needed, end the test, analyze the test results, and write a test report.

[0134] The electrostatic sensitivity test method of the present invention is applicable to liquid material samples. During the test, test parameters such as charging capacitance, voltage, sample temperature, and electrode gap can be adjusted by a host computer program. The electrostatic discharge process achieves human-machine isolation, providing a high degree of inherent safety. The electrostatic sensitivity test method for liquid materials is standardized through a specific operating process. Therefore, the present invention solves the three deficiencies of existing explosion location methods mentioned in the technical background and can achieve:

[0135] (1) Electrostatic sensitivity test of liquid samples can be carried out

[0136] This method is based on the surface discharge theory and proposes an electrostatic sensitivity test method that forms an electrostatic spark discharge path at the interface between the liquid material and the air. A large asymmetric distribution of electric potential and electric field strength is formed at the interface between the liquid material and the air, breaking through the liquid-gas interface to form an electrostatic spark discharge path, thereby realizing the electrostatic sensitivity test of liquid materials for the first time. Figure 5 shown.

[0137] (2) Program-controlled adjustment of test parameters such as charging capacitor voltage and sample temperature

[0138] The electrostatic sensitivity test device designed and manufactured in the present invention has multiple electrostatic charging capacitors, which are connected through a high-voltage switching switch. The high-voltage switch can be controlled by a relay through a host computer to select the charging capacitor; at the same time, a programmable high-voltage power supply is adopted in the design, and the charging voltage can be adjusted by the host computer software program through optical fiber communication; a stepper motor is used in the design to adjust the electrode position and electrode gap, which can also be precisely controlled by the control signal transmitted from the optical fiber by the host computer; a semiconductor temperature control module is used in the design, and the sample temperature can be precisely controlled by the host computer through the optical fiber.

[0139] (3) Realize human-machine isolation during electrostatic discharge

[0140] The safety door of the experimental chamber of this invention features a human-machine interlock function. When the safety door is open, a red indicator light illuminates, preventing electrostatic discharge. This ensures that when personnel open the safety door to load liquid samples or clean samples, there is no accidental electrostatic discharge, which could ignite residual samples and cause casualties. Furthermore, the experimental device is controlled by a host computer via fiber-optic communication, with a maximum transmission distance of 10 meters. This allows the experimental chamber to be placed in an explosion-proof room, allowing personnel to operate remotely through a wall, thus ensuring human-machine isolation during the electrostatic discharge process.

[0141] Secondly, it should be noted that:

[0142] 1. The split design of the charging and discharging chamber and the experimental chamber in step 1 is not necessary. All modules in the two parts can be built together, or divided into more parts to form a box, which will not affect the operation of the overall liquid sensitivity test device;

[0143] 2. The order of steps 1 and 2, steps 3 and 4, and steps 5 and 6 can be swapped without affecting the overall test process;

[0144] 3. In step 5, replacing the "Langley-Optimized D" method with other electrostatic sensitivity test mathematical statistics methods such as the "lift and drop method", "Langley method", "optimal information matrix method", "quartile convergence method", "probit method", "OSTR method", etc. may affect the test efficiency and the accuracy of the test results, but does not affect the core content of the present invention, that is, to carry out the electrostatic sensitivity test of liquid materials;

[0145] 4. In step 6, replacing the pipette with a syringe or other pipetting mechanism does not affect the overall test process;

[0146] 5. If the test dose is assessed to be fully contained in the test chamber in step 6, personnel do not need to evacuate to other rooms, while still meeting the safety requirements of human-machine isolation during the test process;

[0147] 6. The high frame rate camera in step 3 can be replaced with an infrared camera, high-frequency microphone, etc. to monitor infrared temperature or sound signals for judgment based on the sample response characteristics. This may affect the accuracy of the test results, but will not affect the core connotation of the present invention;

[0148] 7. When designing the sample loading module in step 2, the position of the semiconductor heater can be moved up or down, as long as the internal heating circuit is insulated from the metal lower electrode, which will not affect the overall test process.

[0149] Surface discharge: refers to the discharge phenomenon along the interface between dielectrics of different aggregate states. In the present invention, it specifically refers to the surface discharge generated at the interface between gas and liquid dielectrics.

[0150] Electrostatic sensitivity: Electrostatic sensitivity refers to the ease with which a sample burns or explodes when exposed to electrostatic discharge sparks.

[0151] Electrostatic sensitivity test: refers to the test process of conducting a series of electrostatic discharge tests on samples based on specific mathematical and statistical methods, and obtaining the electrostatic sensitivity of the sample based on whether it responds.

[0152] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A liquid material electrostatic sensitivity test method based on surface discharge, characterized in that: The following steps are involved: Step 1: Design and manufacture a liquid material electrostatic sensitivity test device that can remotely adjust the charging capacitance and voltage and control electrostatic discharge. The device consists of three parts: a remote control system, a charging and discharging chamber, and a test chamber. Step 2: Design and manufacture a sample loading module for liquid samples to achieve an uneven electric field distribution at the liquid-air interface; Step 3: Install and lay out the liquid material electrostatic sensitivity test device and the sample loading module, and ensure that the experimental cabin in front of the sample loading module is transparent and unobstructed. Place a high-frame rate camera in front of the sample loading module, and debug the entire test system. Step 4: Determine the maximum charging capacitance, maximum charging voltage, minimum charging capacitance, and minimum charging voltage based on the test device, calculate the corresponding capacitance energy storage settings as the upper and lower limits of the test, and determine the test number, test temperature, electrode gap and other test setting parameters based on the test requirements; Step 5: Based on the Langley-Optimized D method and the test data, calculate and set the single test parameters such as electrostatic charging capacitance and voltage for this test; Step 6: Except for the first test, the remaining sample in the sample loading tank needs to be cleaned. Use a pipette or other pipetting mechanism to add the liquid material sample to the sample loading tank in the loading module, ensuring that the liquid level is flush with or slightly lower than the edge of the sample loading tank. Close the safety door of the experimental cabin and evacuate personnel to a safe location to achieve human-machine isolation; Step 7: Run the high frame rate camera and set the parameters to remotely control the recording. Run the software on the host control computer to remotely control the electrostatic discharge of the test device. Use the video data recorded by the high frame rate camera to determine whether the sample responds. Step 8: Repeat steps 5 to 7 until the number of tests meets the requirement; Step 9: Based on the maximum likelihood method, calculate the electrostatic sensitivity distribution of the liquid material to be tested according to the set charging energy and response of each test. Assuming that its electrostatic sensitivity distribution is log-normal, the calculation method is to optimize the mean μ and standard deviation σ to maximize the probability P of the pre-test result. The Newton method is used to iteratively solve its maximum value point. The specific calculation steps of the "maximum likelihood method" in step 9 are as follows: Step 9.1: Record the charging energy E of all k trials Ci , and calculate the corresponding electrostatic stimulation amount x i =log(E Ci ), record the response v corresponding to all experiments i ; Step 9.2: Determine the allowable error ε for parameter estimation and begin iteratively solving the maximum probability point of the test results based on the "Newton method"; Step 9.3: Find the corresponding v i =1 is denoted as x 1L , find the corresponding v i =0 is recorded as x 0U , x 1L and x 0U The number of stimulus amounts between m , and thus determine the initial value of the iterative calculation: Where: μ (0) Iterative initial value of the electrostatic sensitivity mean value; σ (0) Iterative initial value of electrostatic sensitivity standard deviation; k total number of trials; x 1L Minimum response stimulus amount; x 0U Maximum non-response stimulus amount; n m The number of stimulus amounts in the mixed interval; Step 9.4: Calculate the following intermediate variables in sequence: Where: t is the number of iteration steps; iDifferent test numbers; u normal distribution coordination number; p electrostatic sensitivity response probability; Other parameters are used to calculate intermediate variables; Step 9.5: Solve the two-variable equation system to obtain the change in the distribution parameters: Where: Δμ (t) Iterative increase of the mean value of sensitivity distribution; Δσ (t) Iterative increase in the standard deviation of sensitivity distribution; Step 9.6: Determine and suppress excessive changes: Ensure |Δμ (t) |<σ (t-1) And σ (t-1) / 2<Δσ (t) <2Δσ (t-1) If it is not satisfied, the change must be limited to this range; Step 9.7: Add the mean and standard deviation of the electrostatic sensitivity distribution to the change to complete one iteration; Step 9.8: Determine whether the sum of the absolute values of the two parameter changes is less than the allowable error ε. If not, repeat steps 9.4 to 9.

7. Step 9.9: Output the mean μ and standard deviation σ, and calculate the electrostatic discharge energy corresponding to different response probabilities.

2. The electrostatic sensitivity test method of liquid materials based on surface discharge according to claim 1, characterized in that: In step 1, the remote control system includes a host computer, which deploys test control software and remotely controls the programmable high-voltage source, charging capacitor selection circuit, discharge main switch, electrode drive device, sample temperature control module and other mechanisms through optical fiber, network cable, etc., and performs operations in sequence according to program requirements to complete the liquid electrostatic sensitivity test.

3. The electrostatic sensitivity test method of liquid materials based on surface discharge according to claim 2, characterized in that: In step 1, the charging and discharging chamber includes four modules or parts: a programmable high-voltage source, a discharge circuit, a charging capacitor selection circuit, and a discharge main switch.

4. The method for testing electrostatic sensitivity of liquid materials based on surface discharge according to claim 3, characterized in that: In step 1, the experimental chamber portion includes five modules or parts, namely, an electrode driving device, a discharge gap, a sample temperature control module, a sample loading slot and a heating device, and a temperature measuring device. The discharge gap, the sample loading slot and the heating device constitute the loading module. The spark discharge generated by the discharge circuit is loaded into the discharge gap to stimulate the sample in the sample loading slot, which may cause it to respond or not respond. The electrode driving device adjusts the position of the upper electrode to adjust the size of the discharge gap. The temperature measuring device feeds back the temperature of the sample loading slot to the sample temperature control module and adjusts the heating device on the sample loading slot according to the set test temperature to control the sample temperature.

5. The method for testing electrostatic sensitivity of liquid materials based on surface discharge according to claim 4, characterized in that: The charging capacitor selection circuit is composed of a high-voltage transfer switch and a discharge resistor. The main discharge switch is a high-voltage transfer switch, which is connected to the discharge resistor and finally connected to the upper electrode of the experimental cabin. High voltage transfer switches are all controlled by remote control systems; A charging resistor is connected in series between the programmable high voltage source and the main switch.

6. The method for testing electrostatic sensitivity of liquid materials based on surface discharge according to claim 1, characterized in that: In step 2, the sample loading module includes the discharge gap in the experimental chamber in step 1, the sample loading slot, and the heating device. The sample loading module is specifically composed of an upper electrode, a sample loading slot, a lower electrode, a semiconductor heating plate, a fixing thread, and a grounding wire. During the electrostatic discharge process, the high-voltage switch controls the tip of the upper electrode to have a higher voltage, and the ground potential of the lower electrode is maintained at 0V. The liquid sample loading slot is filled with the liquid material to be tested, and a large potential and uneven electric field distribution are generated at the liquid-air interface, thereby realizing surface discharge at the liquid-gas interface.

7. The method for testing electrostatic sensitivity of liquid materials based on surface discharge according to claim 6, characterized in that: The upper electrode is made of stainless steel and has a pointed tip. The upper portion is connected to the driving electrode via a polytetrafluoroethylene column.

8. The method for testing electrostatic sensitivity of liquid materials based on surface discharge according to claim 6, characterized in that: The sample loading tank is made of copper as the base material and the surface is silver-plated. The sample loading tank has a diameter of 8 mm, a depth of 1.2 mm, and a top distance of 7 mm from the semiconductor heating plate.

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