Liquid material electrostatic sensitivity test method based on creeping discharge

Abstract

The invention discloses a liquid material electrostatic sensitivity test method based on creeping discharge in the technical field of combustion explosive industry safety, and the method comprises the following steps: step 1, designing a liquid material electrostatic sensitivity test device for controlling electrostatic discharge; 2, designing and manufacturing a sample loading module for a liquid sample; 3, installing and laying a liquid material static sensitivity test device and a sample loading module; 4, determining group test setting parameters according to the test device; 5, setting single test setting parameters; 6, loading the liquid material sample into a sample loading module; 7, remotely controlling electrostatic discharge of the test device; 8, repeating the steps 5-7 until the test times meet the requirement; and step 9, calculating the static sensitivity distribution of the liquid material to be tested according to the set charging energy and the response condition of each test. The static sensitivity test method for the liquid material is relatively high in safety degree, and the static sensitivity test method for the liquid material is standardized through a specific operation process.

Description

Technical Field

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

[0002] Electrostatic sensitivity is a sensitivity index that characterizes the combustion and explosion characteristics of burning explosives. It is an important basic data for analyzing the ignition reliability of industrial explosives, and is also an important basis for evaluating the electrostatic safety risks of burning 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 material to be tested 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 characterize 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 characterize the electrostatic safety threshold, which is an important basis for evaluating the electrostatic safety risks of burning explosives during production, transportation, use, and destruction.

[0003] The electrostatic sensitivity test refers to the relationship between the amount of electrostatic stimulation applied and the response of the sample, which is a very complex issue. Existing studies have shown that it is impossible to obtain the minimum static ignition stimulus for a single sample through testing. The reason is that the static spark discharge ignition test is an extremely special destructive test. For a specific sample, only one test can be carried out to determine the static stimulus amount, 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 of electrostatic sensitivity test and found that the "Langley-Optimization D" method can be used to carry out electrostatic sensitivity test, and relatively accurate minimum and maximum response probabilities corresponding to critical electrostatic stimulation can be obtained, which can be used to evaluate the electrical ignition reliability and electrostatic safety risk of burning and explosive materials respectively [Sun Mingze, Wang Yanping, Luo Taiming, et al. Analysis and optimization of mathematical statistics methods for electrostatic sensitivity test 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 test and friction sensitivity test, but no specific test device design and test method guidance are provided for electrostatic sensitivity test.

[0005] The current domestic standards for the electrostatic sensitivity test of burning explosives can mainly refer to: National Military Standard for Explosive Test Standards (GJB772A-1997), National Military Standard for Safety Test Methods for Booster (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 (GJB8142-2013), National Military Standard for Test Methods for Initiating Pyrotechnics (GJB5891-2006). These test methods are only for powder and solid samples, and do not specify how to conduct electrostatic sensitivity tests 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 Institute proposed a solid engine electrostatic safety test device and method in 2016 [Sun Liqing, Liu Kai, Yuan Jun, et al. A solid engine 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 engine, thereby testing the electrostatic sensitivity of the solid engine; Rao Guoning from Nanjing University of Science and Technology et al. proposed a test device for testing the electrostatic sensitivity of the human body for burning explosives in 2019 [Rao Guoning, Ren Jiafan, Feng Bo, et al. A test device for testing the electrostatic sensitivity of the human body for burning explosives [P]. Jiangsu Province: CN201911088777.7, 2020-02-25.], which can simulate the generation and release of static electricity in the human body and measure the electrostatic sensitivity that is closer to the electrostatic discharge of the human body; Wu Guilin et al. of Sichuan Aerospace Metrology and Testing Institute proposed an electrostatic sensitivity spark discharge test device in 2022, which can simulate the generation and release of static electricity in the human body and measure the electrostatic sensitivity that is closer to the electrostatic discharge of the human body. The discharge gap is precisely adjustable [Wu Guilin, Yang Feng, Zhao Dan. A static 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 static sensitivity experimental device in 2023 [Ke Changzheng, Zheng Zhuangzhuang, Huang Cheng, et al. Aerosol static sensitivity experimental device [P]. Guangdong Province: CN202323261613.4, 2024-07-23 .], which can conduct electrostatic sensitivity tests on gas samples such as aerosols; 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 in 2023 [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 conduct electrostatic sensitivity tests under temperature coupling conditions for powder samples. The above electrostatic sensitivity test devices are only designed for solid, powder, and gas (aerosol) samples. There is currently a lack of devices that can conduct 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 programmatically adjust 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] (I) Not suitable for liquid samples

[0009] The above electrostatic sensitivity test devices are only designed for solid, powder, and gas (aerosol) samples. There is currently a lack of devices and methods that can carry out electrostatic sensitivity tests on liquid material samples. This is mainly because the electrostatic spark discharge mode of the existing electrostatic sensitivity test process is designed based on the gas breakdown discharge theory. A large potential difference is applied in a small gap. When the electrostatic electric field strength in the air is greater than the air breakdown electric field (generally 3kV / mm), it is possible to break through the air at the gap to form a plasma discharge channel and realize electrostatic spark discharge. For powder samples, due to the low packing density, there are enough air gaps between the powder particles, and electrostatic spark discharge is still achieved by breaking through these air gaps. The same process also exists for aerosol samples. The proportion of liquid particles in the air is relatively low, and electrostatic spark discharge is achieved by breaking through air gaps. For solid materials such as solid motors, they are usually compressed from powders, and there are pore structures inside. Under high electrostatic high pressure, local materials are polarized and broken down to form air passages, realizing 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 during the polarization process to form an air passage, and it is not easy to break down the liquid at both ends of the liquid material to generate electrostatic spark discharge.

[0010] (II) It is impossible to program and adjust the test parameters such as charging capacitor voltage and sample temperature

[0011] Existing electrostatic sensitivity test equipment is mainly designed for fixed charging circuits, that is, the charging capacitor and voltage are fixed and cannot be adjusted. A lower electrode structure that can adjust the sample test temperature is designed in the "lower electrode of a temperature-coupled powder electrostatic discharge sensitivity test system", and a mechanism that can accurately adjust the discharge electrode gap is designed in the "electrostatic sensitivity spark discharge test device", but neither of them implements upper computer software program control, and requires manual adjustment or individual device button adjustment. Therefore, it is impossible to achieve program-controlled adjustment of test parameters such as charging capacitor voltage and sample temperature, the test process is relatively cumbersome, and the test efficiency is low.

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

[0013] The sample response determination methods specified in the current GJB772A-1997, GJB2178-2005 and other test methods are all observation methods, which require manual observation of whether there is explosion fire during the test, manual monitoring of whether there is explosion sound, and manual identification of air temperature and participating samples after the test. It is impossible to achieve effective human-machine isolation during the electrostatic discharge process. The existing "A solid engine electrostatic safety test device and method" and other test device designs do not clearly define the human-machine isolation method and implementation structure. Personnel may need to operate close to perform electrostatic discharge, and the intrinsic safety level of the test device design is not high.

[0014] The present invention can provide a liquid material electrostatic sensitivity test method based on surface discharge, which can solve the above-mentioned problem and carry out electrostatic sensitivity test of liquid materials. During the test process, parameters such as charging capacitor voltage and temperature can be adjusted by program control, 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 the specification abstract and the invention title of the present invention to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot 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 problem of the current lack of devices and methods for conducting electrostatic sensitivity tests on liquid material samples.

[0017] The present invention proposes a liquid material electrostatic sensitivity test method based on surface discharge, comprising the following steps:

[0018] Step 1: Design and manufacture a set of liquid material electrostatic sensitivity test equipment that can remotely control the charging capacitance and voltage and control electrostatic discharge. It can be divided into three parts: remote control system, charging and discharging cabin, and experimental cabin;

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

[0020] Step 3: Install and set up 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, arrange a high frame rate camera in front of the sample loading module, and debug the overall test system;

[0021] Step 4: Determine the maximum charging capacitance, maximum charging voltage, minimum charging capacitance, and minimum charging voltage according to 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 according to the test requirements;

[0022] Step 5: Based on the Langley-Optimization D method and the test data that have been carried out, calculate and set the single test setting parameters such as electrostatic charging capacitance and voltage for this test;

[0023] Step 6: Except for the first test, the residual samples in the sample loading tank need to be cleaned, and the liquid material samples are added to the sample loading tank in the loading module using a pipette gun or other pipetting mechanism, ensuring that the liquid level is flush with or slightly lower than the edge of the sample loading tank, and the safety door of the experimental cabin is closed, and personnel are evacuated to a safe location to achieve human-machine isolation;

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

[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. It is assumed 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 Newton's method to iteratively solve its maximum point.

[0027] Preferably, 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 operates in sequence according to program requirements to complete the liquid electrostatic sensitivity test.

[0028] Preferably, in step 1, the charging and discharging compartment 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, wherein 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 cabin 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 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 grounding 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 part is connected to the driving electrode by 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 of 7 mm from the semiconductor heating plate.

[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 tests Ci , and calculate the corresponding electrostatic stimulation x i =log(E Ci ), record the response v corresponding to all tests i ;

[0037] Step 9.2: Determine the allowable error ε of parameter estimation, and start iterating to find 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 denoted 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) Iteration initial value of the mean value of electrostatic sensitivity;

[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 calculate intermediate variables;

[0053] Step 9.5: Solve the two-variable equation system to obtain the change in 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 should 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 changes of the two parameters 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 includes 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, 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 accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying 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 diagram of the structure 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 A schematic diagram of realizing electrostatic spark discharge by surface discharge at the liquid-air interface of the present invention;

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

[0070] Figure 7 It is the 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 electrostatic discharge. It can be divided into three parts: remote control system, charging and discharging cabin, and experimental cabin (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 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 make it 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 a sample loading module for liquid samples, i.e., the discharge gap (upper and lower electrodes) and sample loading slot and heating device in the experimental chamber in step 1, which consists of an upper electrode, a sample loading slot, a lower electrode, a semiconductor heating plate, a fixed thread, etc. Figure 3 As shown, during the electrostatic discharge process, the high-voltage switch controls the tip of the upper electrode to have a higher voltage (such as 10kV), the ground potential of the lower electrode is kept at 0V, and the liquid sample loading tank is filled with the liquid material to be tested, which generates a large potential and uneven electric field distribution at the liquid-air interface, thereby achieving surface discharge at the liquid-gas interface;

[0075] 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 (bulletproof 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 according to 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 (default 30°C), electrode gap (the distance from the upper electrode to the bottom of the sample loading slot, default 1.2mm) and other test setting parameters according to the test requirements;

[0077] Step 5: Based on the Langley-Optimization D method, according to the test data that has been carried out (the first time is based on the upper and lower limits), calculate and set the single test setting parameters such as electrostatic charging capacitance and voltage of this test;

[0078] Step 6: In addition to the first test, the residual samples in the sample loading tank need to be cleaned up. 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 to set parameters and remotely control the video recording. Run the software on the upper control computer to remotely control the electrostatic discharge of the test device. Determine whether the sample responds based on the video data recorded by the high frame rate camera.

[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", the electrostatic sensitivity distribution of the liquid material to be tested is calculated according to the set charging energy and response 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. 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 and sample loading slot and heating device part in the experimental cabin 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 grounding 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 the upper part is connected to the driving electrode by a polytetrafluoroethylene column.

[0084] It should be added that the sample loading groove is made of copper as the base material, 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 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 testsCi , and calculate the corresponding electrostatic stimulation x i =log(E Ci ), record the response v corresponding to all tests i ;

[0086] Step 9.2: Determine the allowable error ε of parameter estimation, and start iterating to find 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 denoted 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:

[0088]

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

[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 calculate intermediate variables;

[0103] Step 9.5: Solve the two-variable equation system to obtain the change in 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 should 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 changes of the two parameters 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 "ElectrostaticInductance Tester" shortcut icon in the control computer of the liquid electrostatic sensitivity test device, and then double-click to open the software. After the software interface is opened, the electrode in the experimental chamber will automatically "return to zero" and finally stop at the zero point 15mm above the lower discharge 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 in the "Electrostatic Inductance Tester" software: According to the test needs, reasonably set the reagent test temperature (default 30°C), data acquisition parameters (default original value), electrode gap (default 1.2mm) and other parameters.

[0115] Step 4.4: Connect the high frame rate camera power supply, run the "RCC" software on the laptop, set the shooting frame rate to 50fps and the exposure time to 9995μs in preview mode, fine-tune the lens focus to make the sample loading slot and the discharge electrode needle in focus, and set the smart trigger mode.

[0116] Step 4.5: Run the "Explosives and Fires Electrostatic Sensitivity Test Program Software" V2.6 [Explosives and Fires Electrostatic Sensitivity Test Program Software V1.1 software copyright has been authorized, registration number: 2023SR0740623], click the "Test Capacitor Channel" setting in the left menu bar, set the capacitance values ​​of different paths according to the built-in energy storage capacitor value in the liquid sample electrostatic sensitivity test device, select Add Test in the test in the left menu bar of the "Explosives and Fires Electrostatic Sensitivity Test Program Software", enter the sample parameters according to the sample information, use the thermometer and hygrometer to measure the ambient temperature and humidity and then enter the environmental parameters, set the total number of tests to 100 times in the test parameters, the bottom test to 0 times, select the capacitance lower limit as the lowest value of the combination, the capacitance upper limit as the highest value of the combination, the voltage lower limit 3kV, the voltage upper limit 18kV, the transformation type is "logarithmic transformation", the sensitivity distribution curve is "normal distribution", whether to call the lower computer select No, whether to record the real spark energy select Yes, all algorithms are "Langley-Optimization D method", and click Confirm after the settings are completed.

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

[0118] Step 5.1: Enter the established test of "Explosives and Fire Materials Electrostatic Sensitivity Test Program Software", click Add Test, the program calculates the recommended value for this test based on the "Langley-Optimization D" method mathematical statistics model based on the existing test data, select an adjustable capacitance value of a liquid electrostatic sensitivity test device from the capacitor energy storage range recommended by the program (the total capacitance value of multi-channel capacitors turned on at the same time is equivalent to the sum of the capacitance values ​​of each channel) and enter it, the program further displays the recommended value of the charging voltage.

[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] Procedure for cleaning and loading the sample in step 6:

[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 four 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 extract the required liquid from the pipette holder and inject it all into the lower electrode sample loading slot.

[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 of remote control for 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 cannot be triggered normally, after eliminating abnormal conditions such as lens occlusion 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 and other phenomena appear in the image, then this test has responded. At the same time, the test personnel 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 Fire Materials Electrostatic Sensitivity Test Program Software", click "Test Data View" in the left menu bar, select the electrostatic sensitivity test that has 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" and 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 %, separate multiple query values ​​with English commas (such as "50,1,0.01,0.0001"), and enter the confidence probability of the displayed confidence interval, in %, multiple variable input is not supported (such as "95"), select the actual spark energy and 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 can be applied 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 control. The electrostatic discharge process achieves human-machine isolation, and the intrinsic safety level is high. The electrostatic sensitivity test method of liquid materials is standardized through a specific operation process. Therefore, the present invention solves the three deficiencies of the existing explosion location method mentioned in the technical background, and can achieve:

[0135] (I) 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] (II) 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 is equipped with multiple electrostatic charging capacitors, which are connected through a high-voltage switching switch, and the high-voltage switch can be controlled by a host computer using a relay 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 controlled and adjusted by the host computer software program through optical fiber communication; a stepper motor is adopted in the design to adjust the electrode position and the electrode gap, which can also be accurately controlled by the control signal transmitted from the optical fiber by the host computer; a semiconductor temperature control module is adopted in the design, and the sample temperature can be accurately controlled by the host computer through the optical fiber.

[0139] (III) Realizing human-machine isolation during electrostatic discharge

[0140] The safety door of the experimental cabin of the present invention is equipped with a human-machine interlocking function. When the safety door is opened, the red indicator light is on, and electrostatic discharge cannot be performed. This can ensure that when personnel open the safety door to load liquid samples and clean samples, there will be no accidental electrostatic discharge, which may ignite residual samples and cause safety hazards such as casualties. At the same time, the test device is controlled by the host computer through optical fiber communication, and the maximum transmission distance can reach 10m. The experimental cabin can be placed in an explosion-proof room, and personnel can operate remotely through the wall, thereby 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 does not affect the operation of the overall liquid sensitivity test device;

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

[0144] 3. In step 5, the "Langley-optimized D" method is replaced by other mathematical statistics methods for electrostatic sensitivity tests such as the "lift and drop method", "Langley method", "optimal information matrix method", "quartile convergence method", "probability unit method", "OSTR" method, etc., which may affect the test efficiency and the accuracy of the test results, but does not affect the core connotation of the present invention, that is, to carry out electrostatic sensitivity tests on liquid materials;

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

[0146] 5. In step 6, if the test drug volume can be fully protected by the experimental cabin, the personnel do not need to evacuate to other rooms, but the safety requirements of human-machine isolation during the test process are still met;

[0147] 6. The high frame rate camera in step 3 can be replaced by an infrared camera, a high-frequency microphone, etc. to monitor infrared temperature measurement or sound signals for judgment according to the sample response characteristics, which 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 heating plate 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 of dielectrics with 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 samples based on whether they respond.

[0152] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope 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 protection scope 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 set of liquid material electrostatic sensitivity test equipment that can remotely control the charging capacitance and voltage and control electrostatic discharge. It is divided into three parts: remote control system, charging and discharging cabin, and experimental cabin; Step 2: Design and manufacture a sample loading module for liquid samples to achieve an uneven distribution of the electric field at the liquid-air interface; Step 3: Install and set up 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, arrange a high frame rate camera in front of the sample loading module, and debug the overall test system; Step 4: Determine the maximum charging capacitance, maximum charging voltage, minimum charging capacitance, and minimum charging voltage according to 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 according to the test requirements; Step 5: Based on the "Langley-Optimization D Method" and the test data that have been carried out, calculate and set the single test setting parameters such as electrostatic charging capacitance and voltage for this test; Step 6: Except for the first test, the residual samples in the sample loading tank need to be cleaned, and the liquid material samples are added to the sample loading tank in the loading module using a pipette gun or other pipetting mechanism, ensuring that the liquid level is flush with or slightly lower than the edge of the sample loading tank, and the safety door of the experimental cabin is closed, and personnel are evacuated to a safe location to achieve human-machine isolation; Step 7: Run the high frame rate camera to set parameters and remotely control the video recording. Run the software on the upper control computer to remotely control the electrostatic discharge of the test device. Determine whether the sample responds based on the video data recorded by the high frame rate camera. Step 8: Repeat steps 5 to 7 until the number of tests meets the requirement; 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 of each test. It is assumed 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.

2. A liquid material electrostatic sensitivity test method 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 operates in sequence according to the program requirements to complete the liquid electrostatic sensitivity test.

3. A liquid material electrostatic sensitivity test method 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 electrostatic sensitivity test method of liquid materials based on surface discharge according to claim 3 is characterized in that: 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.

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 conversion switch and a discharge resistor. The main discharge switch is a high-voltage conversion 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 liquid material electrostatic sensitivity test method based on surface discharge according to claim 1, characterized in that: In the step 2, the sample loading module includes the discharge gap in the experimental cabin 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 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 grounding 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. A liquid material electrostatic sensitivity test method based on surface discharge according to claim 6, characterized in that: The upper electrode is made of stainless steel and has a pointed tip, and the upper part is connected to the driving electrode by 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 groove is made of copper as the base material and the surface is silver-plated. The diameter of the sample loading groove is 8 mm, the depth is 1.2 mm, and the top is 7 mm away from the semiconductor heating plate.

9. The method for testing electrostatic sensitivity of liquid materials based on surface discharge according to claim 1, characterized in 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 tests Ci , and calculate the corresponding electrostatic stimulation x i =log(E Ci ), record the response v corresponding to all tests i ; Step 9.2: Determine the allowable error ε of parameter estimation, and start iterating based on the "Newton method" to find the maximum probability point of the test results; Step 9.3: Find the corresponding v i =1 is denoted as x 1L , find the corresponding v i =0 is denoted 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) Iteration initial value of the mean value of electrostatic sensitivity; 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 calculate intermediate variables; Step 9.5: Solve the two-variable equation system to obtain the change in 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 should 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 changes of the two parameters 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.

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