Automatic gas sampling method

Abstract

This invention belongs to the field of gas sampling and analysis, specifically relating to an automated gas sampling method aimed at solving problems such as dead volume interference in sampling pipelines and residual harmful gases. The method utilizes a controller to link the injection, nitrogen, sampling, and vacuum electric ball valves, constructing a fluid channel through a four-way pipe joint. The specific steps are as follows: after environmental initialization, vacuum extraction and dynamic flushing circulation of sample gas are used to replace the dead volume in the pipeline; the injection and sampling valves are opened for multi-stage filtration sampling, with the filter components intercepting particulate matter and blockage monitoring based on pressure slope analysis; after sampling, high-pressure nitrogen is used to backwash the filter components, replacing residual gas with inert gas. This invention eliminates impurity interference through automated control, significantly improving sampling purity and analytical accuracy, while effectively intercepting toxic dust and preventing harmful gas leakage, ensuring operational safety.

Description

Technical Field

[0001] This invention belongs to the field of gas sampling and analysis, and specifically relates to an automatic gas sampling method. Background Technology

[0002] As power systems develop towards higher voltage and larger capacity, the safe operation of high-voltage electrical equipment has become a key factor in ensuring grid stability. Sulfur hexafluoride (SF6) gas, with its excellent insulation and arc-quenching properties, is widely used in circuit breakers, instrument transformers, and gas-insulated fully enclosed switchgear. By sampling and analyzing the gas inside the equipment, technicians can monitor the insulation status of the electrical equipment in real time and detect any overheating or discharge faults. This has become an indispensable technical means in the operation and maintenance management system of power equipment.

[0003] Among these technologies, automated gas sampling technology serves as the core approach for obtaining samples of insulating media. It aims to achieve non-destructive gas collection through a precisely controlled pipeline system and automated logic. The basic principle of this technology is to use differential pressure or mechanical suction to guide gas from specific locations within electrical equipment into a pre-set sampling container, ensuring stable pressure and intact composition during the sampling process, thus providing representative original samples for subsequent laboratory testing.

[0004] However, existing technologies still face significant challenges in practical operation. Dead volume gases commonly present in sampling pipelines easily mix with target samples, leading to compromised sampling purity and severe deviations in analytical results. Furthermore, after operation, high concentrations of sample gases or hazardous decomposition products often remain inside the pipelines. Without effective cleaning and replacement mechanisms, harmful gas leaks can easily occur during device recovery or reuse, threatening the safety of the operating environment. In addition, the highly toxic dust produced by the decomposition of sulfur hexafluoride under high-temperature electric arcs can easily enter the sampling channel with the airflow. If efficient filtration and interception cannot be achieved at the sampling front end, it will not only cause pipeline contamination and cross-interference but also pose health hazards to personnel subsequently handling the samples. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic gas sampling method that can effectively solve the objectively existing technical problems mentioned in the background section.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an automatic gas sampling method, which is executed using a device including a controller, an electric ball valve for injection, an electric ball valve for nitrogen, an electric ball valve for sampling, a vacuum electric ball valve, and a four-way pipe connector, specifically including the following steps: Step 1: System initialization and environment preset. The controller obtains power from the mobile power supply and starts up. It detects the initial state of the sample injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve, and the vacuum electric ball valve to ensure that the sample injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve, and the vacuum electric ball valve are all in a fully closed state. At the same time, it collects the initial signal of the pressure sensor connected to the sampling electric ball valve. Step 2: The dead volume gas in the pipeline is automatically vented. After receiving the venting command, the controller controls the vacuum electric ball valve and the nitrogen electric ball valve to open, establishing a venting channel. The residual gas in the pipeline is guided into the vacuum waste gas cylinder through the four-way pipe joint. Then, the opening and closing states of the sample electric ball valve and the vacuum electric ball valve are alternately switched according to the preset logic. The dynamic flushing effect of the sample gas is used to circulate and replace the dead volume gas in the pipeline until the gas composition in the pipeline and the composition of the target gas to be sampled reach the preset consistency threshold. Step 3: Multi-stage filtration and sampling of sample gas. After receiving the sampling command, the controller simultaneously opens the injection ball valve and the sampling ball valve while keeping the nitrogen electric ball valve and the vacuum electric ball valve closed. The gas to be sampled enters the first connecting pipe through the injection tube and is intercepted by the filter assembly set at the cut-off point of the first connecting pipe. The filtered clean gas enters the vacuum sampling bottle through the four-way pipe joint and the third connecting pipe until the pressure value monitored by the pressure sensor reaches the preset balance range. Step 4: Sampling status monitoring and safety warning. During the sampling process, the controller receives the pressure data from the pressure sensor in real time and performs slope analysis. If the pressure data does not change within a specific time and the value is greater than the preset blockage threshold, it is determined that the pipeline is blocked. The controller immediately triggers the alarm module and lights up the red indicator light to remind the operator. Step 5: Pipeline cleaning and hazardous residue replacement. After sampling, the controller executes the cleaning program, opens the nitrogen electric ball valve to guide high-pressure nitrogen into the system, and backwashes the filter components in the first connecting pipe through the four-way pipe joint, and forces the stripped impurities into the vacuum waste gas cylinder. Then, high-pressure nitrogen is used to repeatedly fill and empty all connecting pipes to replace the residual sample gas with inert gas. Finally, all electric ball valves are closed to complete the operation.

[0007] Preferably, the controller includes a central processing unit, a storage module, a signal acquisition module, and a drive control module. The central processing unit is bidirectionally electrically connected to the storage module and is used to store preset logic control timing and pressure threshold parameters. The signal acquisition module is connected to the voltage monitoring circuits of the pressure sensor and the mobile power supply, respectively, and converts analog signals into digital signals before transmitting them to the central processing unit. The drive control module outputs drive current to the sample injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve, and the vacuum electric ball valve according to the instructions of the central processing unit, thereby achieving precise opening and closing control of the valves.

[0008] Preferably, the first, second, third, and fourth connecting pipes are all made of corrosion-resistant metal, and their inner walls are electrochemically polished to reduce the adsorption effect of gas molecules. One end of each of the first, second, third, and fourth connecting pipes is fixedly connected to one of the four ports of the four-way connector, and the other end is respectively connected to the output ports of the sample injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve, and the vacuum electric ball valve, forming a symmetrical cross-shaped fluid distribution structure to minimize local resistance when the airflow changes direction.

[0009] Preferably, the filter assembly includes a fixed clamp and a movable clamp disposed at the cut-off portion of the first connecting pipe. The fixed clamp is fixed to the inner section of the first connecting pipe, and the movable clamp is connected to the fixed clamp via threaded fasteners. A detachable pipe section, composed of two semi-circular tube segments, is clamped within the internal cavity formed by the fixed clamp and the movable clamp. Multiple grooves are formed on the inner wall of each semi-circular tube segment, and a filter screen is embedded in each groove. The pore size of the filter screen is set to a preset micron-level standard based on the diameter of the dust particles to be filtered, and gradient filtration of sulfur hexafluoride decomposition products is achieved through the series arrangement of multiple layers of filter screens.

[0010] Preferably, the device further includes an upper housing and a lower housing. The lower housing has a reinforcing rib structure on its inner bottom surface to support and secure the power supply and each electric ball valve. The upper housing and the lower housing are sealed together by a first bolt. Shock-absorbing feet, made of high-polymer elastic material, are fixedly installed at the four corners of the lower housing's bottom surface to absorb mechanical vibrations during transportation or operation. Multiple notches are provided on the side walls of the upper and lower housings, the shape of which matches the interface shape of the electric ball valves to ensure a tight pipe connection.

[0011] Preferably, the top surface of the controller is embedded in the opening of the upper housing. The controller panel is equipped with a display screen, two indicator lights, and a drain button, a sampling button, a cleaning button, and a master control button. The display screen is used to display the pressure sensor value, system operating status, and remaining power of the power bank in real time. The indicator lights include a green indicator light and a red indicator light, used to indicate normal system operation and system failure, respectively. The master control button controls the power supply of the system through a main circuit relay. The drain button, the sampling button, and the cleaning button each trigger the corresponding automated control program stored inside the controller.

[0012] Preferably, the power bank is equipped with a dedicated charging interface that passes through the side wall of the lower housing and is covered with a waterproof and dustproof cover. The output terminal of the power bank is connected to the power input terminal of the controller via a voltage regulator circuit, providing a stable DC voltage to the central processing unit and the drive control module. The voltage regulator circuit has overcurrent and overvoltage protection functions; when the current or voltage exceeds a preset safety range, it automatically cuts off the power supply to protect the controller.

[0013] Preferably, the injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve, and the vacuum electric ball valve all use low-power DC drive motors as actuators. Each electric ball valve body is equipped with sealing packing made of polytetrafluoroethylene (PTFE), which has an extremely low coefficient of friction and excellent chemical stability, ensuring airtightness even under long-term frequent switching. The opening and closing times of the electric ball valves are precisely controlled by the controller within preset time thresholds to ensure instantaneous fluid switching.

[0014] Preferably, the four-way connector has a fluid confluence chamber at its center, the volume of which is designed to be a preset minimum value to further reduce the dead volume within the system. Sealing rings are provided at the connections of the first, second, third, and fourth connecting pipes to the four-way connector. These sealing rings are made of low-temperature resistant and corrosion-resistant fluororubber material, ensuring that external air infiltration or internal sample gas leakage is prevented under different ambient temperatures.

[0015] Preferably, the purging process in step 2 specifically includes: the controller first drives the vacuum electric ball valve to open and simultaneously monitors the vacuum level of the vacuum waste gas cylinder. After confirming that the vacuum waste gas cylinder has negative pressure suction capability, the controller opens the nitrogen electric ball valve to perform preliminary flushing of the pipeline using high-pressure nitrogen for a first preset duration. Subsequently, the nitrogen electric ball valve is closed, and the sample inlet electric ball valve is opened to allow the gas to be sampled to enter the pipeline for a second preset duration. This process is repeated a preset number of cycles, and through repeated pressure fluctuations, impurity gas molecules adsorbed on the inner wall of the pipeline are stripped off and discharged.

[0016] Preferably, in the sampling process of step 3, the controller monitors the output voltage of the pressure sensor in real time. The central processing unit converts the acquired voltage signal into a pressure value and calculates the rate of change of the pressure value over time. When the absolute value of the rate of change is continuously lower than a preset stability threshold, and the current pressure value is within the preset sampling pressure range of the vacuum sampling bottle, the controller determines that the sampling has reached saturation and immediately issues a shut-off command to the injection electric ball valve and the sampling electric ball valve.

[0017] Preferably, the cleaning process in step 5 specifically includes a backflushing stage and a replacement stage. In the backflushing stage, the controller simultaneously opens the sample injection electric ball valve, the nitrogen electric ball valve, and the vacuum electric ball valve, allowing high-pressure nitrogen to enter from the second connecting pipe and split into two paths: one path passes through the first connecting pipe in reverse through the filter screen, flushing the trapped dust to the outside of the sample injection tube; the other path enters the vacuum waste gas cylinder through the fourth connecting pipe. In the replacement stage, the controller keeps the nitrogen electric ball valve normally open and periodically switches between the sampling electric ball valve and the vacuum electric ball valve, utilizing the inert nature of nitrogen to eliminate any toxic decomposition products that may remain in the pipeline.

[0018] Preferably, the connection ends of the sample inlet tube, the high-pressure nitrogen cylinder, the vacuum sampling bottle, and the vacuum waste gas cylinder are all equipped with manual shut-off valves as a secondary safety protection. Before the automated sampling program begins, the manual shut-off valve is manually confirmed to be in the open state; when the automated program ends or an emergency failure occurs, the manual shut-off valve can act as a physical barrier to manually cut off the gas path, preventing large-scale leakage of hazardous gases due to electronic component failure.

[0019] Preferably, the controller also integrates historical data storage, capable of recording pressure curves, ambient temperature, operation time, and number of cycles during each sampling process. This historical data can be exported to a host computer via the controller's external communication interface for evaluating the performance of the sampling device or performing long-term trend analysis of the electrical equipment's health status. When the stored number of samplings reaches a preset maintenance threshold, the controller displays a maintenance reminder on the screen, instructing the operator to replace the filter screen.

[0020] Preferably, the first connecting pipe is designed with a stepped mating structure, and the sealing surface at the mating point is finely ground. The inner diameters of the fixed clamp and the movable clamp are precisely matched with the outer diameter of the first connecting pipe. During the tightening process of the movable clamp, mechanical pressure is applied to ensure that the end of the pipe section is tightly fitted to the stepped sealing surface of the first connecting pipe. The mating surface of the semi-circular pipe segment is provided with a sealing gasket, and the external enveloping force of the fixed clamp and the movable clamp achieves radial and axial double sealing, ensuring that no lateral leakage occurs during high-pressure backflushing.

[0021] Preferably, the embedded software running inside the controller employs multi-threaded task management. The first thread is responsible for real-time acquisition of sensor signals and digital filtering; the second thread is responsible for running the logic state machine and controlling the logical sequence of valves; the third thread is responsible for fault diagnosis and safety interlocking, immediately forcibly closing all air intake valves and activating audible and visual alarms upon detecting abnormal pressure fluctuations or valve jamming signals. The threads communicate with each other via shared memory to ensure the response speed and reliability of the control system.

[0022] Preferably, the power bank uses a high-capacity lithium-ion battery pack, whose nominal energy density can support the device to continuously perform a preset number of complete sampling cycles. The power bank integrates a battery management system with functions such as equalization charging, over-discharge protection, short-circuit protection, and temperature monitoring. When the temperature of a single battery cell exceeds a preset safe range, the battery management system sends a shutdown signal to the controller to prevent safety risks caused by battery thermal runaway.

[0023] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention integrates multiple electric ball valves through the four-way pipe connector and combines them with an automated venting process designed with a controller, effectively eliminating interference from dead-volume gas in the pipeline. Through a preset number of replacement cycles, it ensures that the gas entering the vacuum sampling bottle originates entirely from the device being tested, greatly improving the purity of the sample and the accuracy of the analysis results, and avoiding distortion caused by the introduction of impurity gases.

[0024] 2. This invention innovatively incorporates a detachable filter assembly in the first connecting tube. The internally mounted multi-layered filter mesh effectively intercepts toxic dust generated by the high-temperature decomposition of sulfur hexafluoride at the sampling front end. This not only prevents highly toxic substances from contaminating subsequent pipelines and sampling containers, protecting the lives of testing personnel, but also reduces sample complexity through physical filtration, thus improving the accuracy of subsequent laboratory analysis.

[0025] 3. The filter assembly of this invention adopts an assembled structure of fixed and movable clamps, combined with a pipe section design composed of semi-circular tube plates, enabling rapid disassembly and assembly of the core filter components. This structure greatly simplifies the maintenance process, allowing operators to clean or replace the filter plates without disassembling the entire piping system, significantly reducing equipment operation and maintenance costs and downtime.

[0026] 4. This invention employs a controller to execute a rigorous cleaning and replacement procedure, utilizing high-pressure nitrogen to backwash and dynamically replace the pipelines. This process not only eliminates the accumulation of hazardous residual gases within the pipelines and reduces the risk of cross-contamination during continuous sampling, but more importantly, by replacing harmful gases with inert nitrogen, it fundamentally prevents the leakage of harmful gases during the recovery and relocation of the device, ensuring the safety of the work site and surrounding environment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall technical architecture of the automatic gas sampling method proposed in this invention; Figure 2 This is a schematic diagram of the core principle framework of automatic gas sampling based on multi-valve collaborative logic control in this invention; Figure 3 This is a flowchart illustrating the logical flow of the automatic emptying of dead volume in the pipeline and the sample gas circulation and replacement stage in this invention. Figure 4 This is a schematic diagram of the multi-level interaction relationship and data flow between the controller, pressure sensor, and electric ball valve in this invention; Figure 5 This is a logical flow diagram of the pipeline backflushing and hazardous residual gas replacement stage in this invention. Detailed Implementation Example

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0029] An automated gas sampling method is disclosed, whose execution logic is deeply integrated into a precisely designed mechatronics system. This system uses a controller as its core, coordinating the actions of the injection electric ball valve, nitrogen electric ball valve, sampling electric ball valve, and vacuum electric ball valve through a control command flow. To achieve efficient gas distribution and flow direction switching, the four electric ball valves are connected to a four-way connector located at the geometric center via first, second, third, and fourth connecting pipes, respectively. This cross-shaped symmetrical structure physically ensures that after gas flows in from any branch, it achieves a uniform pressure distribution within the fluid confluence chamber of the four-way connector, thereby minimizing resistance caused by local turbulence during fluid diversion.

[0030] In the aforementioned automatic gas sampling method, step 1 specifically involves system initialization and environmental preset. When the operator presses the master control button on the controller panel, the main circuit relay closes, and the chemical energy stored inside the power bank is converted into electrical energy output through the electrochemical reaction of the lithium-ion battery pack. The battery management system integrated inside the power bank immediately starts, and a high-precision voltage monitoring circuit checks the potential difference of each battery cell. If the battery management system determines that the total voltage value is higher than the preset safe operating voltage threshold, it allows electrical energy to enter the power input terminal of the controller through the voltage regulator circuit. The voltage regulator circuit utilizes the filtering characteristics of inductors and capacitors to convert fluctuating DC power into a precision DC power supply with constant frequency and voltage, powering the controller's central processing unit, storage module, signal acquisition module, and drive control module.

[0031] Within microseconds of acquiring a stable voltage, the central processing unit (CPU) executes a power-on reset command, loading preset logic control timing and safety threshold parameters from non-volatile memory. The signal acquisition module first performs analog-to-digital conversion on the current voltage of the power supply, transforming the analog level signal into digital code for transmission to the CPU. Subsequently, the CPU sends status query pulses to the sample injection electric ball valve, nitrogen electric ball valve, sampling electric ball valve, and vacuum electric ball valve via the drive control module. Each electric ball valve's internal actuator is a low-power DC drive motor, coupled with a stepper reduction mechanism. The drive control module detects the motor's feedback current to confirm that the spherical valve core inside the valve body is in the blocking position perpendicular to the airflow direction, i.e., fully closed. During this process, the controller synchronously acquires the initial electrical signal from the pressure sensor connected to the sampling electric ball valve via the signal acquisition module. This pressure sensor operates based on the piezoelectric effect, converting ambient atmospheric pressure or residual pressure in the pipeline into a millivolt-level voltage signal. The central processing unit records the voltage signal at this time as the initial zero-point reference value and stores it in random access memory for use in calculating the pressure change during subsequent sampling processes.

[0032] In the aforementioned automatic gas sampling method, step 2 specifically involves the automatic venting of dead volume gas in the pipeline. Upon detecting a level transition interrupt signal generated by the venting button, the controller immediately enters the venting control subroutine. First, the drive control module outputs a positive drive current to the motor of the vacuum electric ball valve, causing its ball core to rotate 90 degrees to the open state, thereby establishing a venting path between the four-way pipe joint and the vacuum waste gas cylinder. The vacuum waste gas cylinder has been pre-treated by an external vacuuming device before operation, maintaining an extremely low internal pressure, thus creating a significant pressure difference with the atmospheric environment.

[0033] To further enhance the evacuation effect, the controller then opens the nitrogen electric ball valve. High-purity nitrogen from the high-pressure nitrogen cylinder, driven by the pressure gradient, enters the second connecting pipe via the manual shut-off valve. As a chemically inert gas, nitrogen molecules flow at high speed within the pipe, physically detaching air, moisture, or other impurities adsorbed on the inner walls of the first, third, and four-way connectors through physical collisions. This initial flushing process lasts for a preset duration, such as 10 seconds. During this stage, the controller monitors pressure fluctuations on one side of the vacuum exhaust cylinder in real time to ensure the negative pressure suction capacity remains within its effective range.

[0034] After the initial flushing is completed, the controller closes the nitrogen electric ball valve and opens the sample injection electric ball valve for a duration of the second preset time. At this time, the sample gas to be sampled is forced into the system through the injection tube under pressure. This action aims to fill the pipeline with the actual sample gas, replacing the previous nitrogen. Subsequently, the controller switches the valve status again: closing the sample injection electric ball valve and opening the vacuum electric ball valve for suction. The above cycle of gas injection, filling, and suction is repeated three times under the logic control of the controller. Each time a cycle is executed, the central processing unit compares the pressure peak and trough values ​​collected by the pressure sensor and calculates the pressure change slope. When the consistency of the pressure characteristic curve between two consecutive cycles reaches a preset consistency threshold, it is determined that the dead volume gas in the pipeline has been completely replaced. This replacement mechanism, achieved through repeated pressure fluctuations, ensures that the gas composition entering the sampling path is highly similar to the actual gas composition of the device under test.

[0035] In the above-described automatic gas sampling method, step 3 specifically involves multi-stage filtration sampling of the sample gas. After the purging process is completed, the controller receives and responds to the trigger signal from the sampling button. At this time, the controller outputs a locking command through the drive control module to ensure that the nitrogen electric ball valve and the vacuum electric ball valve are in a fully closed locked state, preventing high-pressure nitrogen from diluting the sample or the vacuum pump from over-suctioning the sample. Subsequently, the controller synchronously sends opening commands to the sample injection electric ball valve and the sampling electric ball valve.

[0036] The gas to be sampled enters the first connecting tube through the injection tube. A core filter assembly is located at the cut-off section of the first connecting tube. This filter assembly is installed via a mechanical connection between a fixed clamp and a movable clamp. The fixed clamp is permanently sealed to one side of the first connecting tube using argon arc welding, while the movable clamp is detachably locked to the fixed clamp using a high-strength second bolt. Within the internal cavity formed by these two components is a tube segment consisting of two interlocking semi-circular tube segments. The inner walls of the semi-circular tube segments undergo electrochemical polishing, achieving a sub-micron roughness, which significantly reduces the physical adsorption of gas molecules.

[0037] Inside the pipe section, multiple grooves are arranged at equal intervals, each containing a layer of filter mesh. These filter meshes are made using porous ceramic or stainless steel powder metallurgy, with their micropore sizes designed in a gradient pattern based on the diameter distribution of the sulfur hexafluoride high-temperature decomposition dust particles to be intercepted. The first layer of filter meshes has a larger pore size to intercept coarse particles; the pore sizes of subsequent layers of filter meshes gradually decrease to achieve efficient interception of micron-sized highly toxic dust. The filtered clean gas is distributed through a four-way connector, enters the third connecting pipe, and finally flows into a pre-vacuum-evacuated vacuum sampling bottle.

[0038] During this process, the central processing unit acquires the output voltage of the pressure sensor from the signal acquisition module in real time and applies a specific digital filtering algorithm to eliminate electromagnetic interference caused by gas flow pulsation. The central processing unit continuously monitors the rate of change of the measured pressure value over time. When the pressure value rises to the preset acquisition pressure range of the vacuum sampling bottle, and the absolute value of the rate of change of pressure over time remains below the preset stability threshold, it indicates that the pressure difference inside and outside the vacuum sampling bottle has tended to balance, and the sampling process has reached saturation.

[0039] In the aforementioned automatic gas sampling method, step 4 specifically involves sampling status monitoring and safety alerts. The embedded software running inside the controller executes tasks through a multi-threaded management mode. The third thread, serving as the safety monitoring kernel, has the highest interrupt priority. During sampling, this thread continuously executes slope analysis logic. Under normal circumstances, due to the suction effect of the vacuum sampling bottle, the pressure sensor value should exhibit a smooth upward or fluctuating curve. If the central processing unit detects that the pressure data changes by less than a very small threshold within a specific time period, such as three consecutive seconds, while the absolute pressure value exceeds a preset obstruction threshold, this indicates that the airflow path is severely obstructed.

[0040] This situation is usually caused by excessive accumulation of solid decomposition products on the filter screen. Once a blockage is detected in the pipeline, the controller will immediately trigger a safety interlock: the drive control module will forcibly close the electric ball valve for sample inlet to cut off the gas supply, while simultaneously sending a trigger signal to the alarm module. The red indicator light on the controller panel will turn from off to on, emitting a continuous red warning light. At the same time, a blockage alarm message will pop up on the display screen, instructing the operator to stop operation and check the filter assembly at the first connecting pipe.

[0041] In the aforementioned automatic gas sampling method, step 5 specifically involves pipeline cleaning and hazardous residue replacement. After sampling, a thorough cleaning procedure must be performed to prevent leakage of residual toxic sample gas during device movement or storage. Upon receiving the cleaning command, the controller first opens the nitrogen electric ball valve. The high-pressure nitrogen output from the high-pressure nitrogen cylinder is split after entering the four-way connector. One stream of nitrogen flows in the opposite direction along the first connecting pipe, impacting the back of the filter screen with great kinetic energy. This reverse flushing action can peel off solid dust particles embedded in the micropores of the filter screen and blow them out of the system or to the preset dust collection area along the sample inlet tube.

[0042] The other nitrogen stream flows towards the vacuum waste gas cylinder. After the backflushing phase, the controller enters the replacement phase. At this time, the sample injection electric ball valve closes, the nitrogen electric ball valve remains open, and the controller begins to periodically alternate between the opening and closing states of the sampling electric ball valve and the vacuum electric ball valve. Each switch represents one "filling and depressurization" cycle. After the high-pressure nitrogen fills the connecting pipeline, it is then evacuated by the vacuum waste gas cylinder. Through this repeated cycle of filling and evacuation, the concentration of residual sample gas molecules in the pipeline decreases geometrically.

[0043] The replacement efficiency logic described in the text is as follows: Setting the initial sample gas concentration as a baseline, after the first replacement cycle, the residual concentration equals the initial concentration multiplied by a coefficient determined by the ratio of the pipeline dead volume to the nitrogen filling volume. After multiple consecutive cycles, the residual concentration will fall below the preset safety detection threshold. Finally, when the system determines that the residual gas has been completely converted into inert nitrogen, the controller issues a final shutdown command, closes all electric ball valves, illuminates a green indicator light to indicate the completion of the operation, and cuts off the main power supply to enter a low-power standby state.

[0044] In terms of hardware structural support, the lower housing serves as the base of the entire device, with a crisscrossing reinforcing rib structure on its internal bottom surface. These ribs significantly enhance the lower housing's ability to support heavy components such as high-pressure nitrogen cylinders and power banks by increasing the structure's cross-sectional moment of inertia. At the four corners of the lower housing's bottom surface are pads made of a high-polymer elastic material. These pads utilize the viscoelasticity of the long-chain molecules within the material to convert high-frequency mechanical vibrations from the ground into weak heat dissipation, thereby protecting the delicate electronic components inside the controller from physical impacts.

[0045] The upper and lower housings are secured together with a first bolt. To ensure airtightness when the piping exits, a fluororubber sealing strip is embedded at the edge of the notch on the side wall of the housing. Fluororubber has excellent chemical resistance and resistance to high and low temperatures, maintaining its elasticity even under long-term outdoor operating conditions, preventing external dust or moisture from entering the housing and damaging the motor of the electric ball valve. The controller is fixed to the top surface of the upper housing via a through-mount, and its display screen features an anti-glare design, ensuring that operators can clearly read pressure values ​​and system status even in bright sunlight.

[0046] The first connecting pipe features a stepped mating structure. This structure provides self-centering characteristics in mechanical assembly. When the movable clamp applies axial pressure to the fixed clamp via the second bolt, the stepped sealing surfaces press against each other, causing plastic deformation of the intermediate metal sealing gasket, thus forming a mechanical seal interface capable of withstanding high pressure. The mating surface of the semi-circular tube segment also features fine grooves to accommodate the sealing strip, ensuring that even if the nitrogen pressure exceeds the preset normal operating pressure during backflushing, no lateral gas leakage will occur.

[0047] As the power source for the entire device, the power bank utilizes a high-energy-density lithium-ion battery pack. Its integrated voltage regulator circuit features multiple protection mechanisms. When the signal acquisition module detects that the load current exceeds the preset overcurrent safety value—for example, when a motor jams causing a current surge—the fast-blowout logic within the voltage regulator circuit will cut off the power supply within milliseconds. Furthermore, the power bank's waterproof and dustproof cover effectively isolates it from corrosive gases that may be present at the sampling site, extending the lifespan of the charging port.

[0048] The internal design of the four-way pipe fitting fully embodies the principle of minimum dead volume. The shape of its fluid confluence chamber is optimized to be streamlined, eliminating internal dead zones and vortex generation points. All connection points between the pipe fitting and each connecting pipe utilize low-temperature resistant fluororubber sealing rings. This sealing material maintains good physical flexibility even in extremely cold environments down to -40 degrees Celsius, preventing gas leakage due to material embrittlement and ensuring reliable operation of the device in all weather conditions.

[0049] The controller's internal storage module not only stores the control algorithm but also provides historical data logging. Each time a sampling cycle is executed, the central processing unit writes the ambient temperature, peak pressure, number of cycles, and the estimated percentage of filter wear to a log file. When connected to a host computer via an external communication interface, this data can be exported for subsequent equipment health prediction. If the system's cumulative sampling count exceeds a preset maintenance threshold, the central processing unit will issue a mandatory maintenance reminder via the display screen during the next power-on self-test, requiring operators to disassemble, clean, or replace the filter screen, thus ensuring both sampling accuracy and operational safety in a closed-loop manner. Example

[0050] Based on the automated gas sampling method described in Example 1, this example provides an optimized technical solution for extreme high-pressure environments. In this solution, the materials of the first, second, third, and fourth connecting pipes are upgraded from ordinary corrosion-resistant metals to high-strength nickel-based alloys. This alloy has a denser crystal structure at the molecular level, enabling it to withstand greater internal pressure without creep deformation.

[0051] At the methodological level, the automatic purging logic for the dead volume of the pipeline in step 2 has been adaptively adjusted. Before performing the initial purging, the controller first acquires the ambient temperature parameters of the external environment through the signal acquisition module. Since the gas state follows specific physical laws, the central processing unit automatically adjusts the preset duration of nitrogen purging based on the ambient temperature value. When the ambient temperature is low, causing a decrease in the activity of gas molecules, the central processing unit will proportionally increase the first preset duration to ensure the replacement effect. The logic described in words is: the purging duration and the ambient temperature show a negative correlation trend, that is, for every preset temperature decrease, the purging duration increases by a preset time step.

[0052] During the sample gas sampling process in step 3, the configuration of the filtration assembly was also enhanced. In addition to the original multi-layer filter screen, an additional activated carbon adsorption layer was added at the outlet end of the detachable tube section. This adsorption layer utilizes the huge specific surface area and molecular sieve effect of activated carbon to chemically adsorb extremely small toxic molecules that may penetrate the filter screen. This provides double safety for the testing personnel. Furthermore, the pressure sensor's acquisition frequency was set to the highest level at this time to capture transient fluctuations in the high-pressure gas flow.

[0053] In step 5 of the cleaning process, a pressure maintenance detection sub-step is added. After the replacement cycle is completed, the controller closes all valves, maintaining a certain pressure of nitrogen in the pipeline, and continuously monitors the pressure sensor readings. If the pressure drop is less than a preset leakage threshold within a preset pressure maintenance time, the controller determines that the entire system is airtight and allows the system to shut down. This logic ensures that the mechanical seal structure of the equipment is not damaged after undergoing high-pressure sampling, laying the foundation for the next operation.

[0054] In this embodiment, the drive control module inside the controller employs pulse width modulation (PWM) technology to control the motor of the electric ball valve. By adjusting the duty cycle, buffering action is achieved during the valve opening and closing process. This "soft start" and "soft stop" mechanism avoids the mechanical impact on the pressure sensor and filter screen caused by the violent pressure pulse generated when the valve opens instantaneously, greatly extending the fatigue life of core precision components.

[0055] The power bank's battery management system incorporates thermal management logic. The central processing unit monitors battery temperature in real time via thermistors attached to the battery pack surface. During continuous, high-intensity sampling operations, if frequent motor starts cause the battery temperature to rise too quickly, the system automatically limits the cleaning cycle frequency. By increasing the interval between cycles, it utilizes natural convection cooling from the casing to lower the battery temperature. The logic described in the text is as follows: when the measured temperature exceeds the first safe temperature warning value, the system forcibly inserts a cooling waiting period; when the measured temperature exceeds the second dangerous temperature threshold, the system immediately cuts off all power and locks the valves.

[0056] Furthermore, in this embodiment, a polytetrafluoroethylene (PTFE) coating is added to the inner wall of the four-way connector. This coating has extremely low surface energy, making it very difficult for gas molecules to form a stable adsorption layer on its surface. This reduces the amount of residual dead volume gas at the source, allowing the preset purity standard to be achieved with fewer cycles when performing steps 2 and 5, thereby improving operational efficiency and saving nitrogen consumption. Example

[0057] This embodiment, based on Embodiment 1, extends the intelligent scheduling algorithm of the controller for multi-point continuous sampling scenarios. In this scenario, the device may need to connect different devices to be tested sequentially. To prevent cross-contamination of gases between different devices, the controller introduces device identification and sampling mode memory functions.

[0058] When performing step 1, the operator can select "Continuous Sampling Mode" via the menu on the controller panel. In this mode, the cleaning intensity of step 5 will automatically increase. The central processing unit will retrieve the pressure peak record from the previous sampling round. If the gas pressure in the previous sampling round was extremely high, it means that there are many residual molecules adsorbed on the inner wall of the pipeline, and the system will automatically increase the counter for the number of replacement cycles. The logic described in the text is: the final determined total number of replacement cycles is equal to the sum of the preset base number of cycles and a correction coefficient determined by the historical pressure peak.

[0059] In step 3, the controller dynamically assesses the status of the filter assembly. By calculating the real-time pressure drop during sampling—the difference between the pressure on the inlet tube and the pressure measured by the pressure sensor—the central processing unit can estimate the degree of filter clogging in real time. If this difference shows a significant non-linear growth trend with the increase in the number of samplings, the controller will display the remaining lifespan of the filter in real time on the screen as a progress bar. When the remaining lifespan is less than 10% of the preset value, the system will force a manual replacement operation after the next cleaning cycle; otherwise, the triggering permission of the sampling button will be locked.

[0060] To enhance the device's independence in field operations, the mobile power supply in this embodiment integrates a solar charging energy harvesting circuit. This circuit connects to an external flexible solar panel, utilizing the photovoltaic effect to replenish the lithium battery pack. The controller's battery management system calculates the balance point between charging power and system standby power consumption in real time and displays the estimated battery life on the screen.

[0061] In the safety warning logic of step 4, a linkage with the wireless communication module has been added. When the controller determines that a fault such as blockage or extremely low battery power has occurred, in addition to the local audible and visual alarm, it will also send the fault code and current geographical coordinates to the remote management backend via Low Power Wide Area Network (LPWAN) protocol. This allows maintenance personnel to monitor the operating status of sampling devices distributed in different substations in real time, enabling remote fault diagnosis.

[0062] In this embodiment, the device's housing structure utilizes a lightweight carbon fiber reinforced composite material. This material, while maintaining a specific strength comparable to nickel-based alloys, significantly reduces the overall weight of the device, greatly improving its portability. The feet are designed as height-adjustable threaded posts, allowing the device to be placed stably on uneven, rocky surfaces or inclined equipment bases.

[0063] During the replacement phase of step 5, the controller also drives the display to show the real-time pipeline purity percentage. This percentage is a theoretical value calculated using a built-in fluid replacement model based on nitrogen filling pressure, vacuum suction limit, and number of cycles. When this value reaches 99.99%, the controller will emit a clear beep, indicating that the system has reached a chemically pure state and can be safely disconnected from the device under test.

[0064] Finally, all operation commands and status feedback in this embodiment support voice synthesis output. The voice chip integrated inside the controller can convert text information such as "Draining in progress," "Sampling completed," and "Please replace filter" into clear human voice, which is then played through a waterproof speaker on the side of the lower housing. This allows operators to accurately know the working progress of the device even when wearing heavy protective clothing or in dimly lit environments, greatly improving the user-friendliness of human-machine interaction and operational safety.

[0065] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method of automatic gas sampling, characterized by, The procedure is performed using a device comprising a controller, an electric ball valve for injection, an electric ball valve for nitrogen, an electric ball valve for sampling, an electric ball valve for vacuum, and a four-way connector, and specifically includes the following steps: Step 1: System initialization and environment preset. The controller obtains power from the mobile power supply and starts up. It detects the initial closed state of the sample injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve and the vacuum electric ball valve, and simultaneously collects the initial signal of the pressure sensor connected to the sampling electric ball valve. Step 2: The dead volume gas in the pipeline is automatically vented. The controller controls the opening of the vacuum electric ball valve and the nitrogen electric ball valve to establish a venting channel. The residual gas in the pipeline is guided into the vacuum waste gas cylinder through the four-way pipe joint. Then, the opening and closing states of the sample electric ball valve and the vacuum electric ball valve are alternately switched according to the preset logic. The dynamic flushing effect of the sample gas is used to circulate and replace the dead volume gas in the pipeline until the gas composition in the pipeline and the composition of the target gas to be sampled reach the preset consistency standard. Step 3: Multi-stage filtration sampling of sample gas. While keeping the nitrogen electric ball valve and the vacuum electric ball valve closed, the injection electric ball valve and the sampling electric ball valve are opened simultaneously. The gas to be sampled enters the first connecting pipe through the injection tube and is intercepted by the filter assembly set at the cut-off point of the first connecting pipe. The filtered clean gas enters the vacuum sampling bottle through the four-way pipe joint until the pressure value monitored by the pressure sensor reaches the preset balance range. Step 4: Sampling status monitoring and safety warning. During the sampling process, the controller receives the pressure data from the pressure sensor in real time and performs slope analysis. If the pressure data does not change within a specific time and the value is greater than the preset blockage threshold, it is determined that the pipeline is blocked. The controller immediately triggers an alarm and drives the red indicator light to light up. Step 5: Pipeline cleaning and hazardous residue replacement. After sampling, the controller executes the cleaning program, opens the nitrogen electric ball valve to guide high-pressure nitrogen into the system, and back-flushes the filter component in the first connecting pipe through the four-way pipe joint, and forces the stripped impurities into the vacuum waste gas bottle. Then, high-pressure nitrogen is used to repeatedly fill and empty all connecting pipes to replace the residual sample gas with inert gas, and finally all electric ball valves are closed.

2. The method of claim 1, wherein, In step 1, the controller executes a power-on reset command through its integrated central processing unit and loads preset logic control timing and safety threshold parameters from the storage module. The signal acquisition module in the controller performs analog-to-digital conversion on the current voltage of the mobile power supply, and allows electrical energy to enter the controller through the voltage regulator circuit when it determines that the voltage is higher than the preset safe operating voltage threshold. The drive control module in the controller sends status query pulses to the sample injection electric ball valve, the nitrogen electric ball valve, the sampling electric ball valve, and the vacuum electric ball valve respectively. By detecting the feedback current of the DC drive motor inside each electric ball valve, it confirms that the spherical valve core inside the electric ball valve is in the blocking position perpendicular to the airflow direction. The controller obtains the initial voltage signal output by the pressure sensor through the signal acquisition module, and the central processing unit records the voltage signal as the initial zero-point reference value.

3. The method of claim 1, wherein, In step 2, the controller drives the ball core of the vacuum electric ball valve to rotate 90 degrees to the open state, forming an evacuation path with a pressure gradient between the four-way pipe joint and the vacuum waste gas bottle. Subsequently, the controller opens the nitrogen electric ball valve, allowing high-pressure nitrogen to physically collide and flush the inner walls of the first connecting pipe, the third connecting pipe, and the four-way pipe joint for a duration of a first preset time. After the initial flushing is completed, the controller closes the nitrogen electric ball valve and drives the sample injection electric ball valve to open, allowing the gas to be sampled to be forced into the pipeline system through the sample injection tube for a duration of a second preset time. The above-mentioned cycle process consisting of sample gas injection, filling, and suction is repeated three times under the control of the controller. In each cycle, the central processing unit compares the pressure peak and valley values ​​collected by the pressure sensor and calculates the slope of the pressure characteristic curve. When the consistency of the pressure characteristic curve between two consecutive cycles reaches the consistency standard, it is determined that the dead volume gas in the pipeline has been replaced.

4. The method of claim 1, wherein In step 3, the controller outputs a locking command through the drive control module to lock the nitrogen electric ball valve and the vacuum electric ball valve in their closed state. The first connecting pipe into which the sampled gas enters is made of corrosion-resistant metal, and its inner wall is electrochemically polished to achieve a surface roughness at the submicron level. The filter assembly inside the first connecting pipe includes a fixed clamp and a movable clamp installed by mechanical cooperation. The fixed clamp forms a permanent sealed connection with one side of the first connecting pipe, and the movable clamp is locked to the fixed clamp by bolts. In the internal cavity formed by the fixed clamp and the movable clamp, a pipe segment consisting of two semi-circular tube pieces is loaded. The inner wall of the pipe segment has multiple grooves arranged at equal intervals, and a filter screen is embedded in each groove. The filter screen is made of porous ceramic or stainless steel powder metallurgy, and the micropore diameter of each layer of filter screen is arranged in a gradient from coarse to fine to achieve step-by-step interception of dust particles of different diameters.

5. The method of claim 1, wherein, In step 4, the embedded software running inside the controller adopts a multi-threaded task management mode, in which the third thread serves as the safety monitoring kernel and is given the highest interrupt priority. During the sampling process, the third thread continuously executes the slope analysis logic, acquires the output voltage of the pressure sensor at a preset frequency through the signal acquisition module, and applies a digital filtering algorithm to eliminate electromagnetic interference caused by gas flow pulsation. The central processing unit monitors the rate of change of the measured pressure value over time in real time. If the rate of change is less than a preset minimum threshold within a continuous three-second time range, and the absolute pressure value at this time is higher than the preset blockage threshold, it is determined that the accumulation of solid decomposition products on the filter screen has caused the pipeline to be blocked. Once a blockage is determined, the controller immediately forces the sample injection electric ball valve to shut off the gas source through the drive control module, and displays a text prompt on the controller's display screen while illuminating the red indicator light.

6. The automatic gas sampling method according to claim 1, characterized in that, In step 5, the cleaning procedure includes a backflushing stage and a displacement stage. In the backflushing stage, high-pressure nitrogen enters the four-way connector and is split, with one stream of nitrogen flowing in the opposite direction to the first connecting pipe, impacting the back of the filter screen, peeling off solid particles embedded in the micropores and blowing them out of the system along the sample inlet tube. In the displacement stage, the sample inlet electric ball valve remains closed, and the nitrogen electric ball valve remains open. The controller periodically alternates between the opening and closing states of the sampling electric ball valve and the vacuum electric ball valve, forming multiple filling and decompression cycles. After each cycle, the concentration of residual sample gas molecules in the pipeline decreases geometrically according to a coefficient determined by the ratio of the pipeline dead volume to the nitrogen filling volume, until the central processing unit determines that the residual gas concentration is lower than the preset safety detection threshold. Subsequently, the controller issues a shutdown command, closes all the electric ball valves, and enters a low-power standby state.

7. The method of claim 1, wherein The device further includes an upper housing and a lower housing. The bottom surface of the lower housing is provided with a reinforcing rib structure to increase the moment of inertia of the structural section, which is used to support the electric ball valve and the mobile power supply. The bottom corner of the lower housing is equipped with pads made of polymer elastic material. The pads utilize the viscoelasticity of the long-chain molecules inside the material to convert mechanical vibration into heat dissipation. The upper housing and the lower housing are fastened together by a first bolt, and the edges of the side wall notches of the upper housing and the lower housing are embedded with fluororubber sealing strips to form an airtight structure at the pipe outlet. The controller is fixed to the top surface of the upper housing by a through-mount, and its panel is provided with a display screen with anti-glare function to display the value of the pressure sensor, the system working status, and the remaining power of the mobile power supply in real time. The cut-off position of the first connecting pipe adopts a stepped mating structure. Under the axial pressure of the movable clamp, the stepped sealing surfaces squeeze each other and the metal sealing gasket in the middle undergoes plastic deformation, thereby forming a high-pressure resistant mechanical sealing interface.

8. The method of claim 1, wherein, The portable power bank uses a high-capacity lithium-ion battery pack and integrates a circuit system with battery management logic. The circuit system monitors the battery temperature in real time through a thermistor. If the measured temperature exceeds the first safe temperature warning value during continuous operation, the central processing unit forcibly increases the interval between two cleaning actions to utilize the convection cooling of the casing. If the measured temperature exceeds the second dangerous temperature threshold, the controller immediately cuts off the power supply and locks all the electric ball valves. The voltage regulator circuit inside the portable power bank has a fast fuse logic. When the load current is detected to exceed the preset overcurrent safety value, the power supply path is cut off within milliseconds. The fluid confluence cavity of the four-way pipe joint is designed with a streamlined structure to eliminate internal vortex generation points, and the connection points between the four-way pipe joint and each connecting pipe are all sealed with low-temperature resistant fluororubber rings to ensure physical flexibility in an environment of minus forty degrees Celsius.

9. The method of claim 1, wherein, The device is constructed using a high-strength nickel-based alloy to manufacture the first, second, third, and fourth connecting pipes to withstand internal pressure under high-pressure conditions. In step 2, the central processing unit automatically adjusts the nitrogen purging time based on the collected ambient temperature parameters, ensuring a negative correlation between the purging time and the ambient temperature; that is, for every preset temperature decrease, the purging time increases by a preset time step. In step 3, an activated carbon adsorption layer is added to the outlet end of the detachable pipe section to chemically adsorb toxic molecules passing through the filter screen using the molecular sieve effect. After the replacement phase in step 5, the controller adds a pressure holding detection step, closing all valves and monitoring the pressure sensor readings. If the pressure drop within the preset holding time is less than a preset leakage threshold, the system is deemed to have good airtightness.

10. The method of claim 1, wherein The controller executes an intelligent scheduling algorithm. In step 1, it provides device identification and sampling mode selection functions through the display screen. If continuous sampling mode is selected, the controller retrieves the pressure peak record from the previous sampling round and adjusts the total number of replacement cycles in step 5 accordingly, so that the total number of replacement cycles equals the sum of the preset base number of cycles and the correction coefficient determined by the historical pressure peak. In step 3, the controller evaluates the degree of clogging of the filter by calculating the difference between the pressure on the injection tube side and the actual pressure measured by the pressure sensor, and displays the remaining life of the filter in the form of a progress bar on the display screen. When the remaining life is less than 10% of the preset limit, the controller locks the triggering permission of the sampling button and issues a maintenance reminder. The controller also integrates a voice synthesis module, which converts operation commands and status feedback into human voice signals and plays them through a waterproof speaker.

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