Fire extinguisher intelligent inspection method and system based on pressure monitoring

Abstract

The present application relates to fire extinguisher health management inspection technical field, disclose a kind of based on pressure monitoring's fire extinguisher intelligent inspection method and system, comprising: forming temperature and pressure time series data, forming temperature cycle, determine the pressure recovery state of temperature cycle, determine the temperature pressure drop coefficient of target fire extinguisher, determine the predicted pressure of target fire extinguisher at target low temperature, determine target low temperature pressure margin, form the inspection result of target fire extinguisher.Based on the above method, inspection is no longer limited to determine whether the current pressure crosses fixed boundary, can distinguish normal pressure change that can recover with temperature rebound and the sustained decline of actual pressure storage level, and whether the target fire extinguisher can maintain minimum working pressure under subsequent low temperature conditions is evaluated, solve the problem that fixed pressure threshold or single sampling time temperature compensation is difficult to reflect pressure recovery, long-term pressure change and future low temperature risk.

Description

Technical Field

[0001] This invention relates to the field of fire extinguisher health management and inspection technology, and in particular to a fire extinguisher intelligent inspection method and system based on pressure monitoring. Background Technology

[0002] Fire extinguishers, as commonly used firefighting equipment, typically store pressurized propellant gas or extinguishing medium inside. They utilize this internal pressure to spray the extinguishing agent, extinguishing initial fires. In oil extraction, oil and gas gathering and transportation, well site operations, and station equipment operation, fire extinguishers are usually distributed around wellheads, gathering and transportation stations, skid-mounted equipment areas, and other outdoor work areas. Due to the large number and wide distribution of fire extinguishers in these areas, and the fact that some areas are often unattended or require infrequent manual inspections, remote monitoring of the fire extinguisher's pressure is usually necessary to promptly detect any pressure anomalies that may affect their normal use.

[0003] Existing fire extinguisher inspection methods typically acquire fire extinguisher pressure data according to a preset sampling period and compare the pressure values ​​at each sampling time with a preset pressure range. When the pressure value is lower than the preset lower limit, the fire extinguisher is considered to be at risk of depressurization; when the pressure value is within the preset pressure range, the fire extinguisher is generally considered to be in a normal pressurization state. This type of method mainly generates inspection results based on the pressure value at the current sampling time, and the judgment process is relatively direct.

[0004] However, in areas like Daqing Oilfield where winter temperatures are low and diurnal temperature variations are significant, open-air fire extinguishers repeatedly experience environmental changes such as cooling, low-temperature maintenance, and subsequent warming. When the ambient temperature decreases, the state of the driving gas or gas phase space inside the fire extinguisher changes with the temperature, and the pressure may decrease accordingly; after the ambient temperature rises, the pressure drop caused by the temperature change usually recovers accordingly. Therefore, even if no actual pressure loss occurs, the same fire extinguisher may exhibit different pressure values ​​at different ambient temperatures, and the pressure values ​​collected during low-temperature periods cannot fully represent its stable storage pressure level.

[0005] Meanwhile, during long-term deployment and use, fire extinguishers may experience a slow pressure drop due to changes in the condition of valves, sealing connections, or other pressure-maintaining structures. In this case, pressure monitoring data may simultaneously include pressure changes that occur as ambient temperature decreases and recover upon temperature recovery, as well as pressure changes that persist after temperature recovery. Because pressure changes from different sources are reflected in the same pressure time series, it is usually difficult to determine whether the current pressure drop is mainly a normal temperature response or is also accompanied by a decrease in the actual storage pressure level of the fire extinguisher, based solely on the pressure value at a single sampling point during a low-temperature period.

[0006] To reduce the impact of ambient temperature changes on pressure assessment results, some existing inspection methods select a corresponding pressure assessment range based on the current ambient temperature, or compensate for the current pressure value based on the ambient temperature at the same sampling time. These methods can, to some extent, avoid directly classifying pressure drops at low temperatures as pressure loss, but their primary focus remains on the current temperature and pressure values. The processing results are typically used to correct the current pressure or adjust the current pressure assessment boundary.

[0007] For fire extinguishers that are dispersed across well sites, gathering stations, and skid-mounted equipment areas, relying solely on the ambient temperature and pressure values ​​at a single sampling point is insufficient to reflect whether the pressure of the fire extinguisher can recover after a period of ambient temperature change, nor is it easy to determine whether long-term pressure changes are primarily caused by ambient temperature variations. When fire extinguishers undergo multiple cooling and warming processes over a long period, the temperature compensation results at a single sampling point are also insufficient to reflect the continuous relationship between pressure changes over different time periods.

[0008] Furthermore, the current pressure value, after temperature compensation, falls within the preset pressure range. This only indicates that the fire extinguisher is not below the corresponding pressure boundary at the current temperature and sampling time; it does not directly reflect its pressure margin under subsequent lower temperature conditions. As the ambient temperature continues to decrease, the pressure drop caused by temperature changes will further compress the fire extinguisher's remaining margin relative to the minimum operating pressure. When the fire extinguisher experiences a continuous actual pressure drop, the aforementioned factors may collectively affect its pressure storage state under subsequent low-temperature conditions. Summary of the Invention

[0009] Based on this, in a first aspect, the present invention provides a method for intelligent inspection of fire extinguishers based on pressure monitoring, comprising: The pressure monitoring data and corresponding ambient temperature data of the target fire extinguisher are acquired to form temperature-pressure time series data. From this data, stable temperature-pressure segments, representative temperature values, representative pressure values, and representative times for each stable segment are determined. Based on the representative temperature values ​​and representative times of each stable temperature-pressure segment, the preceding and following temperature comparison segments before and after the ambient temperature deviation are determined. A low-temperature stable segment is then identified between these segments, forming a temperature cycle. The pressure difference between the preceding and following temperature comparison segments is determined based on their representative pressure values, and the pressure recovery state of the temperature cycle is determined accordingly. Based on the temperature and pressure changes corresponding to the preceding, following, and low-temperature stable segments in the temperature cycle where the pressure recovery state is normal, the temperature-pressure drop coefficient of the target fire extinguisher is determined. Using the temperature-pressure drop coefficient, the representative pressure values ​​of each stable temperature-pressure segment are converted to reference temperature-converted pressures at a preset reference temperature. The rate of pressure drop and the final reference temperature-converted pressure of the target fire extinguisher are determined based on the changes in these reference temperature-converted pressures with representative times. Based on the terminal reference temperature converted to pressure, temperature pressure drop coefficient, storage pressure drop rate, predicted target low temperature and its corresponding time, the predicted pressure of the target fire extinguisher at the target low temperature is determined, and the target low temperature pressure margin is determined based on the predicted pressure and the minimum operating pressure of the target fire extinguisher. The inspection results of the target fire extinguisher are then generated based on the pressure recovery status, storage pressure drop rate, and target low temperature pressure margin of each temperature cycle.

[0010] Secondly, a fire extinguisher intelligent inspection system based on pressure monitoring is provided, the system comprising: The temperature and pressure data processing module acquires pressure monitoring data and corresponding ambient temperature data from the target fire extinguisher, forming temperature and pressure time-series data. It then determines each stable temperature and pressure segment, along with representative temperature, pressure, and time values ​​for each segment. The temperature cycle formation module, based on the representative temperature and time values ​​of each stable temperature and pressure segment, identifies the preceding and following temperature comparison segments before and after an ambient temperature deviation. It also identifies a low-temperature stable segment between these segments, forming a temperature cycle. The pressure recovery state determination module determines the same-temperature pressure difference based on the representative pressure values ​​of the preceding and following comparison segments, and then determines the pressure recovery state of the temperature cycle based on this pressure difference. The temperature and pressure drop coefficient determination module determines the temperature and pressure drop coefficient of the target fire extinguisher based on the temperature and pressure changes corresponding to the preceding, following, and low-temperature stable segments within the temperature cycle where the pressure recovery state is normal. The pressure change determination module converts the representative pressure values ​​of each stable temperature and pressure range into reference temperature-converted pressures at a preset reference temperature based on the temperature-pressure drop coefficient. It then determines the pressure drop rate of the target fire extinguisher and the terminal reference temperature-converted pressure based on the changes in the reference temperature-converted pressures over representative times. The low-temperature pressure prediction module determines the predicted pressure of the target fire extinguisher at the target low temperature based on the terminal reference temperature-converted pressure, temperature-pressure drop coefficient, pressure drop rate, predicted target low temperature, and its corresponding time. It also determines the target low-temperature pressure margin based on the predicted pressure and the target fire extinguisher's minimum operating pressure. The inspection result generation module generates inspection results for the target fire extinguisher based on the pressure recovery status, pressure drop rate, and target low-temperature pressure margin of each temperature cycle.

[0011] The beneficial effects achieved by the provided technical solution include at least the following: (1) This invention utilizes the temperature and pressure monitoring data of the target fire extinguisher to combine the pressure recovery after the change in ambient temperature, the long-term storage pressure change trend after the elimination of temperature influence, and the pressure margin under subsequent low temperature conditions to form the inspection results. This makes the inspection no longer limited to judging whether the current pressure has exceeded the fixed boundary. It can distinguish between normal pressure changes that can recover with the temperature rise and the continuous decline of the actual storage pressure level. It can also make a targeted assessment of whether the target fire extinguisher can maintain the minimum working pressure under subsequent low temperature conditions, thus solving the problem that fixed pressure thresholds or temperature compensation at a single sampling time cannot reflect the pressure recovery, long-term storage pressure changes, and future low temperature risks.

[0012] (2) By forming a temperature cycle consisting of a pre-temperature comparison section, a low-temperature stabilization section, and a post-temperature comparison section, and by using the pressure recovery allowable error considering the residual temperature difference before and after to judge the same-temperature pressure difference, the pressure recovery state is established on the basis of pressure comparison after the ambient temperature drops and returns to approximately the same temperature level. This can reduce the influence of residual temperature difference and normal measurement fluctuations on the judgment result, avoid misjudging the recoverable pressure drop caused by low temperature as an abnormal storage pressure, and identify the pressure drop that is still retained after the temperature recovery when the pressure has not yet fallen below the fixed pressure lower limit. For abnormal rising states, abnormal marking and trend data isolation can also avoid pressure detection abnormalities interfering with the determination of the subsequent storage pressure drop trend.

[0013] (3) By using the temperature cycle of the normal recovery state to determine the temperature pressure drop coefficient of the target fire extinguisher itself, the pressure representative values ​​under different ambient temperatures are uniformly converted to the preset reference temperature and the rate of pressure drop is determined. Then, the target low temperature pressure margin is calculated by combining the predicted target low temperature and its corresponding time. This can weaken the periodic impact caused by the fluctuation of ambient temperature from the long-term pressure change, quantify the degree of the actual storage pressure level continuously decreasing over time, and simultaneously include the temperature-induced pressure drop and the storage pressure drop during the prediction period in the low temperature pressure prediction, thereby identifying the risk that the current pressure is still in the normal range but the pressure margin is insufficient under subsequent low temperature conditions. Attached Figure Description

[0014] Figure 1 A flowchart of a fire extinguisher intelligent inspection method based on pressure monitoring; Figure 2 A three-stage temperature-pressure relationship diagram representing a typical temperature cycle; Figure 3 This is a graph showing the relationship between the pressure difference at the same temperature and the allowable error of pressure recovery. Figure 4 This is a graph showing the relationship between representative pressure values ​​in the same temperature comparison section before and after the test. Figure 5 This is a framework diagram of an intelligent fire extinguisher inspection system based on pressure monitoring. Detailed Implementation

[0015] Example 1: This example provides a pressure monitoring-based intelligent inspection method for fire extinguishers, executed by an inspection processing terminal. It is applicable to pressurized fire extinguishers whose internal pressure exhibits recoverable response characteristics to changes in ambient temperature. The inspection processing terminal is a server, edge gateway, or management terminal with a processor and memory. It receives pressure monitoring data, corresponding ambient temperature data, status change records, and predicted ambient temperature sequences from the target fire extinguisher, and executes the data processing steps described in this example.

[0016] like Figure 1The diagram shows a flowchart of an intelligent inspection method for fire extinguishers based on pressure monitoring. Specifically, it includes: reading status change records based on the target fire extinguisher's identification. These records include at least the fire extinguisher identification, event type, event completion status, and event completion time. Refilling, depressurization, and valve or seal repair are identified as events changing the pressure storage state; pressure sensor replacement, recalibration, zero-point correction, or acquisition channel replacement are identified as events changing the pressure detection benchmark; and moving the target fire extinguisher to a different temperature control zone or changing the location of a nearby heat source, with the change lasting for the required environmental confirmation time, is identified as an event changing the installation environment. Only completed events with a completion time are retained. When the same process includes multiple operations, the event completion time is the moment the last operation is completed and the pressure and temperature acquisition channels return to normal acquisition. For each pressure value, the ambient temperature value with the smallest time difference among the sampling time values ​​(not exceeding the allowable time deviation) is selected for association; if the time differences are the same, the earlier sampling time is selected; if no matching ambient temperature value exists, no corresponding temperature and pressure data point is generated.

[0017] The allowable time deviation is preset based on the synchronous sampling data of the pressure acquisition channel and the ambient temperature acquisition channel. It is calculated by summing the 95th percentile of the absolute value of the sampling time difference with the larger of the timestamp resolutions of the two channels, ensuring the resulting value is no greater than half the larger of the nominal sampling periods of the two channels. In this embodiment, both the percentile and quartile values ​​are determined using the nearest rank method. When calibration data is insufficient, existing valid parameters matching the target fire extinguisher and its sensor configuration are used; if no existing valid parameters exist, the corresponding parameters are determined as unavailable.

[0018] Filter status change events whose completion time is no later than the current inspection time, and determine the latest status change event as the most recent status change event, and set its completion time as the current data start time; if no status change event exists, determine the sampling time of the first temperature and pressure data point as the current data start time. Retain temperature and pressure data points whose sampling time falls between the current data start time and the current inspection time, and sort them by sampling time to form temperature and pressure time series data. Use the median interval between adjacent pressure sampling times during normal acquisition as the actual sampling period. Divide the shortest stable duration by the actual sampling period plus one, and the larger of the two values ​​is determined as the minimum number of data points; if the number of temperature and pressure data points is less than the minimum number of data points, the temperature and pressure time series data status is determined as insufficient data, the formation of stable temperature and pressure segments is stopped, and the current number of data points, the minimum number of data points, and the current data start time are recorded. The inspection result is determined by the final result formation step.

[0019] The temperature and pressure data points are arranged according to the sampling time, and temperature and pressure data points with an interval of no more than the allowable sampling interval between adjacent sampling times are grouped into the same continuous data segment. The allowable sampling interval is determined based on the 99th percentile of the time interval between adjacent temperature and pressure data points during normal acquisition and the nominal sampling period, and shall not exceed three times the nominal sampling period.

[0020] For each continuous data segment, a candidate data interval search is performed. The first temperature and pressure data point of the continuous data segment is determined as the starting point of the current interval, and the endpoint of the current interval is moved sequentially according to the sampling time. For each added temperature and pressure data point, the difference between the maximum and minimum ambient temperature values ​​within the current interval is calculated. When the difference exceeds the temperature stability threshold, the starting point of the current interval is moved sequentially from earliest to latest sampling time, and the difference between the maximum and minimum ambient temperature values ​​is recalculated after each move, until the difference is no greater than the temperature stability threshold or the current interval is empty. When the temperature fluctuation range of the current interval is no greater than the temperature stability threshold, and the duration between the endpoint and the starting point of the interval reaches the sum of the thermal response waiting time and the shortest stable duration, the current interval is determined as a candidate data interval, and the search continues until the position where the temperature stability condition is no longer met after adding the next temperature and pressure data point is added. The maximum interval before the expansion stops is then taken as the candidate data interval. After a candidate data interval is formed, the search for the next candidate data interval continues from the first temperature and pressure data point after that candidate data interval.

[0021] The temperature stability threshold is preset during the calibration phase when the ambient temperature is stable. A calibration data range with a minimum preset calibration quantity and a duration not shorter than the shortest stabilization time is obtained. The difference between the maximum and minimum ambient temperature values ​​in each range is calculated, and the larger of the 95th percentile of each difference and the two smallest resolution units of the temperature sensor is taken as the temperature stability threshold.

[0022] After setting the pressure stabilization threshold, temperature response calibration is performed on the target fire extinguisher model. Under the condition of constant storage pressure, the ambient temperature is changed from the first stable temperature level to the second stable temperature level and maintained. Timing begins when the ambient temperature enters the range of the next temperature stabilization threshold above and below the second stable temperature level. When the difference between the maximum and minimum pressure values ​​within a consecutive shortest stabilization period is not greater than the pressure stabilization threshold, the median of the pressure values ​​within that consecutive period is determined as the final stable pressure value, and timing stops at the end of that consecutive period. The 95th percentile value of the timing duration, which is no less than the preset minimum number of calibrations, is taken as the thermal response waiting time.

[0023] The shortest stability time is preset based on the nominal sampling period and the minimum number of data points required for stability determination. The minimum number of data points for stability determination is preset to an integer not less than five, and the minimum number of data points minus one is multiplied by the nominal sampling period to obtain the shortest stability time. When the nominal sampling period changes, the shortest stability time is re-determined based on the updated nominal sampling period.

[0024] For any candidate data interval, the start time of the interval is added to the thermal response waiting time to obtain the end time of the waiting period. Temperature and pressure data points whose sampling time is earlier than the end time of the waiting period are deleted. For the retained data, the difference between the last sampling time and the first sampling time is taken as the duration, and the difference between the maximum pressure value and the minimum pressure value is taken as the pressure fluctuation range. When the duration is not less than the shortest stable duration and the pressure fluctuation range is not greater than the pressure stability threshold, the retained data is determined as the stable temperature and pressure range.

[0025] During the calibration phase, when both the storage pressure and ambient temperature are stable, a data range is obtained that is no less than the preset minimum calibration quantity and lasts for no less than the shortest stabilization time. The difference between the maximum and minimum pressure values ​​within each range is calculated, and the larger of the 95th percentile of each difference and the two smallest resolution units of the pressure sensor is taken as the calibration pressure stabilization threshold. If the calibration pressure stabilization threshold is no greater than 2% of the pressure sensor's full scale, it is used as the pressure stabilization threshold; if it exceeds 2%, the calibration is marked as abnormal, and the existing effective pressure stabilization threshold in the parameter table continues to be used; if no existing effective pressure stabilization threshold exists, the pressure stabilization parameter status is determined to be unavailable, and the identification of the stable temperature and pressure range is stopped.

[0026] All ambient temperature and pressure values ​​within the stable temperature and pressure range were extracted separately. For ambient temperature values, they were sorted from smallest to largest. When the number of ambient temperature values ​​was odd, the middle value after sorting was determined as the representative temperature value. When the number of ambient temperature values ​​was even, the sum of the two middle values ​​after sorting was divided by two, and the result was determined as the representative temperature value. The pressure representative value was calculated using the same method, based on the sorted pressure values. The end time of the stable temperature and pressure range was determined by the sampling time of the last temperature and pressure data point within that range.

[0027] Stable temperature and pressure segments are retrieved from earliest to latest according to representative time, and temperature cycles are formed using a non-overlapping cyclic interval method. The current stable temperature and pressure segment is used as a candidate preceding same-temperature comparison segment, and candidate following same-temperature comparison segments are retrieved from nearest to farthest. After a temperature cycle is formed, the following same-temperature comparison segment is used as the next candidate preceding same-temperature comparison segment. If the current candidate preceding same-temperature comparison segment cannot form a temperature cycle with the subsequent stable temperature and pressure segment, the next stable temperature and pressure segment is used as the new candidate preceding same-temperature comparison segment to continue the search. Adjacent temperature cycles can share a single stable temperature and pressure segment that connects their beginning and end, but their internal time intervals must not overlap.

[0028] Using the representative time of each stable temperature and pressure segment as the sorting field, all stable temperature and pressure segments are arranged from earliest to latest according to their representative time. If two stable temperature and pressure segments have the same representative time, they are arranged from earliest to latest according to their start time; if the start times are still the same, they are arranged according to their original order in the temperature and pressure time series data. After sorting, each stable temperature and pressure segment is assigned an incrementally increasing order position, ensuring that a stable temperature and pressure segment in a previous order position is necessarily earlier than a stable temperature and pressure segment in a subsequent order position. All subsequent judgments regarding before, after, and between the two are based on this sorting result, not on the magnitude of the representative temperature value. This establishes a unique time order, providing a clear temporal basis for identifying the stable state before and after a temperature drop.

[0029] First, select the stable temperature and pressure segment that appears first in the ranking. Then, starting from the position at least one stable temperature and pressure segment away, search for the stable temperature and pressure segments that follow it in order of representative time from earliest to latest. Let the representative temperature value of the preceding stable temperature and pressure segment be the representative temperature value of the preceding segment, and the representative temperature value of the following stable temperature and pressure segment be the representative temperature value of the following segment. Subtract the representative temperature value of the preceding segment from the representative temperature value of the following segment, and take the absolute value of the difference to obtain the same-temperature difference value. When the same-temperature difference value is less than or equal to the allowable deviation of the same temperature, and the difference in the ranking positions of the two stable temperature and pressure segments is not less than two, it indicates that their temperature levels are close and there is an intermediate stable temperature and pressure segment between them that can be used to judge temperature deviation. Therefore, they are determined as candidate preceding same-temperature comparison segments and candidate following same-temperature comparison segments, respectively. When the same-temperature difference value is greater than the allowable deviation of the same temperature, they cannot be used as same-temperature comparison segments, but the search for subsequent stable temperature and pressure segments continues.

[0030] During the calibration phase when the ambient temperature is maintained at the same stable level, the absolute value of the difference between the representative temperature values ​​of adjacent stable temperature and pressure ranges, which is no less than the preset minimum number of calibration values, is calculated. The larger of the 95th percentile of each absolute value and the two smallest resolution units of the temperature sensor is taken as the allowable deviation at the same temperature. The allowable deviation at the same temperature is less than the effective temperature drop threshold.

[0031] Read the representative temperature values ​​of each stable temperature and pressure segment between the pre-candidate and post-candidate temperature comparison segments. First, divide each representative temperature value by the minimum resolution unit of the temperature sensor, round the quotient to the nearest integer, and then multiply it by the minimum resolution unit to obtain the quantized representative temperature value. Determine the lowest quantized representative temperature value from among the quantized representative temperature values ​​and record the corresponding stable temperature and pressure segment and its representative time. Subsequent selections for equal lowest temperatures and low-temperature stable segments will be based on the quantized representative temperature value.

[0032] The representative temperature values ​​of the candidate preceding and following isothermal comparison segments are compared, and the smaller value is determined as the lower limit of the isothermal baseline. Then, the effective temperature drop is obtained by subtracting the lowest representative temperature value from the lower limit of the isothermal baseline. When the effective temperature drop is greater than or equal to the effective temperature drop threshold, it indicates that a temperature drop reaching a preset magnitude has occurred between the candidate preceding and following isothermal comparison segments; the candidate preceding isothermal comparison segment is then designated as the preceding isothermal comparison segment, and the candidate following isothermal comparison segment as the following isothermal comparison segment. When the effective temperature drop is less than the effective temperature drop threshold, it indicates that the intermediate temperature change is insufficient to constitute an effective temperature cycle, and the search continues for candidate following isothermal comparison segments located further down the spectrum.

[0033] During the calibration period when the ambient temperature fluctuates naturally without active temperature adjustment, calculate the absolute value of the temperature representative value change of no less than the preset minimum number of adjacent stable temperature and pressure ranges, and take the maximum value among the 99th percentile, the sum of the temperature stability threshold and the allowable deviation at the same temperature, and twice the allowable deviation at the same temperature as the effective temperature drop threshold.

[0034] If there is only one stable temperature and pressure segment with the lowest quantized temperature representative value between the previous and subsequent isothermal comparison segments, then that stable temperature and pressure segment is determined as the low-temperature stable segment; if there are multiple stable temperature and pressure segments, then the stable temperature and pressure segment with the earliest representative time is determined as the low-temperature stable segment.

[0035] The preceding isothermal comparison segment, the low-temperature stability segment, and the subsequent isothermal comparison segment are correlated from earliest to latest according to their representative times, forming a temperature cycle record. The temperature cycle record at least saves the representative temperature, representative pressure, and representative time for the preceding isothermal comparison segment, the low-temperature stability segment, and the subsequent isothermal comparison segment. Since the subsequent isothermal comparison segment represents the return of the ambient temperature to approximately the same level as the preceding isothermal comparison segment after a decrease, the representative time of the subsequent isothermal comparison segment is determined as the representative time of the temperature cycle, used to indicate the time when the temperature cycle has been completed.

[0036] like Figure 2The figure shows a three-stage temperature-pressure relationship diagram for a representative temperature cycle. The horizontal axis represents the representative temperature value, and the vertical axis represents the representative pressure value. Each data set consists of three data points corresponding to the preceding temperature comparison segment, the low-temperature stable segment, and the subsequent temperature comparison segment. The data point with the lower temperature corresponds to the low-temperature stable segment, while the two data points at higher and approximately the same temperature correspond to the preceding and subsequent temperature comparison segments, respectively. The lines connecting the data points indicate that the three stable temperature-pressure segments belong to the same temperature cycle. This figure shows representative temperature cycles for the non-recovery state, the abnormal rise state, and the normal recovery state. In the non-recovery state, the representative pressure value of the subsequent temperature comparison segment is lower than that of the preceding temperature comparison segment, and the difference exceeds the allowable error for pressure recovery. In the abnormal rise state, the representative pressure value of the subsequent temperature comparison segment is higher than that of the preceding temperature comparison segment, and its change exceeds the negative pressure recovery boundary. In the normal recovery state, the difference between the representative pressure values ​​of the preceding and subsequent temperature comparison segments does not exceed the allowable error for pressure recovery.

[0037] Both the allowable error for basic pressure recovery and the upper limit for the temperature-pressure drop ratio are non-negative. The allowable error for basic pressure recovery, the allowable pressure change for residual temperature difference, the allowable error for pressure recovery, and all representative pressure values ​​use the same pressure unit. The upper limit for the temperature-pressure drop ratio is expressed in pressure units per temperature unit, and all temperature values ​​use the same temperature unit.

[0038] Based on the target fire extinguisher's model, extinguishing agent type, rated filling state, pressure detection component model, and pressure detection range, read the allowable error for basic pressure recovery and the upper limit of the temperature-pressure drop ratio corresponding to the target fire extinguisher. The allowable error for basic pressure recovery covers the difference in representative pressure values ​​caused by pressure sensor resolution, repeated measurement fluctuations, data quantization errors, and normal pressure fluctuations within the stable temperature-pressure range, when the ambient temperatures before and after are exactly the same or the remaining temperature difference is negligible. The upper limit of the temperature-pressure drop ratio represents the maximum allowable difference in representative pressure values ​​per unit temperature difference, provided that the target fire extinguisher's pressure storage state does not undergo substantial change.

[0039] The allowable error for basic pressure recovery is preset through the isothermal stable pressure calibration process. Under the condition that the target fire extinguisher's pressure remains constant and the ambient temperature is stable, stable temperature and pressure segments are formed according to representative times, reaching the preset minimum number of calibration steps. Only for combinations of stable temperature and pressure segments with adjacent representative times and an absolute value of the difference between the representative temperature values ​​not exceeding the minimum resolution unit of the temperature sensor, the absolute value of the difference between the representative pressure values ​​of the preceding and following stable temperature and pressure segments is calculated to obtain the isothermal pressure repeatability difference. The 95th percentile value of each isothermal pressure repeatability difference is determined according to a unified quantile calculation method, and this 95th percentile value is compared with twice the minimum resolution unit of the pressure sensor; the larger of the two values ​​is taken as the allowable error for basic pressure recovery.

[0040] The upper limit of the temperature-pressure drop ratio is preset during the temperature response calibration process when the target fire extinguisher's pressure remains constant. Specifically, the target fire extinguisher is subjected to multiple different and stable ambient temperature levels. At each ambient temperature level, the thermal response waiting time is observed, and the corresponding representative temperature and pressure values ​​are obtained according to the aforementioned method for determining stable temperature and pressure ranges. For any stable temperature and pressure range where the absolute value of the difference between any two representative temperature values ​​is not less than twice the allowable deviation for the same temperature, the absolute value of the difference between their pressure and temperature values ​​is divided by the absolute value of the difference between their temperature values ​​to obtain the corresponding temperature-pressure drop ratio. The difference between these two representative temperature values ​​must not be zero. Selecting data where the difference between the representative temperature values ​​is not less than twice the allowable deviation for the same temperature avoids amplifying the temperature measurement error due to division when the temperature difference is too small. The obtained temperature-pressure drop ratios are sorted from smallest to largest, and their 95th percentile value is determined as the upper limit of the temperature-pressure drop ratio. If the target fire extinguisher's model, extinguishing agent type, rated filling state, or pressure detection benchmark changes, the upper limit of the temperature-pressure drop ratio is reset.

[0041] After obtaining the above two parameters, subtract the representative temperature value of the subsequent temperature comparison segment from the representative temperature value of the previous temperature comparison segment, and take the absolute value of the difference to obtain the remaining temperature difference between the two segments. Multiplying the upper limit of the temperature-pressure drop ratio by the remaining temperature difference before and after the temperature drop gives the allowable pressure change due to the remaining temperature difference. ,in, This represents the upper limit of the temperature-pressure drop ratio. The allowable pressure recovery error for this temperature cycle is obtained by adding the allowable error for basic pressure recovery to the allowable pressure change due to the remaining temperature difference. Since the absolute value of the difference between the representative temperature values ​​of the first and second isothermal comparison sections is no greater than the allowable deviation for isothermal conditions, the allowable error for pressure recovery has the following upper limit relationship: ,in, The allowable deviation for the same temperature is defined as the residual temperature difference. Therefore, the correction amount for the pressure recovery allowable error based on the residual temperature difference is limited by the allowable deviation for the same temperature and will not increase indefinitely with the temperature difference. If the residual temperature difference exceeds the allowable deviation for the same temperature, the corresponding two stable temperature and pressure segments are not designated as the preceding and following same-temperature comparison segments, nor is the pressure recovery allowable error calculated based on them.

[0042] Read the representative pressure values ​​of the preceding and following temperature comparison sections, and subtract the representative pressure value of the following temperature comparison section from the representative pressure value of the preceding section. Take the absolute value of the pressure difference at the same temperature, and compare the obtained absolute value with the allowable error of pressure recovery for this temperature cycle. When the condition is met... When the temperature cycle's pressure recovery state is recorded as the normal recovery state, this state indicates that after the target fire extinguisher's temperature drops and returns to approximately the same ambient temperature, the difference between the representative pressure values ​​before and after the cycle does not exceed the allowable range determined by the base pressure fluctuation and the residual temperature difference before and after the cycle. When the pressure difference at the same temperature is positive, it is compared with the allowable error for pressure recovery. When the following conditions are met: When the pressure recovery state of the temperature cycle is defined as the unrecovered state, the unrecovered state is recorded, and the isothermal pressure difference, pressure recovery allowable error, pressure exceeding the allowable error, and the representative time of the corresponding temperature cycle are saved. The pressure exceeding the allowable error is calculated by subtracting the pressure recovery allowable error from the isothermal pressure difference. The negative pressure recovery boundary is obtained by calculating the negative of the pressure recovery allowable error. Compare the isothermal pressure difference with the negative pressure recovery boundary, and when the following conditions are met: When the pressure recovery state of the temperature cycle is determined to be an abnormal rise state.

[0043] like Figure 3 The figure shows the relationship between isothermal pressure difference and pressure recovery tolerance. The horizontal axis represents the pressure recovery tolerance for each temperature cycle, and the vertical axis represents the isothermal pressure difference. The two dashed lines represent the positive and negative pressure recovery boundaries corresponding to the pressure recovery tolerance, respectively. The bilateral tolerances in the legend refer to these positive and negative pressure recovery boundaries. When the data point is between the two dashed lines, the absolute value of the isothermal pressure difference is not greater than the pressure recovery tolerance, corresponding to a normal recovery state. When the data point is above the positive pressure recovery boundary, the isothermal pressure difference is greater than the pressure recovery tolerance, corresponding to a declining, unrecovered state. When the data point is below the negative pressure recovery boundary, the isothermal pressure difference is less than the negative of the pressure recovery tolerance, corresponding to an abnormally rising state.

[0044] When the temperature cycle shows an abnormal rise, the pressure monitoring anomaly flag is set to valid, and the representative time of the temperature cycle, the representative time of the preceding and following temperature comparison segments, the pressure difference at the same temperature, and the allowable error for pressure recovery are recorded. The pressure monitoring anomaly flag remains valid until the review is completed. If the review confirms that the pressure detection component has been replaced, recalibrated, zero-point calibrated, or the pressure acquisition channel has been replaced, the corresponding event is written into the status change record and the current data start time is redefined. If the review confirms that the problem is caused by a data parsing error or a time correlation error, the corresponding data is marked as invalid, and the inspection is re-executed.

[0045] The representative moment of the subsequent isotemperature comparison segment of an abnormal temperature rise cycle is determined as the data isolation moment. Data before the representative moment of the preceding isotemperature comparison segment of the same abnormal temperature rise cycle is not used together with data after the data isolation moment for the same trend fitting. When multiple data isolation moments exist, the current storage pressure drop rate is determined only using stable temperature and pressure segments after the last data isolation moment, where the representative temperature value is within the calibrated temperature range and the number reaches the minimum preset number for trend fitting. If the number is insufficient, the storage pressure drop rate status is determined as unavailable and the reason for insufficient data is recorded.

[0046] Temperature cycles that achieve normal pressure recovery or fail to recover are defined as valid temperature cycles. These valid temperature cycles are arranged from earliest to latest according to their representative times, and the pressure recovery state of the cycle with the latest representative time is determined as the latest pressure recovery state. When representative times are the same, the valid temperature cycle that appears later in the comparison segment is selected. Temperature cycles exhibiting abnormal increases are not used to determine the latest pressure recovery state.

[0047] like Figure 4 The diagram shows the relationship between representative pressure values ​​in the preceding and following isothermal comparison segments. The preceding isothermal pressure refers to the representative pressure value in the preceding isothermal comparison segment, and the following isothermal pressure refers to the representative pressure value in the following isothermal comparison segment. The dashed line indicates that the representative pressure values ​​in the preceding and following isothermal comparison segments are equal. When the data point is near the dashed line and the difference between the preceding and following representative pressure values ​​does not exceed the corresponding allowable pressure recovery error, the temperature cycle corresponds to a normal recovery state. When the data point is below the dashed line and the difference between the preceding and following isothermal comparison segment's representative pressure value exceeds the allowable pressure recovery error, the temperature cycle corresponds to a declining, unrecovered state. When the data point is above the dashed line and the increase in the following isothermal comparison segment's representative pressure value relative to the preceding isothermal comparison segment exceeds the allowable pressure recovery error, the temperature cycle corresponds to an abnormal rise state.

[0048] It should be noted that the dashed line in this figure only indicates that the pressure values ​​before and after are equal, and does not directly represent the complete boundary of the normal recovery state. Whether a condition is considered to be in a normal recovery state should still be determined based on the allowable pressure recovery error corresponding to each temperature cycle, and not on whether the data point is visually close to the dashed line.

[0049] When no valid temperature cycle exists in the current temperature and pressure time series data, the latest pressure recovery status is determined to be unusable. If no temperature cycle exists, the reason for unusability is recorded as a missing temperature cycle; if only a temperature cycle with an abnormal upward trend exists, the reason for unusability is recorded as a pressure monitoring anomaly. The final result generation step forms a unique inspection result based on the latest pressure recovery status, pressure monitoring anomaly flags, and the usability status of other intermediate results.

[0050] Before calculating the temperature-pressure drop coefficient of the target fire extinguisher, read the reasonable range of temperature-pressure drop ratios, the calibrated temperature range, and the minimum sample size for the temperature-pressure drop coefficient corresponding to the target fire extinguisher's model, extinguishing agent type, rated filling state, and pressure measurement range. These parameters are preset separately for each fire extinguisher model; parameters corresponding to different extinguishing agent types, pressure ratings, or pressure measurement ranges are not directly mixed.

[0051] The temperature-pressure drop ratio is used to represent the pressure drop corresponding to one unit decrease in ambient temperature when the target fire extinguisher is in normal storage pressure. Its unit is pressure units per temperature unit. The reasonable range for the temperature-pressure drop ratio is one that allows it to fall within the closed interval for calculating the temperature-pressure drop coefficient, denoted as: ,in, This represents the lower limit of the reasonable range for the temperature-pressure drop ratio. The upper limit of the reasonable range for the temperature-pressure drop ratio is defined, and it satisfies the following: The reasonable range of the temperature-pressure drop ratio is preset using temperature response calibration data from normal fire extinguishers of the same model before the target model fire extinguisher is put into service for inspection. Specifically, using the reference temperature-pressure drop ratio formed by normal fire extinguishers of the same model under the conditions of constant storage pressure and pressure detection benchmark, after deleting values ​​not greater than zero, the remaining reference temperature-pressure drop ratios are arranged in ascending order of value, and the first and third quartiles are determined respectively. The difference between the two is calculated to obtain the interquartile range. The lower and upper limits of the reasonable range of the temperature-pressure drop ratio are determined as follows: , ,in, It is the first quartile. It is the third quartile. When a pressure sensor or temperature sensor is replaced, recalibrated, or its range changes, the appropriate range for the temperature-pressure drop ratio should be redefined.

[0052] The calibration temperature range is a closed range of ambient temperatures that allows for the formation of the temperature-pressure drop ratio and is used for pressure storage trend calculations; it is denoted as: ,in, This is the lower limit of the calibration temperature range. This is the upper limit of the calibration temperature range. The calibration temperature range is determined jointly based on the applicable temperature range of the target fire extinguisher, the effective measurement range of the temperature sensor, and the actual temperature range covered during the temperature response calibration process. Let the applicable temperature range of the target fire extinguisher be... The effective measurement range of the temperature sensor is The actual temperature range covered by the temperature response calibration process is: ,but: , Only when The resulting calibrated temperature range is valid. By using the intersection of three temperature ranges, it can be ensured that the temperature data involved in the calculation is within both the allowable operating temperature range of the target fire extinguisher and the temperature range where the temperature sensor and temperature pressure drop coefficient have been verified.

[0053] The number of candidate samples was verified using the effective temperature-pressure drop ratio of normal fire extinguishers of the same model. The number of candidate samples was an odd number of not less than five. For each number of candidate samples, multiple consecutive verification windows were formed according to the representative time of the temperature cycle. For each verification window, the median of all temperature-pressure drop ratios within the window was calculated, and the median was recalculated after deleting one temperature-pressure drop ratio in turn. If the absolute value of the difference between the medians before and after deletion in all verification windows corresponding to the same number of candidate samples was not greater than 10% of the reasonable range of temperature-pressure drop ratios, then the number of candidate samples was determined to have passed the verification. The smallest number of candidate samples that passed the verification was determined as the number of samples with the lowest temperature-pressure drop coefficient.

[0054] If the number of effective temperature-pressure drop ratios does not reach the minimum sample size for the temperature-pressure drop coefficient, no new temperature-pressure drop coefficient will be generated. If there is an effective historical temperature-pressure drop coefficient whose formation time is no earlier than the current data start time and is consistent with the current pressure detection benchmark, then this historical temperature-pressure drop coefficient will continue to be used; otherwise, the temperature-pressure drop coefficient status will be determined as unusable, the reference temperature conversion and target low-temperature pressure prediction will be stopped, and the number of effective temperature-pressure drop ratios and the minimum sample size for the temperature-pressure drop coefficient will be recorded. The inspection result will be determined by the final result formation step.

[0055] Temperature cycles are read from morning to night according to their representative time. Only temperature cycles in the normal recovery state are used to form the temperature-pressure drop ratio; temperature cycles in the non-recovery state and the abnormal rise state are not used to form the temperature-pressure drop ratio.

[0056] For any temperature cycle in a normal recovery state, the average of the representative temperature values ​​of the preceding and subsequent temperature comparison segments is determined as the high-temperature representative value, the average of the representative pressure values ​​of the two segments is determined as the high-temperature pressure representative value, and the representative temperature and pressure values ​​of the low-temperature stable segment are determined as the low-temperature representative value and the low-temperature pressure representative value, respectively.

[0057] Determine whether the representative values ​​for high and low temperatures meet the requirements of the calibrated temperature range. (High temperature representative value) It should meet the following requirements: Low temperature representative value It should meet the following requirements: The temperature-pressure drop ratio is calculated only if both temperatures are within the calibrated temperature range, including the upper and lower boundaries. If either representative temperature value is below the lower limit or above the upper limit of the calibrated temperature range, the corresponding temperature cycle is not used for temperature-pressure drop coefficient calculation. The temperature drop is obtained by subtracting the representative low temperature value from the representative high temperature value, and the temperature-induced pressure drop is obtained by subtracting the representative low pressure value from the representative high pressure value. The temperature-induced pressure drop is then divided by the temperature drop to obtain the temperature-pressure drop ratio for that temperature cycle. If the temperature drop is less than the effective temperature drop threshold, the division operation is not performed.

[0058] Temperature pressure drop ratios that are greater than zero and within a reasonable range are selected. When the number of samples that pass the selection reaches the minimum number of samples with the lowest temperature pressure drop coefficient, the median of each temperature pressure drop ratio is determined as the temperature pressure drop coefficient, and the target fire extinguisher identification, the temperature cycle range used, the calibration temperature range, the formation time, and the pressure test benchmark are saved. Temperature pressure drop ratios that fail the selection retain their corresponding temperature cycles and the reasons for failure.

[0059] When a new temperature cycle in a normal recovery state generates an effective temperature-pressure drop ratio, this ratio is added to the set of temperature-pressure drop ratios that are after the current data start time and belong to the same pressure detection benchmark, and the median is recalculated to update the temperature-pressure drop coefficient; when the current data start time or the pressure detection benchmark changes, a new set of temperature-pressure drop ratios is established.

[0060] After the target fire extinguisher has established an effective temperature and pressure drop coefficient, the minimum number of preset trend fitting parameters is read. This minimum number is the minimum number of stable temperature and pressure segments required to fit the linear relationship between pressure and time, and is preset to an integer not less than five. The minimum number of preset trend fitting parameters is determined using normal historical stable temperature and pressure segments. Multiple consecutive verification windows are formed for each candidate number. The original slope is fitted using all stable temperature and pressure segments within the window, and then one stable temperature and pressure segment is deleted and refitted to obtain the deleted slope. The lower limit of the identifiable slope is determined by dividing twice the minimum resolution unit of the pressure sensor by the window time span. The absolute value of the difference between the deleted slope and the original slope is divided by the larger of the absolute value of the original slope and the lower limit of the identifiable slope, and the maximum value is taken as the slope sensitivity. If the slope sensitivity of all verification windows corresponding to the same candidate number does not exceed 20%, and the slope directions of all slopes whose absolute values ​​reach the lower limit of the identifiable slope are consistent, then the candidate number is verified. Slopes with absolute values ​​below the lower limit of the identifiable slope are not included in the direction judgment. The minimum number of candidates that pass the verification is determined as the minimum number of candidates for the preset trend fit.

[0061] Select a stable temperature and pressure range whose representative time is no earlier than the current data start time and whose representative temperature value is within the calibrated temperature range; when there is an abnormal temperature rise cycle, only select stable temperature and pressure ranges after the last data isolation time. When the number of selections reaches the preset minimum number for trend fitting, perform reference temperature conversion and trend fitting; when the number is insufficient, determine the storage pressure drop rate and the pressure converted from the terminal reference temperature as unavailable, and record the current number, the preset minimum number for trend fitting, and the last data isolation time.

[0062] The average value of the upper and lower limits of the calibrated temperature range is quantized according to the smallest resolution unit of the temperature sensor to obtain the preset reference temperature. If the product technical documents of the target fire extinguisher specify a unified reference temperature, and the unified reference temperature is within the calibrated temperature range, then the unified reference temperature is preferentially determined as the preset reference temperature.

[0063] For a selected stable temperature and pressure range, its representative temperature value and representative pressure value are read. First, the representative temperature value of the stable temperature and pressure range is subtracted from the preset reference temperature to obtain the reference temperature difference. Then, the temperature pressure drop coefficient is multiplied by the reference temperature difference to obtain the temperature conversion value corresponding to the stable temperature and pressure range. The temperature conversion value is added to the representative pressure value of the stable temperature and pressure range to obtain the reference temperature converted pressure.

[0064] A correspondence is established between each reference temperature-converted pressure and the representative time of the stable temperature-pressure segment that generates that reference temperature-converted pressure. The data sets are then arranged from earliest to latest according to the representative time. Assume there are n sets of data after sorting, where the i-th set includes the representative time and the reference temperature-converted pressure. To facilitate numerical calculations, the representative time of the first selected stable temperature-pressure segment is designated as the time base. The relative time is obtained by subtracting the time base from the representative time of the i-th stable temperature-pressure segment. All relative times are uniformly converted to hours, days, or other preset time units, and time units must not be mixed within the same trend fitting. The first relative time is zero, and subsequent relative times are positive numbers.

[0065] The least squares method was used to fit the linear relationship between the reference temperature-reduced pressure and the relative time. ,in, Let be the fitted pressure corresponding to the relative time t, a be the intercept of the linear relationship, and b be the slope of the pressure change.

[0066] First, calculate the average value for each relative time and the average value of the pressure converted from each reference temperature: Then the slope of the pressure change is calculated: Calculate the intercept based on the slope of the pressure change: When the representative times are not exactly the same and the number of selected stable temperature and pressure segments reaches the preset minimum number for trend fitting, the denominator Greater than zero. If all representative times are the same or the denominator is zero, the corresponding data cannot form a linear relationship between pressure and time, and the current trend fitting should be stopped.

[0067] When a new stable temperature and pressure range that meets the conditions is added, its reference temperature-converted pressure is added to the current trend fitting data range, and all data within this range are used to refit the pressure change slope and intercept. When a new abnormal upward state causes data isolation, only the reference temperature-converted pressure from the last data isolation time onwards is used for refitting.

[0068] Read the pressure change slope in the linear relationship and determine the rate of pressure drop according to the sign of the slope. When the pressure change slope is less than zero, take the absolute value of the pressure change slope and determine the non-negative number as the rate of pressure drop. When the pressure change slope is greater than or equal to zero, determine the rate of pressure drop as zero.

[0069] The stable temperature and pressure segment with the latest representative time is determined from the stable temperature and pressure segments ordered according to their representative time, and this segment is selected as the last stable temperature and pressure segment. Let the relative time of this stable temperature and pressure segment with respect to the time base be denoted as . ,Will Substitute the existing pressure into the linear relationship of change over time: ,get: ,in, The pressure is calculated based on the terminal reference temperature. The temperature reference for the pressure calculated based on the terminal reference temperature is the preset reference temperature, and the corresponding time is the representative moment of the last selected stable temperature and pressure range.

[0070] After obtaining the temperature pressure drop coefficient, storage pressure drop rate, and terminal reference temperature converted pressure, the applicable temperature range, effective temperature range of the temperature pressure drop coefficient, and allowable data interval of the target fire extinguisher are read, and the predicted ambient temperature sequence of the corresponding installation location after the current inspection time is obtained.

[0071] The applicable temperature range of the target fire extinguisher is denoted as: The upper and lower limits are pre-written into the parameter table based on the minimum and maximum ambient temperatures allowed for storage and operation in the target fire extinguisher's product technical documents. When the target fire extinguisher model or extinguishing agent type changes, the applicable temperature range for the corresponding model should be read. The effective temperature range for the temperature pressure drop coefficient is denoted as: ,in, , in, and These are the representative low-temperature and high-temperature values ​​for the j-th temperature cycle in the coefficient calculation, respectively. Temperature conversion and target low-temperature pressure prediction are only performed within the effective temperature range using the temperature pressure drop coefficient.

[0072] The allowable data interval is preset based on the time interval between representative moments of adjacent stable temperature and pressure segments during normal monitoring, where the representative temperature value is within the calibrated temperature range and belongs to the same pressure detection benchmark. The allowable data interval is the smaller of twice the 95th percentile value and the maximum prediction duration, obtained from the time interval that reaches the preset minimum number of calibrations.

[0073] The installation area identifier is read based on the target fire extinguisher identifier, and the predicted ambient temperature sequence associated with the installation area identifier is obtained through the ambient temperature prediction interface. Each data item includes at least the installation area identifier, predicted ambient temperature value, prediction time, prediction data generation time, and the output resolution unit of the predicted ambient temperature value. Only data items whose prediction time is later than the current inspection time but not later than the end of the maximum prediction duration are retained; for data items with the same prediction time, the data item with the latest generation time is retained, and data items with missing necessary fields are deleted. If the processed predicted ambient temperature sequence is empty, the low temperature prediction status is determined as unavailable and the reason is recorded. The inspection result is determined by the final result formation step.

[0074] From the predicted ambient temperature sequence, select data items whose predicted time is later than the current inspection time but not later than the end of the maximum prediction duration. Compare the predicted ambient temperature values ​​of each selected data item one by one, and determine the minimum value as the target low temperature. When multiple data items have the same minimum predicted ambient temperature value, determine the latest prediction time as the target low temperature time.

[0075] The latest representative time corresponding to the pressure calculated from each reference temperature used to fit the linear relationship between pressure and time is selected as the final representative time. The terminal representative time, terminal reference temperature converted pressure, storage pressure drop rate, and temperature-pressure drop coefficient are saved in the same version. When a new abnormal upward state causes the trend data to be re-divided, only the data after the last data isolation time are used to redetermine the above parameters.

[0076] Before calculating the predicted pressure, the following verifications are performed sequentially: the target low temperature is within the applicable temperature range of the target fire extinguisher; the target low temperature is within the effective temperature range of the temperature-pressure drop coefficient; and the difference between the current inspection time and the terminal representative time is not greater than the allowable data interval. If the first condition is not met, the applicable temperature exceeding the limit indicator is set to valid; if the second or third condition is not met, the low temperature prediction status is determined to be unavailable; if all three conditions are met, the predicted pressure calculation continues. The final result formation step generates a unique inspection result based on the indicator and status.

[0077] After both the range conditions and the data timeliness conditions are met, the temperature difference between the reference temperature and the target low temperature is obtained by subtracting the target low temperature from the preset reference temperature. Then, the temperature pressure drop coefficient is multiplied by the temperature difference to obtain the temperature-induced pressure change at the target low temperature.

[0078] The predicted duration of pressure drop is obtained by subtracting the end-of-line representative time from the target cryogenic time. Since the target cryogenic time is after the current inspection time, and the end-of-line representative time is no later than the current inspection time, the predicted duration of pressure drop is converted to the same time unit as the pressure drop rate. If the pressure drop rate is in pressure units per day, the predicted duration is converted to days; if the pressure drop rate is in pressure units per hour, it is converted to hours. Multiplying the pressure drop rate by the predicted duration of pressure drop yields the amount of pressure drop before the target cryogenic time.

[0079] Pressure converted from terminal reference temperature Starting from, according to Calculate and predict pressure ,in The target is the temperature-induced pressure change at low temperatures. This is the temperature-pressure drop coefficient. For preset reference temperature, To achieve the target low temperature, This represents the decrease in storage pressure. For the target low temperature moment, The end represents the time. It is never less than zero.

[0080] Minimum working pressure The minimum working pressure and the lower limit of the pressure detection mark are determined based on the product technical documents corresponding to the target fire extinguisher model. If the product technical documents simultaneously record the minimum working pressure and the lower limit of the pressure detection mark, the higher value of the two is used. If the product technical documents do not directly record this value, the minimum effective storage pressure boundary determined by the national standard, industry standard, or type test applicable to this type of fire extinguisher is adopted, and the parameter source, applicable model, and version are recorded. If there is no verifiable parameter source, the minimum working pressure and the target cryogenic pressure margin are determined as unusable, and the predicted unusable result is generated by the final result generation step. If the minimum working pressure is available, the target cryogenic pressure margin is calculated. .

[0081] After a new normal recovery temperature cycle is added, the temperature-pressure drop coefficient may be updated; after a new stable temperature-pressure range that meets the calibration temperature range is added, the storage pressure drop rate, the pressure converted from the terminal reference temperature, and the terminal representative time may be updated; after the predicted ambient temperature sequence is updated, the target low temperature and the target low temperature time may also be updated. When any input parameter is updated, the predicted pressure and the target low temperature pressure margin are recalculated based on the latest data belonging to the same pressure detection benchmark, rather than directly adding the correction amount to the original prediction result.

[0082] Before generating inspection results, read the current pressure value, pressure monitoring anomaly flag, applicable temperature exceeding limit flag, latest pressure recovery status, temperature-pressure drop coefficient, storage pressure drop rate, end-point reference temperature converted pressure, and target cryogenic pressure margin and their respective availability status. Judge according to the following order: insufficient current pressure, pressure monitoring anomaly, applicable temperature exceeding limit, insufficient inspection data, unavailable prediction, insufficient target cryogenic predicted pressure, risk of storage pressure drop, and normal pressure status; if any condition is met, write a unique inspection result and stop subsequent judgments.

[0083] The preset pressure confirmation duration is the length of a historical time window used to determine the current pressure status, with the current inspection time as the endpoint. The pressure monitoring data within the preset pressure confirmation time period refers to the pressure value that meets the following conditions at the time of pressure sampling: ,in, For the current inspection time, This represents the pressure sampling time for the j-th pressure value. Pressure values ​​located outside the time interval are not used in the current pressure value calculation.

[0084] The preset pressure confirmation time is determined before the target fire extinguisher is put into inspection, based on the pressure acquisition cycle and the duration of short-term pressure measurement fluctuations. Specifically, under the condition that the target fire extinguisher's pressure storage state and ambient temperature remain stable, pressure monitoring data is continuously acquired. Short-term fluctuations are identified where the pressure value deviates from the median pressure in the stable data range by two minimum resolution units of the pressure sensor, and then returns to within two minimum resolution units above and below the median pressure. The duration of each short-term fluctuation from the start of the deviation to the return time is calculated. The 95th percentile of each duration is added to a nominal pressure sampling cycle to obtain the initial value of the pressure confirmation time. The preset pressure confirmation time is determined according to the following formula: in, The nominal sampling period for pressure monitoring data. This is the 95th percentile of the short-term fluctuation duration. Therefore, the preset pressure confirmation duration should cover at least five nominal pressure sampling periods and be able to cover most short-term pressure fluctuations under normal conditions. The preset pressure confirmation duration should be redefined if the pressure sampling period, pressure sensor model, or data acquisition filter settings change.

[0085] The minimum quantity for current state determination is the minimum number of pressure values ​​required to form the current pressure value within the preset pressure confirmation time, denoted as . The theoretical number of samples is calculated based on the preset pressure confirmation time and the nominal pressure sampling cycle: The theoretical number of samples is compared with five, and the larger of the two is taken as the minimum number of judgments required for the current state. ,in, This indicates rounding down. Using at least five pressure values ​​to calculate the current pressure value avoids representing the current pressure state with only a single or a small number of pressure values. If the preset pressure confirmation time or the nominal pressure sampling period changes, the minimum number of values ​​required for current state judgment is recalculated synchronously.

[0086] According to the target fire extinguisher identification, read the pressure monitoring data within the preset pressure confirmation time, and delete data that exceeds the effective range of the pressure sensor, has missing timestamps, or whose values ​​cannot be parsed. When the number of effective pressure values ​​reaches the minimum number for current status judgment, determine the median of all effective pressure values ​​as the current pressure value; when the number is insufficient, determine the current pressure value status as unavailable, and record the number of effective pressure values, the minimum number for current status judgment, the preset pressure confirmation time, and the reasons for each invalid data. The final result formation step determines the inspection result.

[0087] A preset pressure drop rate threshold is used to distinguish between pressure changes within the normal measurement fluctuation range and a continuous pressure drop trend that needs to form a basis for judging the risk of pressure drop. This threshold is denoted as... The unit of the pressure drop rate is consistent with that of the pressure drop rate, both being pressure units per unit of time. The preset pressure drop rate threshold should be a value greater than zero. Before the target model fire extinguisher is put into inspection, multiple historical data windows of the same model fire extinguishers with normal pressure are selected. The pressure drop rate of each historical data window is calculated according to the aforementioned temperature conversion and linear fitting method, and its 95th percentile value is taken. For each historical data window, twice the minimum resolution unit of the pressure sensor is divided by the difference between the representative times of the first and last stable temperature and pressure segments of that window to obtain the corresponding identifiable drop rate. The larger of the maximum value among the identifiable drop rates and the 95th percentile value is determined as the preset pressure drop rate threshold.

[0088] When the latest pressure recovery status is in a state of decline and not yet recovered, the first criterion for judging the risk of pressure drop is formed; when the rate of pressure drop is in an available state and reaches the preset rate of pressure drop threshold, the second criterion for judging the risk of pressure drop is formed. When either criterion is formed, it is determined that a criterion for judging the risk of pressure drop has been formed; if both are met simultaneously, only one criterion is formed and the reasons for each are recorded. When the latest pressure recovery status or the rate of pressure drop is unavailable due to insufficient valid data, the reason for insufficient inspection data is recorded; when the target cryogenic pressure margin is unavailable due to unavailable predicted ambient temperature, effective temperature range, data timeliness, or minimum operating pressure, the reason for the unavailability of the prediction is recorded. The final result formation steps form a unique result according to the preset priority.

[0089] The inspection result field is initialized to empty, and then the following conditions are checked in sequence: insufficient current pressure, abnormal pressure monitoring, excessive applicable temperature, insufficient inspection data, unusable prediction, insufficient target low temperature predicted pressure, risk of pressure drop in storage, and normal pressure status. If any condition is met, the corresponding result is written and subsequent checks stop; if the condition is not met, the next condition is checked.

[0090] When the current pressure value is less than or equal to the minimum working pressure, a pressure deficiency inspection result is generated. The source of the result is recorded as the current pressure boundary, and the current pressure value, minimum working pressure, current inspection time, and the difference between the two are saved. After the result is generated, subsequent result judgment is stopped.

[0091] If no current pressure deficiency result is generated and the pressure monitoring anomaly indicator is valid, an abnormal inspection data result is generated and subsequent judgment is stopped. A valid pressure monitoring anomaly indicator means that there is an abnormal temperature rise cycle after the current data start time that has not been verified and has not been reset by a status change event. Record the representative time of the most recent abnormal temperature rise cycle, the representative pressure value of the preceding and following isothermal comparison segment, the isothermal pressure difference, the allowable pressure recovery error, and the data isolation time, and retain the historical records of other abnormal temperature rise cycles.

[0092] If the aforementioned results are not achieved, and the target low temperature exceeds the applicable temperature range of the target fire extinguisher, an "applicable temperature exceeding limit" result is generated. If the current pressure value, latest pressure recovery status, temperature-pressure drop coefficient, storage pressure drop rate, or terminal reference temperature converted pressure is unavailable due to insufficient effective data, an "insufficient inspection data" result is generated. If the target low temperature pressure margin is unavailable due to an empty predicted ambient temperature sequence, the target low temperature exceeding the effective temperature range of the temperature-pressure drop coefficient, terminal data exceeding the allowable data interval, or the minimum working pressure being unavailable, a "predicted unusable" result is generated. If none of the aforementioned results are generated and the target low temperature pressure margin is not greater than zero, a "pressure insufficient" inspection result is generated, and the source of the result is recorded as the target low temperature prediction boundary.

[0093] If none of the aforementioned results are achieved and the target cryogenic pressure margin is greater than zero, if the latest pressure recovery status is a non-recovery state or the storage pressure decline rate reaches the preset storage pressure decline rate threshold, then a storage pressure decline risk inspection result is generated; the conditions that are met are recorded as temperature cycle pressure not recovered and long-term pressure decline trend reaching the threshold, respectively, and both conditions are recorded simultaneously.

[0094] A normal pressure status assessment is only performed when none of the aforementioned abnormalities, exceeding limits, insufficient data, unavailable predictions, insufficient pressure, and pressure drop risk conditions are met. A normal pressure status inspection result is generated when the current pressure value is higher than the minimum operating pressure, the latest pressure recovery status is normal, the pressure drop rate is available and has not reached the preset pressure drop rate threshold, the target cryogenic pressure margin is available and greater than zero, and there are no pressure monitoring anomalies in this inspection. A normal pressure status inspection result is not generated if any necessary intermediate result is unavailable.

[0095] When new pressure monitoring data, stable temperature and pressure ranges, effective temperature cycles, status change records, or predicted ambient temperature sequences are added, the data availability judgment and inspection result judgment are re-executed. When any input or intermediate result is updated, a unique inspection result is re-formed based on all currently valid data, without directly overlaying or modifying the original inspection result.

[0096] Example 2: Based on Example 1, this example provides a fire extinguisher intelligent inspection system based on pressure monitoring, such as... Figure 5The diagram shows a framework of an intelligent fire extinguisher inspection system based on pressure monitoring. It includes a temperature and pressure data processing module, used to acquire pressure monitoring data and corresponding ambient temperature data of the target fire extinguisher, forming temperature and pressure time-series data, and determining each stable temperature and pressure segment, as well as the representative temperature value, representative pressure value, and representative time of each stable temperature and pressure segment from the time-series data. A temperature cycle formation module, used to determine the preceding and following temperature comparison segments before and after an ambient temperature deviation, based on the representative temperature values ​​and representative times of each stable temperature and pressure segment, and to determine a low-temperature stable segment between the preceding and following temperature comparison segments, forming a temperature cycle. A pressure recovery state determination module, used to determine the same-temperature pressure difference based on the representative pressure values ​​of the preceding and following temperature comparison segments, and to determine the pressure recovery state of the temperature cycle based on the same-temperature pressure difference. A temperature pressure drop coefficient determination module, used to determine the temperature pressure drop coefficient of the target fire extinguisher based on the temperature and pressure changes corresponding to the preceding and following temperature comparison segments and the low-temperature stable segment in the temperature cycle where the pressure recovery state is normal recovery. The pressure change determination module converts the representative pressure values ​​of each stable temperature and pressure range into reference temperature-converted pressures at a preset reference temperature based on the temperature-pressure drop coefficient. It then determines the pressure drop rate of the target fire extinguisher and the terminal reference temperature-converted pressure based on the changes in the reference temperature-converted pressures over representative times. The low-temperature pressure prediction module determines the predicted pressure of the target fire extinguisher at the target low temperature based on the terminal reference temperature-converted pressure, temperature-pressure drop coefficient, pressure drop rate, predicted target low temperature, and its corresponding time. It also determines the target low-temperature pressure margin based on the predicted pressure and the target fire extinguisher's minimum operating pressure. The inspection result generation module generates inspection results for the target fire extinguisher based on the pressure recovery status, pressure drop rate, and target low-temperature pressure margin of each temperature cycle.

Claims

1. A method for intelligent inspection of fire extinguishers based on pressure monitoring, characterized in that, include: Acquire the pressure monitoring data and corresponding ambient temperature data of the target fire extinguisher to form temperature and pressure time series data, and determine each stable temperature and pressure segment, as well as the representative temperature value, representative pressure value and representative time of each stable temperature and pressure segment from the temperature and pressure time series data; Based on the representative temperature values ​​and representative times of each stable temperature and pressure range, the preceding and following temperature comparison ranges before and after the deviation of the ambient temperature are determined, and the low-temperature stable range is determined between the preceding and following temperature comparison ranges to form a temperature cycle. The pressure difference at the same temperature is determined by the representative pressure values ​​of the first and second isothermal comparison sections, and the pressure recovery state of the temperature cycle is thus determined. Based on the temperature and pressure changes corresponding to the first and second temperature comparison sections and the low-temperature stable section in the temperature cycle when the pressure recovery state is normal, the temperature and pressure drop coefficient of the target fire extinguisher is determined. Based on the temperature pressure drop coefficient, the pressure representative value of each stable temperature and pressure range is converted into the reference temperature conversion pressure at the preset reference temperature, and the pressure drop rate of the target fire extinguisher and the terminal reference temperature conversion pressure are determined based on the change of the reference temperature conversion pressure with the representative time. Based on the terminal reference temperature converted pressure, temperature pressure drop coefficient, storage pressure drop rate, predicted target low temperature and its corresponding time, determine the predicted pressure of the target fire extinguisher at the target low temperature, and determine the target low temperature pressure margin based on the predicted pressure and the minimum working pressure of the target fire extinguisher. Based on the pressure recovery status, storage pressure drop rate, and target low-temperature pressure margin of each temperature cycle, the inspection results of the target fire extinguisher are generated.

2. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 1, characterized in that, The formation of the temperature and pressure time series data includes: Obtain the status change record of the target fire extinguisher, and identify status change events that change the storage pressure state, pressure detection benchmark, or installation environment of the target fire extinguisher from the status change record; Pressure values ​​and ambient temperature values ​​that have the same sampling time or whose sampling time difference does not exceed the allowable time deviation are associated as temperature-pressure data points. The sampling time of the associated pressure value is determined as the sampling time of the temperature-pressure data point, and the temperature-pressure data points are arranged according to the sampling time. The completion time of the most recent state change event is determined as the current data start time; when no state change event exists, the sampling time of the first temperature and pressure data point is determined as the current data start time. Select temperature and pressure data points whose sampling time is between the current data start time and the current inspection time to form the temperature and pressure time series data used for this inspection.

3. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 1, characterized in that, Determine each stable temperature and pressure range from the temperature and pressure time series data, including: A pressure value and an ambient temperature value that correspond to each other are defined as a temperature-pressure data point. Based on the time interval between adjacent temperature-pressure data points, temperature-pressure data points whose time interval between adjacent temperature-pressure data points is not greater than the allowable sampling interval are divided into the same continuous data segment. Candidate data intervals are determined from each continuous data segment, wherein the difference between the maximum and minimum values ​​of the ambient temperature within the candidate data interval is no greater than the temperature stability threshold, and the duration of the candidate data interval is equal to the sum of the thermal response waiting time and the shortest stability time. Remove the data within the thermal response waiting time after the start of each candidate data interval; when the difference between the maximum and minimum pressure values ​​in the remaining data of any candidate data interval is not greater than the pressure stability threshold, and the duration of the remaining data is not less than the shortest stability time, the remaining data is determined as the stable temperature and pressure range; The median of the ambient temperature values ​​in the stable temperature and pressure range is determined as the representative temperature value, the median of the pressure values ​​is determined as the representative pressure value, and the end time of the stable temperature and pressure range is determined as the representative time.

4. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 3, characterized in that, Forming the temperature cycle includes: The stable temperature and pressure ranges are sorted according to the representative time points mentioned above; For the two stable temperature and pressure segments that represent the time earlier and later after sorting, if the absolute value of the difference between their representative temperature values ​​is not greater than the allowable deviation of the same temperature, and there is at least one stable temperature and pressure segment between them, the stable temperature and pressure segments that represent the time earlier and later are respectively determined as the candidate before same temperature comparison segment and the candidate after same temperature comparison segment. The lowest representative temperature value is determined from the stable temperature and pressure range between the candidate pre-temperature comparison segment and the candidate post-temperature comparison segment; When the difference between the lower of the temperature representative values ​​of the candidate pre-temperature comparison segment and the candidate post-temperature comparison segment and the lowest temperature representative value reaches the effective temperature drop threshold, the candidate pre-temperature comparison segment and the candidate post-temperature comparison segment are respectively determined as the pre-temperature comparison segment and the post-temperature comparison segment. When there is only one stable temperature-pressure segment with the lowest representative temperature value between the preceding and following temperature comparison segments, the stable temperature-pressure segment is determined as the low-temperature stable segment; when there are multiple stable temperature-pressure segments with the lowest representative temperature value, the stable temperature-pressure segment with the earliest representative time is determined as the low-temperature stable segment. The temperature cycle is formed by the preceding isothermal comparison segment, the low-temperature stabilization segment, and the subsequent isothermal comparison segment, and the representative moment of the subsequent isothermal comparison segment is determined as the representative moment of the temperature cycle.

5. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 4, characterized in that, Determining the pressure recovery state includes: Obtain the allowable error of basic pressure recovery and the preset upper limit of temperature pressure drop ratio. Multiply the upper limit of temperature pressure drop ratio by the absolute value of the difference between the representative temperature values ​​of the previous and subsequent temperature comparison segments to obtain the remaining allowable pressure change of temperature difference. Add the allowable error of basic pressure recovery to the remaining allowable pressure change of temperature difference to obtain the allowable error of pressure recovery for the temperature cycle. The pressure difference at the same temperature is obtained by subtracting the pressure representative value of the subsequent same temperature comparison section from the pressure representative value of the preceding same temperature comparison section. When the absolute value of the pressure difference at the same temperature is not greater than the allowable error of pressure recovery, the pressure recovery state of the temperature cycle is determined to be the normal recovery state. When the pressure difference at the same temperature is greater than the allowable error for pressure recovery, the pressure recovery state of the temperature cycle is determined to be a state of decline and non-recovery. When the pressure difference at the same temperature is less than the negative of the allowable error for pressure recovery, the pressure recovery state of the temperature cycle is determined to be an abnormal rise state, indicating that there is an abnormality in pressure monitoring during this inspection. When determining the rate of decrease in the storage pressure, the stable temperature and pressure range before and after the temperature cycle are not used together to determine the relationship between pressure and time. The temperature cycle in which the pressure recovery state is normal or in a state of decline and not yet recovered is determined as the effective temperature cycle. The effective temperature cycle with the latest representative time is selected from all effective temperature cycles, and the pressure recovery state of the selected effective temperature cycle is determined as the latest pressure recovery state.

6. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 1, characterized in that, Determining the temperature-pressure drop coefficient includes: Obtain the reasonable range of temperature-pressure drop ratio, the calibration temperature range, and the minimum number of samples with the lowest temperature-pressure drop coefficient; For temperature cycles where the pressure recovery state is in the normal recovery state, the average value of the temperature representative values ​​of the previous and subsequent temperature comparison segments is determined as the high temperature representative value, the average value of the pressure representative values ​​of the previous and subsequent temperature comparison segments is determined as the high temperature pressure representative value, and the temperature and pressure representative values ​​of the low temperature stable segment are determined as the low temperature representative value and the low temperature pressure representative value, respectively. When both the high-temperature representative value and the low-temperature representative value are within the calibrated temperature range, and the high-temperature representative value is greater than the low-temperature representative value, the difference between the high-temperature pressure representative value and the low-temperature pressure representative value is divided by the difference between the high-temperature representative value and the low-temperature representative value to obtain the temperature-pressure drop ratio. Select temperature-pressure drop ratios that are greater than zero and fall within a reasonable range of the stated temperature-pressure drop ratio; When the number of selected temperature-pressure drop ratios reaches the minimum sample size for the temperature-pressure drop coefficient, the median of each selected temperature-pressure drop ratio is determined as the temperature-pressure drop coefficient of the target fire extinguisher.

7. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 6, characterized in that, Determining the rate of decrease in storage pressure and the pressure calculated from the terminal reference temperature includes: Obtain the minimum number of preset trend fitting values, and select stable temperature and pressure segments from each stable temperature and pressure segment whose representative temperature value is within the calibrated temperature range, wherein the number of selected stable temperature and pressure segments reaches the minimum number of preset trend fitting values. For each selected stable temperature and pressure range, the temperature pressure drop coefficient is multiplied by the difference between the preset reference temperature and the temperature representative value of the stable temperature and pressure range, and the resulting product is added to the pressure representative value of the stable temperature and pressure range to obtain the corresponding reference temperature converted pressure. The pressures calculated based on each reference temperature are sorted according to the representative time, and the linear relationship between the pressure and time is fitted based on each representative time and the corresponding reference temperature calculated pressure. When the slope of the pressure change corresponding to the linear relationship is less than zero, the absolute value of the slope of the pressure change is determined as the rate of decrease in the storage pressure; when the slope of the pressure change is greater than or equal to zero, the rate of decrease in the storage pressure is determined as zero. Based on the linear change relationship, the fitting pressure corresponding to the representative moment of the last selected stable temperature and pressure segment is determined, and the fitting pressure is determined as the pressure calculated from the end reference temperature.

8. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 7, characterized in that, Determining the predicted pressure and the target cryogenic pressure margin includes: Obtain the applicable temperature range of the target fire extinguisher, the effective temperature range of the temperature pressure drop coefficient, and the allowable data interval, and obtain the predicted ambient temperature sequence of the target fire extinguisher's location after the current inspection time; The lowest predicted ambient temperature value is selected from the predicted ambient temperature sequence as the target low temperature, and the prediction time corresponding to the target low temperature is determined as the target low temperature time; when the target low temperature corresponds to multiple prediction times, the latest prediction time is determined as the target low temperature time. Select the latest representative time from the representative times corresponding to each reference temperature-converted pressure used to determine the terminal reference temperature-converted pressure, and determine the latest representative time as the terminal representative time; Wherein, the target low temperature is simultaneously within the applicable temperature range of the target fire extinguisher and the effective temperature range of the temperature pressure drop coefficient, and the duration between the end representative time and the current inspection time is not greater than the allowable data interval; Multiply the temperature pressure drop coefficient by the difference between the preset reference temperature and the target low temperature to obtain the temperature-induced pressure change at the target low temperature; Multiply the rate of decrease in storage pressure by the duration between the end representative time and the target cryogenic time to obtain the amount of decrease in storage pressure before the target cryogenic time; The predicted pressure is obtained by subtracting the target low-temperature temperature-induced pressure change and the storage pressure drop from the pressure converted from the terminal reference temperature, and the difference between the predicted pressure and the minimum operating pressure is determined as the target low-temperature pressure margin.

9. The intelligent inspection method for fire extinguishers based on pressure monitoring according to claim 5, characterized in that, The inspection results include: Obtain pressure monitoring data within a preset pressure confirmation time before the current inspection time, preset minimum quantity for current status judgment, preset pressure drop rate threshold, and the applicable temperature range of the target fire extinguisher; When the number of valid pressure values ​​in the pressure monitoring data reaches the minimum number for current state judgment, the median of all valid pressure values ​​is determined as the current pressure value. When the latest pressure recovery status is a declining and unrecovered state, or when the rate of pressure decline in the available state reaches the preset pressure decline rate threshold, a basis for judging the risk of pressure decline is formed. A unique inspection result is generated in the following order: When the current pressure value is available and not higher than the minimum working pressure, a pressure deficiency inspection result is generated. If the aforementioned inspection results are not generated and pressure monitoring anomalies are found during this inspection, an abnormal inspection data result will be generated. If the aforementioned inspection results are not generated and the target low temperature exceeds the applicable temperature range of the target fire extinguisher, an applicable temperature exceeding the limit result is generated. If the aforementioned inspection results are not generated and the current pressure value, the latest pressure recovery status, the temperature-pressure drop coefficient, the storage pressure drop rate, or the terminal reference temperature-converted pressure is unavailable due to insufficient valid data, an inspection data insufficiency result is generated. If the aforementioned inspection results are not generated and the target cryogenic pressure margin is in an unavailable state, a predicted unavailability result is generated. If the aforementioned inspection results are not generated and the target low-temperature pressure margin is not greater than zero, an insufficient pressure inspection result is generated. If the aforementioned inspection results have not been formed but the basis for judging the risk of storage pressure decline has already been formed, an inspection result for the risk of storage pressure decline shall be formed. If the aforementioned inspection results are not generated, and the current pressure value is higher than the minimum working pressure, the latest pressure recovery status is a normal recovery status, the pressure drop rate does not reach the preset pressure drop rate threshold, and the target low temperature pressure margin is greater than zero, a normal pressure status inspection result is generated.

10. A fire extinguisher intelligent inspection system based on pressure monitoring, characterized in that, include: The temperature and pressure data processing module is used to acquire the pressure monitoring data of the target fire extinguisher and the corresponding ambient temperature data, form temperature and pressure time series data, and determine each stable temperature and pressure segment, as well as the representative temperature value, representative pressure value and representative time of each stable temperature and pressure segment from the temperature and pressure time series data. The temperature cycle formation module is used to determine the preceding and following temperature comparison segments before and after the deviation of the ambient temperature based on the representative temperature values ​​and representative times of each stable temperature and pressure segment, and to determine the low temperature stable segment between the preceding and following temperature comparison segments to form a temperature cycle. The pressure recovery state determination module is used to determine the isothermal pressure difference based on the representative pressure values ​​of the previous isothermal comparison section and the subsequent isothermal comparison section, thereby determining the pressure recovery state of the temperature cycle. The temperature and pressure drop coefficient determination module is used to determine the temperature and pressure drop coefficient of the target fire extinguisher based on the temperature and pressure changes corresponding to the first and second temperature comparison sections and the low temperature stable section in the temperature cycle when the pressure recovery state is normal recovery state. The pressure change determination module is used to convert the representative pressure value of each stable temperature and pressure range into the reference temperature conversion pressure at the preset reference temperature based on the temperature and pressure drop coefficient, and to determine the storage pressure drop rate of the target fire extinguisher and the terminal reference temperature conversion pressure based on the change of the reference temperature conversion pressure with the representative time. The low-temperature pressure prediction module is used to determine the predicted pressure of the target fire extinguisher at the target low temperature based on the pressure converted from the terminal reference temperature, the temperature pressure drop coefficient, the rate of pressure drop, the predicted target low temperature and its corresponding time, and to determine the target low-temperature pressure margin based on the predicted pressure and the minimum working pressure of the target fire extinguisher. The inspection result generation module is used to generate inspection results for the target fire extinguisher based on the pressure recovery status, storage pressure drop rate, and target low-temperature pressure margin of each temperature cycle.

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