1、 Clarify the benchmark for "measurement progress requirements": first establish the "qualified standards"

The prerequisite for determining whether the progress meets the requirements is to first clarify "what meets the requirements" - it is necessary to combine the measurement purpose, industry standards, and instrument instructions to determine the core indicators related to the progress. Common benchmarks include:

Time dimension: such as "response time" (the time it takes for the instrument to reach a stable reading of 90% after coming into contact with the target gas, which should be ≤ the value indicated in the instruction manual. For example, catalytic combustion detectors usually require ≤ 30 seconds to measure combustible gases), "measurement cycle" (such as online detectors that need to refresh data every 10 seconds, and offline detectors that need to complete a single sampling and analysis within 5 minutes);

Data dimensions: such as "stability requirements" (when measuring continuously, the reading fluctuation amplitude should be ≤± 2% FS, which is 2% of the full scale), "accuracy requirements" (the deviation between the measured value and the true value should be ≤± 5%, such as when the standard gas concentration is 100ppm, the instrument reading should be within the range of 95-105ppm);

Process dimension: such as "Calibration cycle compliance" (if the instrument requires calibration every 3 months, it is necessary to confirm that the last calibration time has not expired, otherwise the measurement progress will change from "valid" to "calibration needs to be paused").

In short, there needs to be a "clear progress indicator table" first (such as "completing sampling and reading within 5 minutes, data fluctuation ≤ ± 3%"), and then comparing and judging.

2、 Real time monitoring of "measurement process nodes": check if the steps are progressing in sequence

The measurement of gas detectors usually follows the process of "start-up preheating → zero calibration → sampling → stable reading → data recording", and each node has a "standard time consumption". The progress can be judged by "node time consumption comparison" to determine whether it is normal:

Power on preheating stage: Most instruments require preheating (such as electrochemical sensors requiring 10-30 minutes and infrared sensors requiring 5-15 minutes). If the instruction manual requires "measurement after preheating for 20 minutes", but only starts sampling after preheating for 5 minutes, even if the subsequent readings "appear normal", it is still a "progress violation" - the sensor is unstable and the data accuracy is not guaranteed;

Sampling and reading stage: It is necessary to observe the "data change trend": under normal circumstances, after the instrument comes into contact with gas, the reading should gradually rise/fall from the initial value (such as zero), and eventually stabilize (fluctuation within 1 minute is ≤± 1%). If there is still a severe fluctuation after 30 seconds (such as jumping from 50ppm to 120ppm and then falling back to 30ppm), or if it exceeds the "response time" specified in the manual (such as stable after 20 seconds, but still not stable after 50 seconds), it is considered as "abnormal progress" and needs to be investigated (such as sensor aging, sampling pump blockage);

Data recording stage: If it is a batch measurement (such as detecting multiple points), it is necessary to confirm whether the "time consumption of a single point is controllable": for example, it is required that "each point takes ≤ 2 minutes from sampling to recording completion". If a certain point takes more than 5 minutes due to instrument lag or data transmission delay, the overall progress does not meet the "efficiency requirements" and needs to be adjusted (such as restarting the instrument or switching to manual recording).

3、 Verify the validity of progress through "standard gas verification": using known values to deduce the process

Even if the measurement process progresses over time, it is necessary to confirm whether the "data quality" corresponding to the progress is qualified through "standard gas calibration/verification" - this is the core of judging whether the progress has practical significance:

Calibrate the zero/range with standard gas before measurement: If the instrument needs to be calibrated first (such as when used for the first time every day), observe whether the "calibration progress meets the standard": for example, when calibrating the range with 100ppm standard gas, the instrument should complete the "reading → comparison → automatic correction" process within 5 minutes, and the deviation between the corrected reading and the concentration of the standard gas should be ≤ ± 2%. If the calibration takes more than 10 minutes, or the deviation still reaches 10% after correction, it indicates "abnormal calibration progress" and needs to be investigated (such as expired standard gas or sensor failure). At this time, formal measurement cannot be entered;

Verification of inserting standard gas during measurement: During continuous measurement (such as online monitoring), a known concentration of standard gas can be periodically introduced (such as every 2 hours) to observe whether the instrument reads the accurate value within the specified time. For example, after introducing 50ppm standard gas, it is required that the reading be stable at 48-52ppm within 30 seconds. If the reading is still 40ppm after 1 minute, it indicates that the "real-time measurement progress is invalid" (although the instrument is continuously reading, the data is inaccurate), and the measurement needs to be paused and repaired;

Verify with parallel samples after measurement: For offline samples (such as collected gas samples), data consistency can be checked by "repeated measurement 3 times": if the relative standard deviation (RSD) of the 3 measurements is ≤ 5%, it indicates that the measurement process is stable (the progress meets the "repeatability requirements"); If the RSD exceeds 10%, even if the single measurement time meets the requirements, it is considered as "progress invalid" (data unreliable).

4、 Troubleshooting "Environmental and Operational Interference": Distinguishing the Causes of "Abnormal Progress"

If it is found that the progress does not meet the requirements (such as slow response, large data fluctuations), it is necessary to first eliminate "external interference" to avoid misjudging the instrument itself:

Environmental factors: temperature (such as exceeding the working temperature range of the instrument by -20~50 ℃, sensor activity decreases, response time prolongs), humidity (high humidity may cause electrochemical sensors to become damp and readings to drift), gas interference (such as when measuring "carbon monoxide", if there is a high concentration of hydrogen sulfide, it may suppress the sensor and cause reading delay);

Operational factors: Whether the sampling method is correct (such as placing the diffusion detector in a gas flow area, if it is placed in a dead angle, the sampling efficiency is low; for the pump suction detector, it is necessary to confirm that the sampling pump flow rate is normal. If the flow rate drops from 500mL/min to 200mL/min, the sampling progress will slow down), whether the instrument placement is stable (if it vibrates violently, it may cause poor sensor contact and data fluctuations);

Instrument status: Whether the battery level is sufficient (low battery may cause insufficient power of the sampling pump and data transmission lag), whether the filter is clogged (such as clogged dust filter, gas cannot enter the sensor smoothly, and response time is prolonged).

For example, if the response time of the instrument suddenly changes from 20 seconds to 1 minute, and it is found through investigation that the dust accumulation at the inlet filter of the sampling pump is the cause, and it returns to normal after cleaning, it belongs to "abnormal progress caused by operation and maintenance" rather than the instrument itself.