Four Key Points for Attention When Using Gas Detectors
① Perform Regular Calibration and Testing Toxic and hazardous gas detectors, like other analytical instruments, operate on the comparative measurement principle. The device is first calibrated with zero gas and standard concentration gas, and the standard curve is stored in the detector's memory. During measurement, the instrument compares the electrical signal generated by the target gas with the signal of the reference standard gas to calculate the accurate concentration value. Therefore, frequent zero reset and routine calibration are indispensable to guarantee measuring precision.
It should be noted that although most gas detectors support sensor replacement, different sensor probes cannot be arbitrarily matched to one detector. Whenever a probe is replaced, sufficient activation time for the new sensor is required, followed by a full recalibration of the instrument. It is also recommended to conduct a response test with calibration gas before each use to ensure the detector functions reliably for safety protection.
② Be Aware of Cross-Interference Among Different Sensors Generally, each sensor is designed to target one specific gas, yet no gas detector features absolute exclusive selectivity. When selecting a gas sensor, it is necessary to fully understand the interference caused by other gases to ensure accurate detection of the designated substance.
③ Pay Attention to the Service Life of Various Sensors All gas sensors have a limited service life. For portable devices:
LEL sensors have the longest lifespan of approximately three years;
Photoionization detectors (PID) can last four years or longer;
Electrochemical specific gas sensors have a relatively shorter service life of 1 to 2 years;
Oxygen sensors have the shortest service life, roughly one year.
The service life of electrochemical sensors is determined by the evaporation of internal electrolyte. Sealing and storing them in a low-temperature environment during long-term inactivity can extend their service life to a certain degree. Fixed detectors have a larger overall structure, so their sensors generally enjoy a longer service cycle. Sensors shall be inspected periodically, operated within their valid period, and replaced immediately once they malfunction.
④ Observe the Concentration Measuring Range of Detectors Every toxic and hazardous gas detector has a fixed measurable range. Accurate results can only be obtained within the rated measuring scope. Long-term over-range operation may lead to permanent damage to the sensor.
For instance, an LEL detector may suffer complete burnout if accidentally operated in an atmosphere above 100% LEL. Toxic gas detectors will also be damaged under prolonged exposure to excessively high gas concentrations. Accordingly, if a fixed detector triggers an over-range alarm during operation, disconnect the measuring circuit right away to prevent permanent damage to the sensor.
