Guidelines for Choosing Appropriate Toxic and Hazardous Gas Detectors
① Perform regular calibration and testing. Like other analytical testing instruments, toxic and harmful gas detectors adopt the relative comparison method for measurement. The instrument is calibrated with zero gas and standard concentration gas first, and the standard curve is stored inside the device. During measurement, the instrument compares the electrical signal generated by the target gas concentration with that of the standard gas, and calculates the accurate gas concentration value. Therefore, zeroing the instrument at any time and carrying out routine calibration are indispensable steps to guarantee measuring accuracy. It should be noted that although the sensors of most gas detectors are replaceable, it does not mean one detector can be arbitrarily matched with different sensor probes. Whenever a probe is replaced, apart from a required sensor activation period, the instrument must be recalibrated completely. In addition, it is recommended to conduct a response test with standard gas before operation to ensure the detector can provide effective protection.
② Avoid cross-interference between different sensors. Generally, each sensor is designed for a specific target gas, yet no gas detector features absolute exclusive selectivity. When selecting a gas sensor, fully understand the interference caused by other gases to the sensor so as to ensure precise measurement of the designated gas.
③ Pay attention to the service life of different sensors. All gas sensors have a limited service life. For portable instruments, the LEL sensor has the longest lifespan of approximately 3 years; PID (Photoionization Detector) sensors can last 4 years or longer; electrochemical specific gas sensors have a relatively shorter service life of 1 to 2 years; oxygen sensors have the shortest lifetime of around 1 year. The service life of electrochemical sensors is determined by the drying degree of internal electrolyte. If the device will be idle for a long time, sealing and storing it in a low-temperature environment can extend its lifespan to a certain extent. Fixed detectors have larger overall size and accordingly longer sensor service life. Regularly inspect sensors, use them within their valid period, and replace them immediately once they fail.
④ Observe the concentration measuring range of the detector. Each type of toxic and harmful gas detector has a fixed measuring range. Accurate results can only be obtained when the measured concentration falls within the rated range. Long-term over-range measurement will cause permanent irreversible damage to the sensor
