Issues that need to be paid attention to when using gas detectors

At present, with the development of manufacturing technology, portable multi-gas (composite) detection instruments are also a new choice for us. Since this kind of detection instrument can be equipped with multiple gas (inorganic/organic) detection sensors required on a host, it has the characteristics of small size, light weight, fast response, and simultaneous multi-gas concentration display. More importantly, the price of pump suction composite gas detector is cheaper than multiple single diffusion gas detectors, and it is more convenient to use. It should be noted that when choosing this type of detection instrument, it is best to choose an instrument with the function of switching each sensor separately to prevent the damage of one sensor from affecting the use of other sensors. At the same time, in order to avoid the blockage of the suction pump due to water inflow, it is also safer to choose an instrument with an intelligent pump design with a pump stop alarm.

1) Pay attention to regular calibration and testing.

Toxic and harmful gas detectors are also measured by relative comparison method like other analytical detection instruments: first calibrate the instrument with a zero gas and a standard concentration of gas, and obtain a standard curve stored in the instrument. During the measurement, the instrument compares the electrical signal generated by the concentration of the gas to be measured with the electrical signal of the standard concentration to calculate the accurate gas concentration value. Therefore, zeroing the instrument at any time and calibrating the instrument regularly are essential tasks to ensure accurate instrument measurements. It should be noted that many gas detectors can replace detection sensors at present, but this does not mean that a detector can be equipped with different detector probes at any time. Whenever the probe is replaced, in addition to a certain sensor activation time, the instrument must be recalibrated. In addition, it is recommended that the instrument be tested for response with standard gas before using various instruments to ensure that the instrument truly plays a protective role.

2) Pay attention to the detection interference between various sensors.

Generally speaking, each sensor corresponds to a specific detection gas, but no gas detector can be absolutely effective. Therefore, when choosing a gas sensor, you should try to understand the detection interference of other gases on the sensor to ensure its accurate detection of specific gases.

3) Pay attention to the life of various sensors:

various gas sensors have a certain service life, that is, life. Generally speaking, in portable instruments, LEL sensors have a longer lifespan, generally about three years; photoionization detectors have a lifespan of four years or longer; electrochemical specific gas sensors have a relatively short lifespan, generally one to two years; oxygen sensors have the shortest lifespan, about one year. The lifespan of an electrochemical sensor depends on the drying up of the electrolyte, so if it is not used for a long time, sealing it in a lower temperature environment can extend its service life to a certain extent. Fixed instruments have a relatively large volume and a longer sensor lifespan. Therefore, the sensor should be tested at any time, and used as much as possible within the valid period of the sensor. Once it fails, it should be replaced in time.

4) Pay attention to the concentration measurement range of the detection instrument:

All types of toxic and harmful gas detectors have their fixed detection ranges. Only by completing the measurement within its measurement range can the instrument be accurately measured. If the measurement is performed beyond the measurement range for a long time, it may cause permanent damage to the sensor.

For example, if the LEL detector is accidentally used in an environment exceeding 100% LEL, the sensor may be completely burned. And toxic gas detectors can also be damaged if they are used at high concentrations for a long time. Therefore, if a fixed instrument sends an over-limit signal during use, the measuring circuit must be shut down immediately to ensure the safety of the sensor.

Table 1 Concentration detection range, resolution, allowable concentration and maximum tolerance concentration (ppm) of common gas sensors

In short, toxic and harmful gas detectors are powerful tools to ensure industrial safety and the health of workers. We should choose the appropriate gas detector according to the specific use environment and the required functions. At present, the detectors available for us to choose include a variety of combinations such as fixed/portable, diffusion/pump suction, single gas/multi-gas, inorganic gas/organic gas, etc. Only by choosing the right gas detection instrument can we truly achieve twice the result with half the effort and prevent problems before they happen.