How to Calibrate the Multi-Gas Detector?

As a security detection equipment, the multi-gas detector can be used to detect the concentration of flammable gas, toxic and harmful gases in the environment, which is a measuring instrument for compulsory verification that is widely applied to petroleum, petrochemical industry, aviation, chemical, chemical engineering, metallurgy and other fields. Since there are various kinds of gas detectors, which have a wide range of applications, short service life of sensor elements and large differences in performance, the performance and quality of gas detectors are directly related to the personal safety of employees on the work site as one of the guarantees of safe production. Therefore, it is an important measure to ensure personal safety and property safety by adopting scientific and reasonable detection methods for different instruments.

Since the multi-gas detector is a safety detection equipment. To ensure the safety of users, it must be verified or calibrated before the use. At present, there are many kinds of multi-gas detectors in the market, as well as different methods of verification and calibration, so it is necessary to read the instructions and verification rules carefully before calibration so as to adopt the correct method to calibrate the instrument.   

Verification conditions. According to the requirements of specification, the ambient temperature must be maintained at (0~40)℃ and the relative humidity is less than or equal to 85% without electromagnetic interference. Furthermore, the gas flow controller must meet the requirements of instrument verification, and the pump-suction type must be equipped with bypass flow meter to ensure that the bypass flow meter in the flow controller has flow to empty. In order to make the intake flow coincide with flow sucked by the pump of the instrument, the air flow should be controlled well. Diffusion flow should be controlled according to the requirements of instrument instructions, if the instrument specification does not specify, it is generally controlled in the range of (250±50) mL / min. Attention: different detectors should use the appropriate standard gas hood, because a suitable gas hood has a great influence on the results of verification and calibration. For semiconductor and catalytic combustion, the base gas of standard gas must be air with calibrated concentration and the instrument must have a fixed calibration point. Meanwhile, the corresponding standard gas must be prepared for calibration according to the fixed standard gas concentration of the instrument.

Common problems. Since some instruments have set the calibration cycle, when the instrument is used longer than the calibration cycle, the instrument will alarm or display failure. At this moment, the instrument should be re-calibrated.  In addition, when exceeding the measuring range or negative shift appears, or the concentration of oxygen is less than 10 vol% and flammable, the instrument will display failure. For gases beyond the measuring range, the sensitivity of gases may be temporarily enhanced, so it is necessary to calibrate the instrument after it has been restored for a certain period of time. When the gas detector display "———" on start-up, it is usually sensor failure or needs to be re-calibrated.