The gas detector can detect the leakage of gas, and remind people to take safety measures such as refuge, forced exhaust, and shut down equipment by sending out alarm signals such as sound and light. It is an indispensable equipment for industrial production and daily life.

However, gas detectors do not always measure gas concentration correctly. Just as our watch needs regular and standard time correction, the gas detector also needs regular correction to ensure the correctness of the detection. The correction process is called standard.

The accuracy of the combustible gas alarm is an important prerequisite for detection and alarm. Its accuracy depends on the built-in combustible gas sensor. Whether it is an electrochemical sensor or a catalytic combustion sensor, it will be affected by substances in the environment in use, and gradually change and poisoning faults will occur. Through timely maintenance and correction, the accuracy of the results detected by the instrument will be ensured.

In actual use, many factors will affect the accuracy of the alarm. Regular calibration is to minimize the error of the detection result and maximize the accuracy.

1, the oxygen concentration is too high or too low.

When detecting combustible gas in an oxygen-deficient atmospheric environment, the concentration of combustible gas may be lower than the actual concentration. On the contrary, when detecting in an oxygen-deficient environment, the detected concentration may be higher than the actual concentration.

In this case, in order to achieve the purpose of correct measurement, the detector needs to be calibrated.

2. Re-calibration of combustible gas detector.

When the gas concentration is too high, the combustible gas detector shows an over-range, it needs to be calibrated again. In the process of using the combustible gas detector, the measuring range of the instrument is 0-100% LEL. If the actual concentration exceeds 100%, it will cause over-range phenomenon. At this time, the gas detector needs to be re-calibrated.

Water vapor or other known impurities of silicon compounds may affect the normal operation of the combustible gas detector, causing its reading to be lower than the actual gas concentration. If the instrument has been used in a water vapor environment of silicon compounds, in order to ensure the correctness of the measurement, the instrument will be recalibrated before the next use.

According to the lower explosive limit of each detected gas, we need to calibrate it purposefully.

Taking the hydrogen alarm as an example, we must first complete the production of hydrogen standard gas, and the rated sensitive element or application product is energized and aged for a period of time under rated working conditions (usually not less than 2 hours, preferably more than 24 hours) to fully stabilize the resistance value of the element.Put the gas-sensitive components and application products of the detector into the test chamber, and inject the gas and liquid to be tested with the sample device (medical syringe can be used) according to the volume requirements to form a calibrated gas in the test chamber. Adjust the circuit preset mechanism such as variable resistor on the application product to make the application product trigger (such as alarm). Exhaust the test gas from the test chamber with an exhaust fan, repeat 2 to 4 times, and confirm that the application product is just triggered.

The following items should be noted when specifying gas detectors:

1. calibration environmental conditions. The gas alarm is an electronic instrument, and the error in its detection mainly comes from the detection environment. Requirements for good ventilation, calibration without interference, the environment and temperature need to reach a certain value.

2. calibration flow control.Gas alarms are mostly catalytic combustion sensors, and the size of the flow directly affects the accuracy of the verification results, so it is necessary to control the flow. Too large or too small flow will affect the calibration results.

The display value of the main controller and the field detector is inconsistent during 3. calibration. When the gas concentration of the gas detector in the environment reaches or exceeds the preset alarm value, the main controller will immediately alarm to remind the personnel on duty to take safety measures to ensure the safety of the enterprise.

Calibration cover for 4. calibration. When calibrating the flammability and toxic gas alarm, use the calibration cover. Each manufacturer has its own special calibration cover. When calibrating, it is best to use the calibration cover produced by the factory, and the calibration result is more accurate. In addition, in order to ensure the correctness of the inspection, gas alarm at least once a year.