prepare calibration gas: select the standard gas matching the type of gas detected by the combustible gas alarm, and ensure that its concentration is within the working range of the combustible gas alarm and has good stability. Usually, clean air or nitrogen with a purity of not less than 99.99% is used for zero point calibration, and gas standard substance with concentration specified in the instruction manual of combustible gas alarm is used for indication calibration.

Preparation tools: Prepare necessary calibration tools, such as gas flow meter, calibration gas bottle, pressure reducing valve, connecting pipe, etc.

Check the alarm: check whether the appearance of the combustible gas alarm is intact, whether the sensor is clean, and ensure that the combustible gas alarm is in normal working condition.

2. Zero Calibration

Zero Gas: place the combustible gas alarm in clean air (or use a nitrogen cylinder to fill in nitrogen) to ensure that there is no combustible gas in the environment.

Adjust the zero point: adjust the zero point of the combustible gas alarm according to the steps described in the instruction manual of the combustible gas alarm so that the displayed value is zero.

Observe stability: Wait for a period of time (e. g. 5 minutes) and observe whether the value displayed by the combustible gas alarm is stable. If there is a change, repeat the zero adjustment until stable.

3. indication calibration (span calibration)

gas: connect the calibration gas bottle to the gas flow meter, and adjust the gas flow through the pressure reducing valve to gradually increase the calibration gas concentration.

Connect the calibration gas: connect the output of the gas flow meter to the sensor interface of the combustible gas alarm to expose the combustible gas alarm to the calibration gas.

adjust the indication value: after the indication value of the combustible gas alarm is stable, adjust the indication value to the concentration value of the gas standard substance according to the steps described in the instruction manual of the combustible gas alarm. Some combustible gas alarms do not directly adjust the value, but adjust the corresponding coefficient. The coefficient must be calculated and adjusted according to the instructions.

Verify the calibration results: By gradually reducing the calibration gas concentration, observe whether the combustible gas alarm display value returns to zero, and repeat the calibration process several times to ensure the accuracy of the calibration results.

4. recording and identification

record calibration data: record the data in the calibration process, including the indication value before and after calibration, calibration time, calibration personnel and other information.

affix a calibration label: affix a calibration label on the combustible gas alarm, indicating the calibration date, calibration personnel and calibration results.

5. precautions

Regular calibration: according to the use environment and the performance of the combustible gas alarm, the appropriate calibration cycle is formulated to ensure the long-term stable operation of the combustible gas alarm.

Professional operation: The calibration process of the combustible gas alarm should be operated by professionals to ensure the accuracy and safety of the calibration.

compliance: in the calibration process of combustible gas alarm, relevant national and industrial regulations and standards shall be followed, such as "the People's Republic of China Metrology Law" and "verification regulations for combustible gas detection alarm.

In summary, this is the step of calibrating the zero point and indication of the combustible gas alarm. By following the above steps and precautions, we can ensure that the zero point and indication value of the combustible gas alarm are accurately calibrated, thereby improving its detection accuracy and reliability.