I. Preparation before calibration
1. Select standard equipment: The accuracy should be one level higher than the sensor, for example, use a 0.1-level standard source to calibrate a 0.5-level sensor.
2. Environmental check: Ensure that temperature, humidity, and air pressure meet requirements. For example, a methane sensor should be zeroed in fresh air.
3. Visual inspection: Clean the sensor surface, gas chamber, and dust filter to prevent dust accumulation from affecting accuracy.
II. Calibration steps
1. Zero point calibration:
Preheat in fresh air for 20 minutes and observe whether the display is zero.
If there is a deviation, use the remote control to select mode "3" and use the "up/down" keys to adjust to zero.
2. Accuracy calibration:
Introduce a standard gas (such as methane) and record the output value.
Use the remote control to select mode "4" and adjust until the displayed value matches the standard value.
3. Alarm value setting:
Select mode "5" and use the "up/down" keys to set the alarm value.
Compare with a portable methane detector; if the error exceeds the tolerance, readjustment is required.
4. Power-off Value Setting:
Select mode "6" and set the power-off value.
The central station operator checks the control input, alarm value, and power-off value for accuracy.
III. Post-Calibration Processing
1. Data Recording: Record the calibration results, including error and adjusted parameters.
2. Labeling: Label calibrated sensors, noting the calibration date and expiration date.
3. Environmental Restoration: Close the gas chamber louvers to prevent dust from entering.
IV. Precautions
1. Safety First: Ensure environmental safety before calibration; power must be disconnected for operations such as in coal mines.
2. Regular Calibration: It is recommended to calibrate every 3-6 months; high-precision sensors require more frequent calibration.
3. Professional Operation: Calibration must be performed by qualified personnel to avoid sensor damage due to misoperation.
