Common faults and solutions of gas detectors
Fault 1: Unable to detect at low concentration
Solution:
1. If it is a pump suction measurement, first check whether the pump is working. When the pump is working normally, there is slight vibration, and you can feel significant suction by blocking the air inlet with your fingers for 5 seconds. Then check whether the air inlet is blocked or the connection is not properly sealed, resulting in air leakage and no suction.
2. Inject nitrogen gas to calibrate the zero point or calibrate the zero point in clean air, and immediately perform testing after calibration.
3. After calibrating the zero point, the measured gas cannot be detected, and it is necessary to restore the factory settings.
4. After restoring the factory settings, it cannot be detected. It is necessary to inject nitrogen again or perform zero calibration in clean air. After calibration, the test should be carried out immediately.
5. Check if the connection wire of the sensor has been artificially damaged or has poor contact.
6. The above four steps have been completed but cannot be detected. It is necessary to confirm whether there is any gas being measured on site, or if the concentration of the gas being measured is indeed very low. If it is below the minimum detection limit of the instrument, it cannot be detected.
Fault 2: In the air, there is no measured gas, but the value fluctuates greatly or jumps randomly
Solution:
1. Generally, a short time zero point fluctuation range less than 1% of the maximum range is considered a normal range, and a long time drift less than the maximum range without the measured gas is considered a normal range
2% is within the normal range. If it exceeds this range, it is necessary to confirm whether there is any gas being measured on site, or if the temperature and humidity in the air fluctuate significantly, resulting in unstable values. Generally, temperature and humidity fluctuations can cause short-term and significant fluctuations in the instrument's detection values. After the temperature and humidity in the air remain constant, the values will also be relatively stable.
2. Confirm whether the instrument has undergone zero calibration or target point calibration. If zero calibration is performed in the presence of the measured gas, low concentration gas may not be detected. If target point calibration is performed in the presence of the measured gas, but the calibrated concentration value does not match the actual concentration value, it may cause significant fluctuations in the instrument value or the detected value to be too small, Both cases can be resolved by restoring the factory operation.
3. If the problem cannot be solved after restoring the factory settings, it is necessary to confirm whether the power supply of the detector is sufficient. Do not use a transformer to power the instrument. Instead, use a DC stabilized power supply or switch power supply, and the power should be greater than 24V, 1A (for single device power supply). Multiple devices require higher power, and the wire diameter of the power cord should not be too small, The wire diameter for short distance power supply to a single device is better than 0.75 square millimeters.
4. Check the routing of the signal transmission line to see if it passes through high-power fans, motors, frequency converters, and other areas that may cause electromagnetic field changes. Try to avoid areas with strong electricity and electromagnetic fields as much as possible, and use shielded wires as the signal transmission line. One end of the shielding layer should be connected to the instrument casing, and the other end should be grounded to ensure good grounding.
Fault 3: Inaccurate detection
Solution:
1. Confirm whether the gas concentration on site is accurate. Sometimes, there is a significant difference between the theoretical value and the actual value. It is better to verify the accuracy of the instrument by introducing standard gas or sending it to a third-party measuring institution for testing.
2. If the sensor is used for a long time, there may be some errors in the measured values. It is necessary to confirm with the manufacturer whether the sensor can still be used. If the sensor itself is approaching its service life, even if it can be used normally after calibration, it is recommended to replace the sensor.
