Common Faults and Troubleshooting Methods of Fixed Gas Detectors
(1) The concentration value of the instrument in clean air is unstable, fluctuating high and low, with a small amount of numerical display
Reason for malfunction: Some electrochemical gas sensors are susceptible to interference from other gases, and the interfering gases may be colorless and odorless
Solution: Place the instrument in a clean area without interfering gases, and the instrument value will decrease to normal;
If it is confirmed to be a clean place and the value cannot be reduced, zero calibration can be performed once.
(2) When the instrument is tested with gas, there is no response or the response is very weak
Reason for malfunction: It may be due to the low oxygen content of the introduced gas:<5% VOL;
It may be due to the excessive negative pressure of the gas, which makes it difficult for the air pump to extract it;
It may be due to the expiration of the sensor's service life or a malfunction of the detector;
Solution: If it is an electrochemical, catalytic combustion, or semiconductor gas sensor, oxygen is required for normal operation. The oxygen content of the introduced gas is greater than 5% VOL, and the gas pressure is between -30Kpa and 100Kpa. If the user has standard gas, gas testing can be conducted and target point calibration can be performed. If the oxygen and pressure meet normal conditions, it may be a sensor malfunction that needs to be returned to the factory for repair.
(3) After introducing gas, the instrument's values remain unstable for a long time or fluctuate intermittently
Reason for malfunction: Generally caused by low oxygen content in the gas being introduced; It is also possible that the gas concentration itself is changing.
Solution: Increase the oxygen content of the gas and stabilize the flow rate; Or replace it with a standard gas with high oxygen content for testing.
(4) The 4-20mA output is abnormal, with situations of<4mA or>20mA occurring
Reason for malfunction: It is possible that the multimeter and ammeter used for testing have quality issues, or it is possible that the chip related to the detector has malfunctioned
Solution: After confirming that the testing equipment and methods are correct, if there are still problems, return to the factory for repair
(5) The detector cannot be connected to the upper computer software, controller, etc. through RS485 communication
Fault cause: It may be due to incorrect parameter settings of the upper computer software, inconsistent addresses between the detector and the upper computer software or controller, reversed positive and negative connections of the detector RS485, address duplication during communication between multiple detectors, line faults, or malfunction of the detector RS485 output
Solution: If communication still does not work after confirming the correct settings of the detector address, upper computer software and controller parameters, and the circuit is OK, it is necessary to return to the factory for repair
