What are the common faults of fixed gas detectors? How to solve them?

Gas detector is an instrument tool for gas leakage concentration detection, including: portable gas detector, handheld gas detector, fixed gas detector, online gas detector, etc. The main function of fixed gas detector is to monitor harmful gases in the air in real time, so as to ensure the health and safety of personnel. So what are the common faults of fixed gas detectors? How to solve them? The following editor of Zetron Technology will introduce them to you.

Common faults and solutions of fixed gas detectors:

(1) The concentration value of the instrument in clean air is unstable, fluctuates, and a small amount of value is displayed

Cause of fault: Some electrochemical gas sensors are easily interfered by other gases, and the interfering gas may be colorless and odorless

Solution: Place the instrument in a clean place without interfering gas, and the instrument value will drop to the normal value;

If it is determined to be a clean place, the value still cannot be reduced, and a zero point calibration can be performed once.

(2) When the instrument is fed with gas for testing, the value does not respond or the response is very weak.

Fault cause: The oxygen content of the gas fed in may be too low: <5%VOL;

The gas pressure may be too negative and the air pump cannot pump it out;

The service life of the sensor may have expired, or the detector may have a fault;

Solution: If it is an electrochemical, catalytic combustion, or semiconductor gas sensor, oxygen is required to work properly. Ensure that the oxygen content of the gas fed in is >5%VOL, and the gas pressure is: -30Kpa ~ 100Kpa. If the user has standard gas, he can feed the gas for testing and perform target point calibration. If the oxygen and pressure meet normal conditions, it may be that the sensor is faulty and needs to be returned to the factory for repair.

(3) After the gas is fed in, the value of the instrument cannot be stabilized for a long time, or it is sometimes high and sometimes low.

Fault cause: Generally, it is caused by the low oxygen content of the gas fed in; it may also be that the gas concentration itself is changing.

Solution: Increase the oxygen content of the gas and stabilize the flow rate; or replace the standard gas with a high oxygen content for testing. (4) 4-20mA output is abnormal, with <4mA or >20mA

Cause of failure: The multimeter or ammeter used for testing may have quality problems, or the chip related to the detector may be faulty

Solution: After confirming that the testing equipment and testing methods are correct, if there is still a problem, return to the factory for repair

(5) The detector cannot connect with the host computer software, controller, etc. during RS485 communication

Cause of failure: The host computer software parameters may be incorrectly set, the address of the detector and the host computer software or controller is inconsistent, the positive and negative connections of the detector RS485 are reversed, there are repeated addresses when multiple detectors communicate, line faults, and the RS485 output of the detector fails

Solution: After confirming that the detector address, host computer software and controller parameters are set correctly, and the line is OK, if communication still fails, return to the factory for repair

(6) The instrument cannot be turned on

Cause of failure: Generally, the power cord is connected in reverse, or the voltage is too low, or the power cord has poor contact

Solution: Use a multimeter to test the terminal V of the detector and V-, make sure there is 24V DC power input

If there is no power, please check whether the circuit or power adapter is normal and whether the wiring terminals are in good contact

If it still cannot be turned on, it needs to be returned to the factory for inspection.

The above common faults and solutions for fixed gas detectors are shared here. I hope this article will be helpful to everyone. If you have other questions about fixed gas detectors, you can follow Zetron Technology or leave a message to the editor. We look forward to discussing with you!