Electrochemical gas sensors generate an electrical current through a chemical reaction with specific gases to detect gas leaks and measure their concentration. They consist of an inlet, detection, and backing section, and require regular maintenance and calibration to ensure accurate measurement and reliability. These sensors play an important role in safety and environmental protection in industrial sites, homes, environmental monitoring systems, and more.
Electrochemical gas sensors are devices that use an electrical current generated by a chemical reaction to detect specific gases. They detect gas leaks and measure concentration by measuring the amount of current generated as the incoming gas interacts with the sensor’s electrodes in a redox reaction.
Electrochemical gas sensors typically consist of an inlet, a sensing, and a backing section. The inlet section is responsible for filtering out impurities other than the gas you want to detect when gas enters the sensor and consists of a dust filter, interfering gas filter, and separator. When gas leaks from the air and enters the sensor’s inlet, non-gaseous impurities such as dust and water are first filtered out by the dust filter, and only gaseous gas is sent to the interference gas filter. The interference gas filter then adsorbs gases that interfere with the detection of a specific gas, and only the gas you want to detect passes through the filter and is sent to the separator. The separator is a device that separates the inlet and detection sections, and the gas from the interference gas filter flows through the separator to the detection section for accurate measurement.
The detection part is responsible for generating a current through a redox reaction when gas enters and consists of an action electrode, a response electrode, and a reference electrode. The current generated by the reference electrode is constant during normal operation, and the electrodes of the sensing section are immersed in water with electrolyte dissolved in it. When dissolved in water, the electrolyte acts as a medium that enables the movement of electrons to generate current. The gas that passes through the separator and reaches the sensing part first reacts with the water at the working electrode, where it undergoes an oxidation reaction to produce hydrogen ions and electrons. To actively induce this oxidation reaction, the working electrode is shaped like a porous membrane with multiple holes and is coated with a catalyst such as platinum to increase the rate of the oxidation reaction. The hydrogen ions and electrons generated by the oxidation reaction are transported to the counter electrode using the electrolyte as a medium, where they combine with oxygen supplied from the oxygen inlet at the rear of the electrode to form water, which is then subjected to a reduction reaction. During this process, a current is generated as much as the amount of electron transfer between the action electrode and the counter electrode, and the amount of current generated is proportional to the concentration of the gas introduced.
Finally, the rear part is mainly responsible for checking for gas leakage and measuring the concentration of leaked gas through the current generated by the detection part, and consists of a capacitor, sensor pin, and oxygen inlet. The newly generated current from the sensing part is collected by the capacitor and moved to the sensor pin. The sensor pin compares the amount of newly generated current with the amount of normal current flowing, and if the amount of newly generated current is higher, a gas leak is detected and the concentration of gas is measured.
Meanwhile, if the gas detected by the gas sensor is above the reference concentration, the alarm associated with the sensor will sound an alarm to notify you. There are two types of alarms: immediate and delayed alarms. Immediate alarms are triggered as soon as the gas concentration reaches the alarm threshold set on the sensor. This is often used when the gas itself is dangerous, such as toxic gases. The delayed alarm type does not alarm immediately when the concentration of the detected gas exceeds the alarm setting, but rather alarms when the concentration of the gas remains above the alarm setting for a certain delay time. This is characterized by not alarming in temporary gas leakage situations, such as when a high concentration of gas is detected momentarily, such as when a gas stove ignition malfunction occurs.
To maintain accurate measurement and reliability, electrochemical gas sensors require regular maintenance and calibration. The sensor’s filters or electrodes can deteriorate over time, so they should be checked and replaced regularly. The electrodes in particular can become contaminated or worn depending on the environment in which they are used, so it is important to clean or replace them periodically. In addition, the sensor’s accuracy is maintained by periodically performing calibration, which is the process of comparing and adjusting the sensor’s response using a standard gas to ensure that the sensor maintains accurate measurements.
These electrochemical gas sensors are widely used in a variety of industries and play an important role in gas leak detection and safety management. For example, in industrial sites, they can quickly detect leaks of flammable or toxic gases to protect the safety of workers; in homes, they can detect gas leaks that may occur from gas stoves or boilers to prevent fires or poisoning; and in environmental monitoring systems, they measure the concentration of pollutants in the air to provide data for environmental protection and public safety.
In conclusion, electrochemical gas sensors are important devices that quickly and accurately detect gas leaks, playing an essential role in safety and environmental protection in a variety of applications. They can help prevent gas leakage accidents in industrial sites, homes, and public spaces, and maintain a safer and healthier environment.
