Four categories of electrochemical gas detection instruments
A considerable part of flammable, toxic and harmful gases are electrochemically active and can be electrochemically oxidized or reduced. Using these reactions, gas components can be distinguished and gas concentrations detected. Electrochemical gas sensors are divided into many subcategories:
(1) Primary cell gas sensors (also known as Gavoni cell gas sensors, fuel cell gas sensors, and spontaneous battery gas sensors), their principles are the same as the dry batteries we use, except that, The carbon manganese electrode of the battery is replaced by a gas electrode. Taking the oxygen detector as an example, oxygen is reduced at the cathode, and electrons flow to the anode through the ammeter, where the lead metal is oxidized. The size of the current is directly related to the concentration of oxygen. This The sensor can effectively detect oxygen, sulfur dioxide, chlorine, etc.
(2) Constant potential electrolytic cell type gas sensor. This type of sensor is very effective for detecting reducing gases. Its principle is different from that of the galvanic cell type sensor. Its electrochemical reaction occurs under forced current. It is a A true coulomb analysis sensor. This sensor has been successfully used in the detection of carbon monoxide, hydrogen sulfide, hydrogen, ammonia, hydrazine, and other gases. It is currently the mainstream sensor for toxic and harmful gas detectors.
(3) Concentration battery type gas sensor. The electrochemically active gas will spontaneously form a concentration electromotive force on both sides of the electrochemical cell. The size of the electromotive force is related to the concentration of the gas. A successful example of this kind of sensor is the automobile Oxygen sensor, solid electrolyte carbon dioxide detector.
(4) Limiting current type gas sensor. There is a sensor that measures oxygen concentration. It uses the principle that the limiting current in the electrochemical cell is related to the carrier concentration to prepare an oxygen (gas) concentration sensor. It is used for oxygen detection in automobiles and in molten steel. Oxygen concentration detection.
At present, the main suppliers of this kind of sensors are all over the world, mainly in Germany, Japan, and the United States. Recently, several European suppliers have been added: the United Kingdom, Switzerland, etc. China started very early in this field, but the industrialization process has not been effective.
