Today we will briefly and quickly introduce the difference between the catalytic combustion sensors and the electrochemical sensors used for toxic gases in combustible gases. Actually, each gas has these two characteristics. Only some gases are easier to explode, some gases are particularly toxic. Simultaneous interpreting the difference between different sensors helps us to recommend products according to the customers' use environment.

1. Introduction of catalytic combustion sensor:

The catalytic combustion gas sensor is based on the thermal effect principle of catalytic combustion, which is composed of detection element and compensation element. Under certain temperature conditions, the combustible gas will be flameless combustion under the action of the detection element carrier surface and catalyst, the carrier temperature will rise, and the platinum wire resistance inside it will rise accordingly, so that the balance bridge will lose balance, It can output stable current signal, and then through the later circuit amplification, stabilization and processing, finally display reliable value. The concentration of combustible gas can be known by measuring the change of resistance of platinum wire.

Catalytic combustion sensor is mainly used for combustible gas detection, with the advantages of good linearity of output signal, reliable index, low price and no cross infection with other non combustible gases.

This kind of sensor will be placed in a loop, and when a stable voltage is applied to both coils at the same time, they will be heated to a very high temperature. The sensor is connected to a Wheatstone bridge and a balance resistor to detect changes in coil resistance. When the combustible gas contacts the sensor, the active coil will burn off the combustible gas and cause the resistance temperature to increase, while the other reference coil will not have temperature change because it cannot burn the gas. The temperature difference leads to the difference of resistance, through which the concentration signal of combustible gas is deduced.

Combustible gas sensors are widely used in many fields. In the fixed combustible gas alarm market, they are mainly distributed in coal mines, petroleum and petrochemical fields.

2. Introduction to electrochemical sensors:

Electrochemical sensor: it is made of film electrode and electrolyte. The gas concentration signal decomposes the electrolyte into positive and negative charged ions and transmits the signal through the electrode.

Its advantages are: fast response, accuracy (can be used for ppm level), good stability, quantitative detection, but short life (more than or equal to two years). It is mainly suitable for the detection of toxic gases. At present, this type of sensor is used in most toxic gas detection in the world.

Electrochemical gas sensor is used to detect the voltage or current on the electrode to sense the type and concentration of gas (partial pressure) when the gas reacts on the electrode (including oxidation and reduction). The utility model is characterized by an electrolyte (liquid and solid) and a pair or three electrodes in contact with the electrolyte.

(1) The principle of galvanic cell gas sensor is the same as that of dry cell, but the carbon manganese electrode is replaced by gas electrode. In the case of an oxygen sensor, oxygen is reduced at the cathode and electrons flow through the ammeter to the anode, where lead is oxidized. The magnitude of the current is directly related to the concentration of oxygen. This kind of sensor can detect oxygen effectively.

(2) The principle of this sensor is different from that of the galvanic cell sensor. Its electrochemical reaction is forced by the current. It is a real Coulometric Sensor. This kind of sensor has been successfully used in the detection of carbon monoxide, hydrogen sulfide, hydrogen, ammonia, hydrazine and other gases. It is the mainstream sensor of toxic and harmful at present.

Electrochemical gas sensors are widely used in chemical, mining, military and other industries, such as safety detection, environmental monitoring, production process control, etc. This electrochemical gas sensor has the advantages of small volume, fast detection speed, accuracy, portability, direct detection and continuous detection, which is superior to the optical and spectral gas detection methods in the past. It has important practical significance for improving human living environment and protecting people's physical and mental health, so it has a good market prospect.