Why does sensor poisoning occur in gas detectors, and how can it be prevented?
1, The main cause of sensor poisoning in gas detectors
(1) High concentration gas shock
When the sensor is exposed to high concentration target gases far beyond its detection range, it may cause irreversible chemical reactions in the sensitive material of the sensor, leading to a decrease in its performance or even failure. For example, in some chemical production sites, if a gas leakage accident occurs, a large amount of toxic gas may cause damage to nearby gas detection sensors. The following are the most common harmful gases:
1. Silicides: Silicides are widely present in compounds such as lubricants, cleaning agents, adhesives, and sealants, and are widely used in industries such as petrochemicals. Organic silicon decomposes catalysts in high-temperature environments and forms solid substances on the catalyst surface, reducing sensor sensitivity. High concentrations of organic silicon compounds can immediately damage gas detectors, and can significantly suppress sensor response at concentrations of parts per million.
2. Sulfides: As by-products in the petroleum and petrochemical, leather, papermaking, and food processing industries, they are widely present in industrial wastewater and exhaust gases. Moreover, sulfides have strong alkalinity and are prone to corrode instruments and pipelines. Therefore, detecting sulfides in wastewater and exhaust gas is of great significance. Due to its high sensitivity and portability, gas detectors are an important means of in-situ detection of sulfides on site. However, high concentrations of sulfides can easily cause poisoning of electrochemical sensors.
(2) Affected by water vapor
Excessive water vapor can affect the performance of sensors and even lead to poisoning. On the one hand, water vapor may condense on the surface of the sensor, forming a water film that hinders the contact between the target gas and the sensor's sensitive material, prolonging the sensor's response time and reducing sensitivity. On the other hand, water vapor may undergo chemical reactions with certain sensitive materials, damaging their structure and properties. For example, in some humid environments such as sewage treatment plants, mines, etc., the water vapor content is high. If the sensor of the gas detector does not have good waterproof measures, it is easy to be affected by water vapor and poisoned.
(3) Dust pollution in the tested environment
Dust particles in the environment may adsorb onto the surface of the sensor, covering the sensitive area of the sensor and hindering the contact between gas and sensitive materials, resulting in a decrease in the sensitivity of the sensor. In addition, some dust particles may have corrosive or catalytic properties, which can react chemically with the sensitive materials of the sensor, thereby poisoning the sensor. For example, in some places with high dust such as mines and construction sites, effective dust prevention measures need to be taken for the sensors of gas detectors, otherwise they are easily affected by dust pollution and their performance may be affected.
2, Preventive measures for gas detector sensor poisoning
(1) Avoid contact with toxic substances
Do not use gaskets, seals, and insulation components containing silicone rubber, synthetic rubber, or sealants; Do not use silicon-based polishing agents, cleaning agents, and lubricants in environments where instruments are assembled and stored; Avoid using lubricants containing silicides for components such as gas transmission pipeline valves; Do not use adhesives containing silicides and self-adhesive labels on the surface of the instrument; Installation and maintenance personnel should not use cosmetics containing silicone oil components.
(2) Correct installation and use
Correctly select the installation location of the gas detector and avoid exposing the sensor probe to environments with irritating substances. Choose a gas detector with an appropriate range according to the actual situation, and try to avoid the sensor working for a long time in a high concentration environment of leaked gas as much as possible. Reduce the exposure time of sensors to toxic gases in the environment, and turn off the instrument when not in use.
(3) Regular maintenance and calibration
Strictly follow the installation and maintenance guidelines of the instrument, regularly maintain and calibrate the gas detector to ensure its normal operation. After exposure to highly toxic gases, clean the sampling pump, replace the gas circuit and gasket.
