PID (Photoionization Detector) sensorsdetect gas concentrations by ionizing the substance to be measured through the energy excitation of an ultraviolet (UV) lamp. Characterized by high sensitivity, they are widely used in the detection of volatile organic compounds (VOCs). High humidity (>90% RH) may cause water condensation on the ultraviolet lamp window, affecting readings. PID sensors are typically used in dry environments or equipped with moisture-proof designs.
When exposed to high-concentration (e.g., >1000 ppm) or high-boiling-point (e.g., oils, aldehydes, aromatic hydrocarbons) VOC environments, PID sensors may accumulate ionization byproducts or condense/adsorb non-volatile residues (e.g., silicone oil, H₂S) on the UV lamp window. This reduces UV transmittance, leading to signal attenuation, prolonged response time, and decreased sensitivity. Prolonged exposure can permanently damage the lamp source. Equipping PID sensors with pump sampling systems minimizes contaminant buildup, mitigates these effects, and extends sensor lifespan.
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