Photoionization Detectors (PID)

Description

Working Principle:

1. UV Radiation: A UV lamp within the PID emits photons with sufficient energy to ionize certain organic molecules.   
2. Ionization: When a molecule within the ionization chamber absorbs a UV photon with energy exceeding its ionization energy, an electron is ejected, creating a positively charged ion and a free electron.   
3. Current Generation: The generated ions and electrons are collected by electrodes within the chamber, producing a small electrical current.   
4. Signal Amplification: The current is amplified and processed by electronics, and the resulting signal is displayed as a concentration reading.  

Key Characteristics:

• Sensitivity: PIDs can detect a wide range of organic compounds, including volatile organic compounds (VOCs) such as benzene, toluene, and xylene.  
• Specificity: While not as specific as some other gas detectors, PIDs can differentiate between organic and inorganic compounds.
• Portability: Many PID instruments are compact and portable, making them suitable for field use. 
• Real-time Monitoring: PIDs provide real-time measurements of VOC concentrations.

Applications:

• Industrial Hygiene: Monitoring workplace air quality for the presence of hazardous VOCs.
• Environmental Monitoring: Detecting and quantifying VOCs in air and soil samples.

• Leak Detection: Locating leaks in industrial processes and pipelines.

• Indoor Air Quality Assessment: Evaluating indoor air quality in homes and buildings.