Name a common detector used in gas monitoring.

A photoionization detector (PID) is widely recognized and utilized in gas monitoring for its ability to detect volatile organic compounds (VOCs) and other gaseous substances. The principle behind a PID involves the ionization of the gas sample when it is exposed to ultraviolet light. When the gas molecules absorb this energy, they become ionized and produce charged particles, which can then be measured to determine the presence and concentration of different gases.

PIDs are particularly valuable in industrial and environmental settings where monitoring for hazardous gases is crucial for safety and compliance. Their sensitivity to a broad range of organic compounds makes them a preferred choice for many applications, such as air quality monitoring, leak detection, and occupational health assessments.

Other detectors mentioned are designed for different purposes. Radiation detectors are mainly used for identifying radioactive materials, thermal imaging detectors are used for detecting heat emissions for applications such as surveillance or building inspections, and motion detectors are primarily utilized for security systems to sense movement. These differences highlight why the photoionization detector stands out in the context of gas monitoring.