Primarily employed for spot gas concentration measurements, these chemical detectors comprise sealed glass tubes filled with a sensing chemical, which alters its color upon exposure to the target gas.
Fixed gas detectors are commonly installed either close to the process area within a plant or control room, or in locations which requires protection, such as underground car parks.
Usually handheld or worn on safety equipment, portable gas detectors are utilized for monitoring personnel's surroundings. These devices often emit audible and visual warnings upon hazardous level of gas detection.