A PID, or Photo-Ionization Detector, measures a broad range of volatile organic compounds and some inorganic compounds in the parts-per-million (ppm) to parts-per-billion (ppb) range. These devices are affordable, often small and come as either hand-held or wall-mounted, providing an instant reading indicating whether gas is present.
They are vital in go/no-go situations where personnel are unsure of what threats they face. These devices use ultraviolet (UV) rays to bombard gas samples and detect a broad range of VOCs such as formaldehyde, methane, and benzene, as well as hydrocarbons that typically occur in oil drilling and refining.