Photoionization detector

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A photoionization detector or PID uses an ultraviolet (UV) lightsource to break molecules to positively charged ions that can easily be counted with a detector. Ionization occurs when a molecule absorbs high energy UV light, which excites the molecule, and results in temporary loss of a negatively charged electron and the formation of positively charged ion. The gas becomes electrically charged.

In the PID, the charged particles produce a current that is amplified and displayed on a meter as "ppm" (parts per million) or "ppb" (parts per billion). The ions recombine after passing the detector to reform their original molecules.

Typical photoionization detectors measure volatile organic compounds and other toxic gases in concentration from 1ppb to 10,000ppm. The photoionizaton detector is the most efficient and inexpensive type of gas detector. They are capable of giving instantaneous readings and monitoring continuously. They are widely used in military, industrial, and confined working facilities for safety.

PIDs are used as monitoring solutions for:

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