PID lamp for gas measurement

Gas measurement is divided into two main areas:

  • Portable VOC detectors
  • Gas chromatography

In both methods, PID lamps (photoionisation detector lamps) play an important role.

PID lamp for gas measurement

PID lamps emit high-energy photons in the VUV range of the spectrum. These photons ionise any gas that has an ionisation potential lower than the photons' energy and generate positively charged ions. If ionisation takes place within the electric field between two electrodes in the sample cell, a measurable current is generated which is proportional to the concentration of the gas. PID lamps provide an efficient, inexpensive and immediately usable method for measuring volatile organic compounds (VOCs) and other gases in concentrations from the ppm to the ppb range.

Portable detectors are normally not gas-selective and determine the total concentration of VOCs. However, they can be made more selective by choosing a suitable light source.

Gas chromatography is gas-selective and more elaborate because the individual components of a gas mixture are separated in a separating column before each constituent gets into the sample cell to be detected there.