What Are Photoionization Meters?
Description and Applications.
Ionization is based upon making a gas conductive by the creation of electrically charged atoms, molecules, or electrons and the collection of these charged particles under the influence of an applied electric field.
The photoionization analyzer is a screening instrument used to measure a wide variety of organic and some inorganic compounds.
It is also useful as a leak detector. The limit of detection for most contaminants is approximately 0.1 ppm.
Calibration. The procedure for calibration involves applying the
calibration gas (typically 100 ppm isobutylene) to the instrument
and checking the reading.
Special Considerations.
The specificity of the instrument depends on the sensitivity of the detector to the substance being measured, the number of interfering compounds present, and the concentration of the substance being measured relative to any interference.
Many models now have built-in correction or correlation factors. After calibrating the unit on isobutylene, select the gas to be measured.
The instrument will automatically correct for the relative sensitivity of the gas selected. Some instruments are listed by an NRTL for hazardous locations.
Check the operating manual for specific conditions.
Maintenance.
Keeping these instruments in top operating shape means charging the battery, cleaning the ultraviolet lamp window, light source and replacing the dust filter. The exterior of the instrument can be wiped clean with a damp cloth and mild detergent if necessary.
Keep the cloth away from the sample inlet, however, and do not attempt to clean while the instrument is connected to line power.
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