Photoionization detectors are portable units that detect a wide variety of gases and vapors. This type of detector works best to detect organic compounds in the surrounding area. Units usually include an ultraviolet lamp and an ionization chamber, and results are almost instant. Photoionization detectors list whether volatile organic compounds are present, but do not identify the type unless they are combined with a gas chromatograph.

Photoionization detectors are used mainly in mining, construction and environmental cleanups to analyze possible leaks or dangers to workers. There are many different models, including hand-held units and larger bulkier products.

1. Photoionization detectors aren't suitable for semi-volatile substance detection. Using them in this way can be dangerous and unreliable.

2. High humidity or water vapor can interfere with test results, causing false positives and hindering the data-collecting abilities of photoionization detectors.

3. Strong electrical fields, sudden temperature changes and high concentrations of methane can affect instrument responses.

Action Steps
The best contacts and resources to help you get it done

Find a hand-held photoionization detectors provider

Hand-held photoionization detectors usually provide only basic functions, but are the most economical and simplest method of monitoring gas and vapor problems. These models are battery powered and often rechargeable. They have a small range and provide a read-out on a screen on the device. Sometimes, these small hand-held models can be used in conjunction with a computer or station further away to provide more comprehensive monitoring.

I recommend: Find photoionization detectors at Photovac or check out the selection at SKC.

Buy a photoionization detectors system

If your needs are more complicated you should consider a deluxe model, often called a photoionization detectors system. These are larger units that may have multiple sensors and monitors, as well as a charging station and a base control. These are used most often in chemical-spill situations where the possible contamination area is large and may require several sensors. You'll find photoionization detectors information can be easily analyzed on-site with some models.

I recommend: Buy a photoionization detectors system from Geotech, or purchase one from RAE Systems.

Purchase permanent or mounted photoionization detectors

Occasionally, a site must be constantly monitored for spills or leaks and only a permanently functioning model will do. Photoionization models are available as plug-in units and alarms that will alert you if a volatile compound is sensed. This type of model is used most often in areas that require 24/7 monitoring, and are generally more expensive.

I recommend: Check out the mounted model sold by the Environmental Equipment & Supply or purchase one of Watlow's permanent models.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Always check the range of your photoionization detectors to determine how wide an area you can test at a time. Each model has a different range, which can effect how quickly and thoroughly a test can be performed on an area. Extended-range models are available if quick detection is a must.