Found in almost all types of industrial complexes, volatile organic compounds (VOC) are hazardous substances that can cause nerve and kidney damage to workers who are accidentally exposed to them while on the job. Due to the serious problems that can result from even low-level exposure, companies are now installing VOC detectors that can quickly detect when compounds are present in measurable quantities.
To make sure you get the most bang for your buck, it’s important to understand how VOC detectors work. Let’s take a closer look at VOC detection for industrial safety.
The most common detection technique used by VOC monitors designed for industrial safety is “photoionization”, and a sensor that uses photoionization is called a “Photoionization Detector”, or “PID” for short. These PID detectors depend on the fact that complex VOC compounds can be ionized by photons of ultraviolet light. Ionization is the process whereby a loosely-held electron is knocked out of the VOC molecule; this electron can be detected and measured by an electronic circuit. The more molecules there are, the more free electrons are generated by the UV light, and the higher the VOC reading.
Similar to combustible gas sensors, the most common PID sensors are broad-spectrum devices, meaning they detect any VOC molecules present in the air. For example, if both Benzene and Toluene are present, the detector will show a combined reading, but will not be able to distinguish between the two compounds.
Fortunately, PID sensors do offer a way to filter out some unwanted compounds. Each compound has a unique “Ionization Potential”, or “IP” value (measured in electron volts, or eV) that depends on the molecular arrangement of individual atoms. PID sensors come with different eV ratings, and can only detect compounds that have IP values below the electron-volt rating of the lamp. So if you know that the compound you want to measure has an IP value of 9.6, for example, you can use a PID sensor with a 10.0 eV rating and can be sure that you won’t detect any compounds with an IP value greater than 10.0.
Whenever the presence of a VOC is detected, it will be crucial to alert nearby personnel of impending danger. However, since all industrial facilities are different in terms of noise, layout, and other factors, doing so effectively may require a combination of both audible and visual alarm components: light and horns. To make certain personnel are notified no matter their work environment, gas detection systems that include VOC monitors can be equipped with multiple alarm systems that sound automatically in the event of an emergency. By having the ability to use strobes, horns and sirens, VOC detection systems can be installed in multiple types of work environments. From areas where equipment noise may hinder sirens to large facilities that may have personnel spread out over long distances, the right alarm station configuration can ensure everyone is notified of the danger as quickly as possible.
Finally, it is important to understand the potential VOCs that may be present and design a calibration procedure that ensures that the detector will sound an alarm when even the most insensitive gas component is present. Since PID detectors are broad-spectrum devices and will respond to multiple VOCs if present, choosing the right detector and calibration gas is critical to personnel safety.
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