VOC Detection: Comprehensive Guides and Expert Advice



What are VOCs?

VOC is an acronym for Volatile Organic Compounds. These are Carbon-containing molecules that are gaseous at ambient temperatures. They are potentially dangerous to health and the environment and are found in a broad range of industries and locations.

What are typical VOCs that would need to be monitored? And where are they found?
  • Aromatics
  • BETX Compounds (Benzene, Ethyl Benzene, Toluene and Xylene), most commonly found in petrochemical, oil and gas.
  • Ketones and Aldehydes (compounds with a C=O bond)
    • E.g. Acetone, Methyl Ethyl Ketone (MEK) and Acetaldehyde, most commonly found in industrial cleaning applications.
  • Amines and Amides
    • E.g. Diethyl Amine, most frequently found in dyes and pharmaceuticals
  • Chlorinated Hydrocarbons
    • E.g. Trichloroethylene, again commonly found in industrial cleaning applications
  • Sulphur Compounds
    • E.g. Mercaptans, most commonly found in paints
  • Unsaturated Hydrocarbons
    • E.g. Butadiene, most commonly used in the production of automobile tyres
  • Alcohols
    • E.g, Ethanol, an extremely broad range of industries will use alcohols beyond the obvious
  • Saturated Hydrocarbons
    • E.g. Butane and Octane, most commonly found as an LPG source, lighters etc
Are all VOCs harmful in some way?

All VOCs have the potential to cause harm in high enough quantities or over long enough periods but the toxicity of each compound differs greatly. Exposure guidance in the UK is covered by EH40 which is a freely available document discussing Short Term Exposure Limits (STEL- 15 minutes) or over a normalised 8 hour working day Time Weighted Average (TWA). All mixtures containing VOCs should be supplied with a Material Data Sheet (MSDS) which will specify the quantity of each VOC in the mixture, along with any particular actions that should be taken if exposure occurs.

Where and when would I need to monitor VOCs?

Monitoring should never be mistaken for control. It is a method by which you can establish baseline measures and risk assessments and implement good control techniques; you can then confirm the efficacy of your control using monitoring over a short- or long-term basis. Exposure can be managed on an individual using monitoring if this is deemed to be an adequate part of control measures.

What type of VOC monitoring instruments are there?

VOC monitoring can be done in a plethora of different ways depending on risk and application. Available technologies include but are not limited to PID (Photo Ionisation Detectors), FID (Flame Ionisation Detectors), Colorimetric Gas Detection Tubes and Gas Chromatography. Selection of the correct instrumentation is very important and is determined by the requirements of your application, so please contact us for additional advice so we can help specify the right choice.

Are all VOC monitors intrinsically safe?

This depends on the measurement technology. Most PIDs (Photo Ionisation Detectors) are Zone 1 rated but there are lower-cost options which are not. FID (Flame Ionisation Detectors) and Gas Chromatographs are usually safe zone use only.

Do I need to measure ppm or ppb?

This is entirely application driven and dependent on risk. Please contact us to discuss your application in more detail.

What is the ionisation potential of a VOC?

The ionisation potential of any gas is the amount of energy required to displace an ion and therefore give it a charge which we can detect. All gases in the universe have an ionisation potential, some higher and some lower. In order to detect a gas with a PID (Photo Ionisation Detector) for example, the ionisation potential of the gas must be lower than 11.7eV (Electron Volts). As long as it is below this level the gas can be ionised and detected using PID technology. A wallchart of common VOCs is freely available from Shawcity on request.

Will Shawcity interpret the data from my VOC monitor?

We are able to download and retrieve data from an instrument for you if it has been supplied by us and requested at the outset. Unfortunately we cannot interpret results or make control recommendations. This would be the job of a consultant and we do not offer this service for data. We do, however, provide a consultative approach to identifying the correct measurement technology for you.