VOCs: How detecting Combustible Gases is Different from Toxic Gases
Posted in: Gas Detection


Gas detection is a serious topic for many businesses. Although there are many different types of gases out there they generally fall into only a few groups. There are two very basic groups of gases. The first are toxic gases which will kill you if you breathe them in. The second is combustible gases (VOCs) which could explode if certain criteria are met.
There is a lot of overlap between these two categories as many different gases are both combustible and toxic. However the method of detecting them is very different.
With toxic gas the amount of each gas is important. A less than LC50 (Lethal Concentration to 50% of people) dose of carbon monoxide with a less than LC50 dose of chlorine is still less than an LC50 level of gas. Because of this it is important that you measure each gas individually to ensure worker safety.

All About VOCs

Combustible gases are typically, though not always, also volatile organic compounds (VOC). A VOC is defined as an organic chemical which has a high vapour pressure at room temperature. This high pressure results in a low boiling point, and this makes them explosive.

Unlike toxic gases, it doesn’t matter which VOCs are present. You can detect VOCs together with a Photo Ionic Detector (PID) which displays the Lower Explosive Limit (LEL) of all the gases in the area.

The LEL is the lowest possible concentration of VOCs before an explosion is possible. It does not mean that an explosion will happen as there are a variety of factors to get an explosion. This includes having an ignition source.

At the other end of the spectrum from the LEL you have the Upper Explosive Limit (UEL), over which there is too much gas for an explosion to occur. Because of the toxic nature of many VOCs this number is not as common.

For more information about how to detect VOCs and other combustible gases as well as information about the equipment used to detect them please reach out to us at Concept Controls toll free at 1-800-793-9548.

December 10, 2020
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