Understanding Volatile Organic Compounds (VOCs) and Emissions Control

The Environmental Protection Agency (EPA) defines a Volatile Organic Compound (VOC) as “any compound of carbon that participates in atmospheric photochemical reactions.” This definition excludes carbon monoxide, carbonic acid, ammonium carbonate, metallic carbides, and carbonates. VOCs are released into the air when certain chemicals vaporize. A compound’s boiling point indicates how easily it vaporizes: the lower the boiling point, the higher the volatility.

The EPA monitors VOC emissions from manufacturing plants and sets limits on annual releases. By understanding which types of VOCs are produced during the production process, manufacturers can select the most effective emission control system for their facility.

Types of VOCs

The EPA categorizes VOCs based on volatility. While all VOCs are considered harmful, their boiling points affect how readily they enter the air. The EPA has updated its terminology, changing the label for harmful outdoor emissions from Reactive Organic Compounds (ROGs) to VOCs.

Emission limits are not limited to outdoor air. Indoor air quality in manufacturing plants is equally important. VVOCs, VOCs, and SVOCs must be captured and destroyed to safeguard employee health. Manufacturers need to know:

  • Which types of VOCs are being released
  • Where pollutants are depositing
  • How many VOCs are being emitted

Very Volatile Organic Compounds (VVOCs)

VVOCs have a boiling point range of below 0 to 50–100°C. These highly volatile compounds often exist solely as gases. Plants using chemicals that produce VVOCs require systems capable of efficiently capturing and disposing of these emissions. Common VVOCs include:

  • Propane
  • Butane
  • Methyl chloride

Volatile Organic Compounds (VOCs)

VOCs have a boiling point range of 50–100 to 240–260°C. Although the term VOC is sometimes used broadly, it specifically refers to compounds that vaporize within this temperature range. Examples include:

  • Formaldehyde
  • D-Limonene
  • Toluene
  • Acetone
  • Ethanol (Ethyl Alcohol)
  • 2-Propanol (Isopropyl Alcohol)
  • Hexanal

Semi-Volatile Organic Compounds (SVOCs)

SVOCs have a boiling point range of 240–260 to 380–400°C. These compounds are less volatile but still require proper capture and destruction. Examples include:

  • Pesticides (DDT, Chlordane)
  • Plasticizers (Phthalates)
  • Fire retardants (PCBs, PBB)

Choosing the Right Emission Control Equipment

Selecting appropriate pollution control equipment depends on the type of VOC being released:

  • Plants with higher levels of VVOCs may have higher concentrations of airborne pollutants, as these compounds vaporize at lower temperatures. In this case, a Recuperative Thermal Oxidizer (TO) may be ideal, as it performs best with moderate to high pollution concentrations.
  • Plants emitting SVOCs may experience lower concentrations of airborne pollutants due to higher boiling points. Here, a Regenerative Thermal Oxidizer (RTO) may be more suitable, as it works well with lower pollution levels.

By understanding VOC types and their behavior, manufacturers can protect the environment, comply with EPA regulations, and maintain a safe workplace.