def glossary

DEF Glossary

Diesel exhaust fluid commonly referred to as DEF, is relatively easy to use on a practical level. However, there are many aspects of its creation and handling that are quite complex. To help interested parties understand the full scope of DEF and its industry impact, Blue Network has collected a glossary of important terms.

Agencies and Organizations

Due to its nature, DEF must be handled with extreme care. To ensure this, professional organizations set standards. Government agencies overseeing environmental protection may also influence the use of DEF.

California Air Resources Board (CARB)

This board develops emissions regulations on the types and amounts of pollutants that can be generated by vehicles, businesses, and other sources. Only California has the authority to do this; other states aren’t allowed to develop their own regulations. Instead, they’re required to either adhere to CARB requirements or federal standards. Typically, CARB standards are stricter than federal.

Environmental Protection Agency (EPA)

The EPA is a federal agency that creates and enforces regulations that protect the environment. This includes vehicle emission standards. Before U.S. car manufacturers are allowed to sell a model, they’re required to get approval from the EPA. As part of the federal government, the EPA is subject to change under different administrations, meaning that standards may shift from year to year.

Equipment and Technology

DEF is a fragile substance that can easily lose its purity if mishandled. To ensure DEF retains its quality, special equipment is used to transport and store it. Once in the vehicle, DEF interacts with a variety of elements, resulting in a chemical reaction that creates environmentally harmless emissions.


Also called Intermediate Bulk Containers, or IBCs for short, totes are containers used in the distribution and storage of DEF. They can carry 275 to 330 gallons and are the standard for liquid chemical transport.

Particulate Matter

Pollutants comprised of solid particles such as unburnt fuel are called particulate matter. Particle size can vary; particles measuring less than ten μm are considered “small.” While both large and small particles are dangerous, those considered small are even more so. This is due to the damage they can do to the lungs.


Once it’s entered the body, particulate matter can cause cardiac and respiratory issues. Fortunately, DPF units can reduce the risk of exposure.

Selective Catalytic Reduction (SCR)

SCR describes emissions after-treatment technology. It introduces an oxidation catalyst and urea into the exhaust stream to instigate a chemical reaction that turns harmful NOx into water and nitrogen. In addition to protecting public health, this technology can actually improve fuel efficiency.

On-Board Diagnostics

This electronic telemetry system keeps drivers in the loop by reporting operating parameters. Built into vehicles, it monitors the emissions control system and applies torque penalties if said vehicles don’t have DEF.

Nitrogen Oxides (NOx)

NOx is a scientific term that refers to a variety of nitrogen oxides. These are chemical compounds comprised of nitrogen and oxygen atoms. While there are many, the two most concerning are nitrogen dioxide (NO2) and nitric oxide (NO). When they combine with naturally occurring chemicals in the atmosphere, they can create smog or acid rain.

ISO 22241

ISO 22241 describes the international quality standard for DEF distribution, production, and storage. There are five parts:


  • Handling guidelines
  • Materials
  • Quality
  • Contamination
  • Urea concentration


The full guidelines are published by the International Organization for Standardization.

Exhaust Gas Recirculation (EGR)

This technology cools exhaust and returns it to the engine inlet. As a result, the combustion temperature lowers, and there are fewer emissions.


Blue Network Services

Here at Blue Network, we’re dedicated to providing the highest quality DEF at affordable prices. Whether you need delivery or accessories, we can help. For more information, give us a call at 888-732-6668 or contact us online.

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