DEFAdBlue

DEFAdBlue is a term sometimes used to refer to diesel exhaust fluid (DEF), commonly known under the brand AdBlue, and to the class of products used to reduce emissions from diesel engines equipped with selective catalytic reduction (SCR) systems. The phrase may denote either the generic DEF product or branded goods marketed under AdBlue or similar names by various manufacturers.

Composition and function: DEFAdBlue consists of a precise solution of urea (typically about 32.5%) in demineralized water. When injected into the exhaust stream, the urea hydrolyzes and forms ammonia, which reacts with nitrogen oxide (NOx) over an SCR catalyst to produce nitrogen and water, thereby reducing NOx emissions.

Standards and quality: In many regions, DEF products must meet ISO 22241 standards that specify purity, urea concentration, ionic content, and allowable contaminants. Quality control aims to prevent contaminants or improper concentrations that could impair SCR systems or corrode components.

Handling, storage, and safety: DEFAdBlue should be stored in dedicated, clean containers away from petroleum products and direct sunlight. It is non-flammable and has low acute toxicity, but can irritate eyes and skin and should not be ingested. The solution freezes at low temperatures (roughly -11°C) and should be thawed before use. Contamination with oils, metals, or other chemicals can impair SCR performance.

Applications and market: DEFAdBlue is used in many on-road heavy-duty vehicles, buses, and some passenger cars with SCR technology, as well as certain stationary diesel generators, to meet emissions regulations. Availability and branding vary by region; AdBlue is a widely recognized trademark in many markets, while DEF is a generic designation in others.

See also: AdBlue, diesel exhaust fluid, ISO 22241, selective catalytic reduction.