Selective catalytic reduction (SCR)


The use of selective catalytic reduction (SCR) technology for reducing emissions of nitrogen oxides (NOx) in diesel engine applications is growing as emission standards like Stage 5 come into force. SCR is an effective and reliable technology that is suitable for a broad range of diesel engines and applications.

Stage 5 system layout example
Stage 3B system

How does it work?

SCR uses urea (AdBlue®/ DEF) to reduce NOx over an SCR catalyst. An SCR system consists of an SCR catalyst, urea dosing system, urea tanks, urea mixer, urea lines, various sensors and a control unit that controls the whole SCR operation. Other technologies such as DOC or DPF for reducing particulate matter (PM) can be integrated into the system, if the engine manufacturer´s chosen emission strategy requires this.

SCR and Stage 5 emission standard

The proposed Stage 5 regulations for non-road applications in the EU will require highly advanced PM and NOx emissions reduction technologies. This means that SCR technology is increasingly being used in diesel applications. Manufacturers of smaller diesel machines in particular will face a challenge with the stringent emission standards, as the lack of space is obvious, yet SCR technology requires a number of EAT system components to be fitted into a machine's design. Stage 5 exhaust systems require integrating and optimizing all components; and this is what we do best. Proventia also has ultra-compact EAT design platforms that fit even the tightest space requirements.

To comply with Stage 5, manufacturers of bigger diesel machines are expected to combine an SCR system and a diesel particulate filter (DPF). High NOx reduction targets mean that the SCR performance needs to be improved in every possible way, and this is where we can offer our best knowhow with engineering services, urea mixing expertise and thermal management skills.