What is an SCR System?
A Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that reduces tailpipe emissions of nitrogen oxides (NOx) down to near-zero levels in newer generation diesel-powered vehicles and equipment. The SCR system involves several components packaged together with other parts of the emissions control system. Each manufacturer has its variations of the type and sequencing of different components in the system.
How does an SCR System Work?
Hot emissions exit the engine and enter the SCR system, where aqueous urea, also known as diesel exhaust fluid (DEF) is sprayed onto a special catalyst. The DEF causes a chemical reaction in the exhaust that transforms nitrogen oxides into nitrogen, water, and trace amounts of carbon dioxide (CO2), all of which are natural components of the air we breathe. The exhaust is also routed through a particulate filter somewhere in the system before exiting through the vehicle exhaust pipe.
SCR technology is designed in such a way that nitrogen oxide (NOx) reduction reactions can occur in an oxidising environment. It is called “selective” because it reduces NOx levels within a catalyst system by using ammonia as a reductant. The chemical reaction is known as “reduction,” and the DEF acts as the reducing agent. It also converting the pollutants into nitrogen, water, and trace amounts of CO2. In the exhaust stream, the DEF is rapidly degraded to produce oxidising ammonia.
Why is an SCR important?
SCR technology is among the most cost-effective and fuel-efficient innovations for nearly eliminating diesel engine emissions. It can reduce NOx emissions by up to 90% while also lowering HC and CO emissions by 50-90 per cent and PM emissions by 30-50 per cent. SCR systems can also be combined with a diesel particulate filter to reduce PM emissions even further.
Is DPF part of SCR?
SCR and Diesel Particulate Filter (DPF) are frequently combined because they reduce both gaseous and particulate emissions (by 70% or more) and allow the most stringent (future) emission legislation to be met. SCR and DPF frequently work well together, resulting in increased SCR efficiency. One of the technical options is “SCR on DPF technology,” in which the DPF part also functions as an SCR catalyst. This could result in a more compact configuration.
But, what do you do if your DPF begins to fail? A DPF can impair a vehicle’s performance. At some point, all DPFs will need to be deep-cleaned, which includes emptying any clogged soil and dirt that has accumulated inside. Alternatively, replacing the compartment could be an option. But what about getting rid of the DPF entirely? A DPF delete kit will remove the DPF and reconfigure the computer system without it. While many kits are available, any DPF removal requires two major components: the exhaust and the tuner. The exhaust is used to physically replace the DPF while the tuner disables the vehicle’s regeneration mode and ensures that no additional engine codes appear.
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Our specialists at ECU Flash have years of experience remapping engines, speed limiters, and DPF removal. Our experts fully understand the regulations prohibiting the removal of these parts, ensuring that all procedures are legal. Fill out our online form for more information or to schedule a date for us to remap your ECU. A member of our team will contact you shortly to see how we can assist you. We can also be found on Facebook.
