Tier 4 Final requirements are achieved with SCR technique

In 2014, Volvo Penta released its full line of Tier 4 Final compliant industrial engines. But what exactly are Tier 4 Final requirements, and what do they mean to the customers? In this blog post, I will focus on how Volvo Penta achieves Tier 4 Final requirements by using the SCR technique, and how the technique benefits both our customers and the environment.  


A regulation of exhaust emissions led to a revolution in engine technology

In the 1990s, the US, Japan and the European Union passed legislation regulating the exhaust emissions from off-road vehicles. Since then, a revolution has been underway in engine technology, yielding a range of exciting new engine designs and innovations. The laws have come into effect over the years in stringent phases, called ‘tiers’ in the US and ‘stages’ in Europe. In 2014, the legislation entered its most rigorous phase. All off-road engines with output over 75 kW in the US, and 130 kW in the EU had to meet Tier 4 Final requirements, which reduced NOx and PM emissions by 99% over pre-legislation levels.

One should not underestimate the importance of lower emissions

The legislation regulates several kinds of harmful exhaust emissions, including nitrous oxides (NOx) and particulate matter (PM). The importance of lowering NOx and PM levels cannot be underestimated. Particulate matter are shown as black soot and smoke, and besides creating an unpleasant odour, they can cause lung irritation and, in some cases, cancer and heart diseases. Nitrous oxides, on the other hand, are responsible for creating acid rain, as well as produce ground-level ozone and smog.

Improved selective catalytic reduction technology

In the process of eliminating these two harmful substances, there is an unfortunate trade-off; whenever NOx are decreased, PM will increase, and while PM levels get lower, NOx levels will rise. Volvo Penta’s solution was to improve the selective catalytic reduction (SCR) technology, that the company had already implemented in its Tier 4 Final engine generation. With the SCR technology, AdBlue™ is injected into the exhaust line, it reacts with NOx in the catalytic converter and turn the harmful compound into nitrogen and water.

DPF system – a costly alternative with a negative impact on the environment  

Many of Volvo Penta’s competitors have configured their base engines’ combustion rate to produce low levels of NOx but emit high levels of PM. Their solution was to add a diesel particulate filter (DPF), which captures the soot and periodically incinerates it down to harmless ash in a process called regeneration. Though effective, this approach has its own drawbacks, for example high fuel consumption. Furthermore, a DPF system needs costly maintenance and must be replaced regularly. Overall, a DPF system requires many extra parts, from air pumps and compressors to ignition coils, all of which can fail or need replacing. While most engine manufacturers installed a DPF to meet Tier 4 Final requirements, Volvo Penta put all their efforts into improving the SCR technology instead.

“It would have been far easier for us to use a DPF, which was already an existing technology. And ultimately our competitors’ engines with DPFs emit the same low levels of PM and NOx as ours do. But because our Tier 4 Final engines are configured to perform at optimum levels, burn less fuel and produce very little smoke, they have ended up being a much better solution”, says David Hanngren, manager of industrial product planning at Volvo Penta.

Volvo Penta Tier 4 Final engines put the environment and our customers first

Volvo Penta put customer needs at the heart of our design process, creating a new line of powerful low-maintenance, low-emissions engines that hit the market in 2014. Volvo Penta only uses SCR in its Tier 4 Final engines, as it is a simpler, more straightforward solution for our customers, with fewer parts and less maintenance than a DPF. Another crucial part of Volvo Penta’s Tier 4 Final solution is light exhaust gas recirculation (light EGR). Because NOx are created at very high temperatures, the EGR further contributes to reducing NOx by lowering the peak combustion temperature.

“Because we believed that reducing NOx and PM emissions to Tier 4 Final levels could be achieved with just SCR, we put all our efforts into improving that technology — and making sure we didn’t need to use a DPF, which can end up being more hassle for the customers,” says David Hanngren, manager of industrial product planning at Volvo Penta.

Volvo Penta stays at the forefront by developing more innovative technologies

Our range of five new Tier 4 Final engine platforms share a common design concept, making installation easy and intuitive for OEMs that use multiple engine sizes in their products. The environment has always been a high priority for Volvo Penta. Though Tier 4 Final is a major step forward, the process of lowering emissions in off-road engines isn’t over yet, there are more stringent regulations in the pipeline for years to come. Volvo Penta is already working with innovative technologies to meet future regulations, while continuing to keep customer needs at the forefront of every new advancement we make in emissions reduction.

Do you have any questions concerning exhaust emissions from off-road vehicles, or Tier 4 Final? If so, you are welcome to contact me with any questions. Please visit our website for more information.    

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