A Guide for Fleet Managers on SCR Technology

  • Industry News
  • BlueDEF
  • July 20, 2020

The Environmental Protection Agency, OEMs and many trucking fleets have committed themselves to a cleaner environment by reducing NOx (oxides of nitrogen). To reduce NOx emissions that are harmful to the environment and public health, most new diesel-powered engines are equipped with a Selective Catalytic Reduction (SCR) system.

What is SCR and what does this growing technology mean for your fleet?


SCR is an after-treatment emissions control technology that uses a urea based diesel exhaust fluid (DEF) and a SCR Catalyst to significantly reduce NOx emissions. SCR is currently used by almost all OEM manufacturers and its adoption across industries utilizing heavy-duty engines is projected to grow — it is predicted that more than 3 million DEF-equipped Class 1-3 vehicles will be on the road in 2016 and more than 5.1 million will be driven by 2018. Most diesel-powered on-road vehicles produced since 2010 utilize SCR technology, including heavy-duty trucks, diesel pick-ups, delivery vans and European luxury cars. In addition, diesel-powered off-road equipment such as agricultural and construction equipment has been required to use SCR technology since 2014.


What are the benefits to utilizing SCR technology?


SCR technology does not change the design or operation of the engine, but does allow manufacturers to tune engines to boost performance, increase engine reliability and achieve fuel savings.


Engines equipped with SCR are able to function at optimal combustion temperatures, which increases fuel efficiency and contributes to the production of engine power. One of the greatest benefits fleet managers recognize with SCR technology is the cost savings associated with increased fuel efficiency. Post 2010 heavy-duty trucks can achieve fuel savings of around 5% compared to 2007 models with similar engine specifications; off-road machines with SCR also report fuel savings of 5% and higher.


SCR also results in longer overall engine life, as there is a reduced dependency on exhaust gas recirculation (EGR), less heat rejection and greater component reliability.


How does SCR work?


To treat the harmful NOx exhaust that is released from diesel engines, SCR systems inject small quantities of diesel exhaust fluid (DEF) into the exhaust upstream of a catalyst, where it vaporizes and decomposes to form ammonia and carbon dioxide. In conjunction with the SCR catalyst, ammonia (NH3) converts NOx to harmless nitrogen (N2) and water (H2O).


DEF is injected into the exhaust stream only as required. It is a non-toxic mixture of high purity synthetic automotive grade urea and deionized water. It is not a diesel additive and is stored independently in a dedicated tank.


How do I maintain my SCR system?


  • Monitor DEF levels to avoid running out of DEF. EPA 2010 requirements dictate that diesel engines stop running when they run out of DEF, but most vehicles are equipped with easy-to-read gauges that clearly illustrate DEF levels. If the level becomes too low, an alert will let the driver know the DEF level must be replenished. If the driver runs out completely the vehicle power will be reduced to encourage the operator to refill the DEF tank. Once the DEF tank is refilled, normal power levels will be restored on the vehicle. All major truck stops, dealers and distributors carry DEF and PEAK Commercial & Industrial, the nation’s leading supplier DEF, provides an online locator to help drivers locate a nearby BlueDEF retailer.
  • Change the DEF filter every 200,000 miles or 6,500 operating hours. The DEF filter is very important to long-term SCR functionality as it removes urea crystals and other contaminants picked up during storage and handling. Replacement of this filter is the only periodic maintenance tactic required on SCR engines in addition to regular diesel engine upkeep and takes only a few minutes.
  • Use high-quality DEF. SCR systems are extremely sensitive to chemical impurities in the urea solution. With SCR system replacements costing more than $10,000, it is critical that pure, high-quality DEF is used at every refill. Purity is critical to ensuring proper function — just one teaspoon of salt can contaminate 5,000 gallons of DEF. PEAK Commercial & Industrial’s BlueDEF conducts batch testing with every blend to assure the product’s quality and give fleet managers and drivers peace of mind that their engines are prepared to perform at peak levels.
  • Maintain proper DEF storage and handling equipment. Utilizing proper equipment, including storage drums, tanks, pumps and dispensers, throughout DEF distribution protects the product’s integrity and avoids equipment failure. DEF is corrosive to copper, brass, and aluminum as well as carbon steel; only approved materials as listed in the ISO 22241 standards should be used in contact with DEF.
  • Inspect the tank for any signs of contamination during normal maintenance schedules. Contamination may be visible through debris in the tank or discoloration of the fluid. If these signs occur, the fluid should be disposed of in accordance with local ordinances and the tank must be thoroughly cleaned with distilled water. Once the tank is drained completely, it should be refilled with new DEF fluid. Using high-quality DEF products like PEAK Commercial & Industrial’s BlueDEF whose patented, closed-end delivery system ensures product purity and approved equipment will help avoid tank contamination and promote optimal SCR function.


SCR technology has been proven as a beneficial, cost-effective way to comply with EPA regulations, increase fuel efficiency and reduce a fleet’s environmental impact. SCR systems do not require any additional driver training, as drivers need only to read the DEF gauge and fill the tank with high-quality fluids. The growth in SCR systems ensures that drivers will be able to locate DEF at truck stops nationwide to keep your fleet moving cleanly and efficiently for years to come.


Originally posted on Trucking Info and Work Truck