DEF Off-highway

As the term might already imply the off-highway sector consist of all equipment which is not allowed on the highway, this means this type of machinery almost never leaves its operating area. We can divide the equipment family into several industries such as agriculture, mining, forestry and construction. Each industry has a different breakdown in regards to powerband depending on the sort of labour involved and as a result has different emission limits.

We have highlighted the powerbands and some examples below:

  • kW < 19                   commercial mowers, mobile welders
  • 19 ≤ kW < 56           bulldozers, forklifts, agricultural tractors
  • 56 ≤ kW < 130         tractors, backhoes, excavators
  • 130 ≤ kW < 560       tractors, combines, road graders
  • kW > 560                 off-highway trucks, crawlers

Off-highway equipment started using Selective Catalytic Reduction (SCR) technology in North America in 2007 and as a result of the direct link between SCR and Diesel Exhaust Fluid (DEF), started consuming DEF. It wasn't until the end of the Tier 4 Interim phase-in at the start of 2012, when more stringent NOx limits became law, that manufacturers started adopting SCR technology more widespread. Besides the higher NOx converting rate in comparison to Exhaust Gas-Recirculation (EGR), SCR technology also showed to improve fuel savings. This is an indirect effect as a result of the engine being allowed to operate at optimal conditions. In short, the fuel savings are a direct result of an engine being allowed to operate at optimal fuel burning conditions and producing higher volumes of NOx. The hazardous NOx gasses are broken down into nitrogen and water by use of SCR and DEF.

With the recent introduction of Tier 4 Final we see the SCR market really starting to gain momentum in both Canada and the U.S.A. and as a result increase DEF consumption. Many manufacturers have now incorporated SCR technology either as a standalone after-treatment option or in combination with EGR.

The Canadian off-highway emissions standards are in-line with U.S. EPA legislation and as a result a similar market development can be observed in both countries.