ForConstructionPros.com

Contract sweepers have likely heard about the Environmental Protection Agency's (EPA) emission regulations, but regulations taking effect in 2010 will have an impact on the trucks you buy and, at least in California, on the trucks you already own.

Finalized in 2001, the EPA's Highway Diesel Rule required that harmful pollutions from engines be reduced by more than 90% beginning with 2007 model year engines. For 2010, the EPA will tighten the emissions standard by requiring new diesel engines to emit no more than 0.2 grams of nitrogen oxides per horsepower-hour.

In order to comply with EPA regulations, engine manufacturers are incorporating one of two technologies in their new engines: Selective Catalytic Reduction or Exhaust Gas Recirculation. Most engine manufacturers are using Selective Catalytic Reduction technology in their engines, says Brian Giles of Elgin Sweeper.

Selective Catalytic Reduction
Selective Catalytic Reduction (SCR) is a technique for reducing nitrogen oxides (NOx) by injecting a fine mist of urea plus water through a catalyst into the engine's exhaust stream. This creates a chemical reaction turning the nitrogen oxides into nitrogen and water vapor. When heated during the SCR process the urea mix, also called diesel emission fluid or diesel exhaust fluid (DEF), turns into ammonia and carbon dioxide. These by-products, natural elements of the air we breathe, are then discharged through the tailpipe.

With SCR the nitrogen oxides reduction process takes place after combustion. Some of the benefits SCR is said to have include: enhanced thermal efficiency and fuel economy, reduction of heat rejection and cooling system stresses, and possible emissions reduction up to 90%.