Home > Facts About SCR

What is SCR?                                                           

Selective Catalytic Reduction (SCR) is one of the most cost-effective and fuel-efficient diesel engine emissions control technologies available. For passenger cars and light duty trucks, the ability to meet strict emissions and fuel efficiency guidelines affordably without compromising driving power and performance is attractive. In the commercial trucking industry, including heavy and medium duty trucks, the ability to reduce emissions to near-zero levels while also delivering a 3-5% diesel fuel savings distinguishes SCR as one of the only emissions control technologies that is as good for business as it is for the environment.

Did you know?  According to an online study conducted in May 2009, more than half (51.2%) of truck buyers are likely or very likely to consider the purchase of SCR to meet the 2010 EPA standards, compared to only 31.2% that are likely or very likely to consider increased EGR.  Find out more by clicking here.

Click here for interviews with industry experts, who will tell you about the importance of SCR in their own words.


How Selective Catalytic Reduction Technology Works

SCR technology is designed to permit nitrogen oxide (NOx) reduction reactions to take place in an oxidizing atmosphere. It is called "selective" because it reduces levels of NOx using ammonia as a reductant within a catalyst system. The reducing agent reacts with NOx to convert the pollutants into nitrogen, water and tiny amounts of carbon dioxide (CO2) - natural elements common to the air we breathe everyday. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid, which can be rapidly hydrolyzed to produce the oxidizing ammonia in the exhaust stream. SCR technology alone can achieve NOx reductions in excess of 90%.

What is SCR?

Some companies say that SCR will take up needed space "back of cab" - leading SCR advocates disagree. In fact, Detroit Diesel developed an evolutionary 1-Box BlueTec SCR system that integrates emissions control technology into one optimized and compact unit. For more information, click here.

Selective Catalytic Reduction Facts vs. Fiction

"SCR will take up needed space 'back of cab'" - leading SCR advocates disagree. Click here for information on Detroit Diesel's 1-Box BlueTec SCR system.

SPECIAL REPORT: Response to CARB Letter to Health Effects Institute

A Blatant Misrepresentation  (The World Trucks Blog)

April 2009 - DEF Fact or Fiction?

EXCLUSIVE REPORT: Cat out of the bag?

SPECIAL REPORT: Toxicity Claim is False-Urea is less harmful than ammonia

SPECIAL REPORT: Response to OOIDA Request for EPA Delay


North American Selective Catalytic Reduction Technologies

Heavy- and medium-duty truck and engine manufacturers in North America are adopting SCR to meet EPA 2010 emissions standards. The following are examples of companies that are incorporating SCR into their product portfolios for 2010:

Detroit Diesel BlueTec System   Detroit Diesel's SCR technology solution to meet 2010 emissions standards. Detroit Diesel is engineering its continuing product line of HDEP engines, like the new DD15, to be BlueTec-ready.

Volvo SCR

Mack SCR

Cummins check out the Fleetguard Diesel Exhaust Fluid Usage Calculator


Hino Trucks

Isuzu Commerical Trucks

National Railway Equipment Co.


Mid-America Trucking Show:


DEF for 2010: Diesel Exhaust Fluid Supply Stream is Stocked & Ready

- Click to find out more about the Educational Exhibit at Mid-America Truck Show

DiscoverDEF.com: North America's first stop for DEF

- Click to find out more about this new premier DEF locator service