Facts about SCR

MYTH: DEF is a toxic material that degrades in heat and cold.

FACT: Degradation won’t be a problem with safe, nontoxic DEF.

DEF is a benign, noncorrosive, nonhazardous, nontoxic, nonpolluting and nonflammable solution of 32.5 percent urea and deionized water. It’s already widely used in industry and agriculture. DEF does not become toxic at any temperature.

SCR has been used in Europe for years, in climates very similar to those in North America, yet degradation has not been an issue. During very low temperatures, if the DEF freezes, the SCR system will quickly thaw the DEF back to its original form. Normal operation will not be disturbed.  

Like any automotive fluid, DEF will degrade during long periods of disuse. But even taking into consideration the typical period of bus inactivity during summer vacation, degradation won’t be a problem.

MYTH: The big, complicated SCR system will add a huge amount of weight to the bus.

FACT: Even with 10 gallons of DEF on board, we’ll weigh the same as, if not less than, our competitor.

A leading proponent of Exhaust Gas Recirculation (EGR) claims that there is no payload penalty with its system, but our math suggests otherwise. The Cummins ISB, the engine used on the vast majority of Blue Bird’s buses, weighs 1150 pounds. The Diesel Particulate Filter adds an additional 50 pounds and the SCR system weighs about 250 pounds, including 10 gallons of DEF.

According to our calculations, Blue Bird buses with the SCR system come out weighing the same as, if not less than, our competitor.*

Some have tried to position EGR as a simple solution, but what you may not have heard is that EGR will require the addition of a bigger radiator package and other hardware changes. Cummins engines will remain similar to the ones you already know, so there’ll be no need for costly, time-consuming additional training. With SCR, you can anticipate a smooth, easy transition.

Together, Blue Bird and Cummins will continue to provide reliability, low maintenance, safe operation and the lowest total cost of ownership.

*Blue Bird buses with the Cummins ISC engine weigh 1630 pounds, plus 50 for the DPF. The ISC is selected by a small portion of Blue Bird customers who prefer a larger engine.

MYTH: DEF will cause your vehicle to lose power.

FACT: As long as the DEF tank is adequately filled, your vehicle will remain as powerful as ever.

Your bus wouldn’t run properly without oil, fuel or radiator coolant. Diesel Exhaust Fluid is just as important, because SCR requires DEF to achieve near-zero emissions.

Our SCR system, the Cummins aftertreatment system, won’t change the driving performance of your vehicle in terms of pulling power, engine responsiveness, durability or dependability. DEF consumption will be approximately 2 percent of your fuel consumption, so for every 50 gallons of fuel you use, the Cummins aftertreatment system will use just one gallon of DEF.

MYTH: Not only is DEF practically a second fuel, it will be almost impossible to find.

FACT: Though DEF is no more a “second fuel” than oil or windshield wiper fluid, it will be just as available as diesel or any other fluid your vehicle needs to run.

Some EGR users claim that because the SCR-equipped vehicles require DEF to function properly, DEF should be considered a second fuel. Why, then, do they not consider oil or coolant to be second fuels? After all, vehicles require those to run properly, as well. Calling DEF a second fuel is a scare tactic, and it’s simply untrue. DEF is simply another fluid you’ll need to occasionally replenish. It’s as easy as topping off your windshield wiper fluid. In fact, you can anticipate DEF to be available in the same places as all other necessary fluids.

Commitments are in place to make DEF available in more than 1,800 locations across the United States by 2010. The major truck stop lines have already announced plans to carry DEF.  It will also be available in 2.5-gallon containers, 55-gallon drums, 275-gallon intermediate containers and in bulk. DEF should cost less than $5 per gallon and  has been quoted as low as $3.50 per gallon on a 55-gallon drum. Fleets can obtain the fluid through a Cummins dealer, truck dealer or current manufacturers and distributors of DEF.

Having marketed DEF since 2003, Cummins Filtration, a leader in filtration, coolant and chemical technology for engine-power systems, will also have DEF available through its network of 2,500 retailers and 20,000 distribution points throughout North America. The fact is, Cummins joins Volvo, Mack, Daimler and Paccar and others in adopting the SCR emissions solution. With the majority of the trucking industry on board, finding readily accessible DEF just won’t be a problem.

MYTH: SCR will be difficult to maintain, and there’s no support network in place.

FACT: The SCR system only requires replacing a single filter, and service network training has already begun.

Blue Bird-utilized Cummins engines are designed to be reliable, keeping your buses on the road, not in the shop. The SCR system will not change your current maintenance routine—your oil filter, fuel filter, coolant filter, and other scheduled maintenance will go on as usual. A DEF filter will be the only necessary addition which will only need replacing every 200,000 miles.

When your engine does need support, Cummins’ extensive network of service providers has more than 3,500 locations in North America.  Rest assured that your team will be completely prepared to maintain your 2010 engine and aftertreatment system. And as always, you’ll receive comprehensive support through your Blue Bird Dealer, in partnership with Cummins.

MYTH: DEF is toxic.

FACT: DEF does not become toxic at any temperature.  

It is a solution of 32.5 percent urea and purified water, which breaks down into common ammonia during a chemical reaction. The SCR element converts NOx and ammonia into nitrogen gas and water vapor. These harmless elements pass over a secondary catalyst to convert any leftover traces of ammonia before the exhaust leaves the system.

MYTH: Frozen DEF will make your bus unusable.

FACT: Freezing won’t destroy or even damage DEF. 

Even if it does freeze, normal start-up and operation won’t be affected because the SCR system will thaw the fluid as the bus warms up. It’s been proven, since DEF has been used successfully in extremely hot and cold regions of Europe for several years.

MYTH: DEF is hard to use. FACT: Adding nonhazardous, nonflammable DEF to your vehicle is as simple as topping off your radiator coolant or windshield wiper fluid.
MYTH: DEF degradation will be a big problem.

FACT: It hasn’t been a problem in Europe, where climates are just as extreme as those in North America. 

DEF has a shelf life of approximately one year, but even with the typical period of school bus inactivity in the summer, DEF degradation just will not be an issue.

MYTH: DEF will be hard to find.

FACT: Cummins joins major engine manufacturers Daimler, Volvo, Paccar and Mack in the use of the SCR emission solution. Since most of the truck industry is choosing the SCR solution, DEF will be readily available from fueling stations, Cummins dealers, truck dealers or current manufacturers and distributors of DEF. DEF will be available wherever oil, lubricants and fluids are sold.

For additional information about SCR, visit everytime.cummins.com.