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From simple operational explanations to cost target and future projects, Pierce has compiled a comprehensive question and answer guide that addresses many of the SCR and Detroit Diesel DD13 questions.
What is SCR?
Selective Catalytic Reduction (SCR) is a technology that injects a urea agent (DEF) into the exhaust stream by way of a catalyst positioned downstream of the Diesel Particulate Filter (DPF). The urea initiates a chemical reaction that converts NOx into harmless nitrogen and water, which is then expelled through the tailpipe.
How does SCR technology work?
SCR requires a tank to hold the urea solution (DEF), a small pump and a catalytic device downstream of the diesel particulate filter. The tank will be sized based on usage requirements and fuel tank size, generally allowing 2-3 fuel fill-ups before needing to fill the urea tank.
Where will I buy Diesel Exhaust Fluid (DEF)?
Ample distribution of urea agent in North America will be a certainty.
Many truck stops are already well along in their preparations to supply the urea solution through either pump stations or containers. DEF will also be available in bulk containers for use at municipal refueling depots.
How will this impact the cost of fire apparatus?
While it’s still too early to provide a specific cost, industry experts have estimated the initial SCR system costs to range from $5,000 to $15,000.
Is there a freezing problem with the DEF?
Urea begins to take on a slushy consistency at 12 degrees Fahrenheit, so holding tanks and lines will be equipped with heating devices for cold climate operations. If the DEF does freeze during shutdown, start up and normal operation of the vehicle will not be inhibited and the heating system will return the DEF to liquid form. It should be noted trucks are currently operating in the Arctic with SCR and DEF.
Why did the engine manufacturers choose SCR?
Optimizing engine performance favors the production of higher levels of NOx. SCR, in turn, reduces NOx after it exits the engine, which allows the engine to run better, stay cooler and last longer. Manufacturers using SCR are able to optimize engine performance, with increased hp ratings and 3%-5% better fuel economy.
I have heard of another engine manufacturer that will not use SCR. How will they meet the new emission requirements?
An alternative technology that will be utilized is to reduce NOx in the engine cylinder. This in-cylinder approach will utilize Excessive Exhaust Gas Recirculation (EEGR) technology. EEGR relies on the engine itself to reduce the emissions level prior to the exhaust gases exiting the engine by keeping cylinder temperatures lower. This technology significantly increases the amount of heat that has to be pulled from the engine, and it may compromise vehicle performance. Lower hp/liter ratings and fuel economy are likely.
Is SCR a new technology?
Cummins and Detroit Diesel have been producing engines since 2006 that utilize SCR technology. Widespread in Europe, over 500,000 heavy trucks already use SCR technology.
I have heard regulations will require the engine to shut down if the urea tank is empty. Is this true?
Since vehicles could continue to function normally without the urea agent, the EPA will require manufacturers to ensure some method of user compliance in the use of urea. At this time, there is no definitive ruling on how this will be accomplished; however, shutting down the engine is not being considered. Pierce is currently working with industry organizations as well as the EPA to jointly develop a fire and emergency vehicle solution.
What will my choices be for 2010 engines?
Pierce will be offering fire departments the choice of either the Detroit Diesel or Cummins brands of engines.
Can you tell me more about Detroit Diesel?
Pierce, along with Detroit Diesel, will be offering the new Detroit Diesel DD13, a smaller version of Detroit’s DD15 engine. It is an in-line 6 configuration that displaces 12.8 liters. The DD13 has an extremely wide peak torque range (up to 500 RPM wide), an engine brake which offers up to 546 braking horsepower, a robust rear gear train and a ribbed cast-iron block to lower noise and vibration harshness. The DD13 boasts the longest scheduled maintenance intervals in its class, a maintenance-free crankcase breather and a B50 life of 1 million miles. Peak horsepower rating for fire apparatus applications will be 500 bhp with a peak torque rating of 1,650 lb-ft. The DD13 will utilize SCR technology to meet the stringent 2010 EPA diesel emission regulations. More information can be found at DetroitDiesel.com/engines/dd13.
Tell me more about Cummins.
Pierce, along with Cummins, will be offering the new ISX11.9, which is a smaller version of Cummins ISX15. The ISX11.9 is an in-line 6 configuration that displaces 11.9 liters. Peak horsepower rating for fire apparatus applications will be 500 bhp with a peak torque rating of 1650 lb-ft.
In addition to the ISX 11.9, Cummins will offer the popular ISL 9 liter medium range engine. Peak horsepower rating for fire apparatus applications will increase to 450 bhp with a peak torque rating of 1,200 lb-ft.
Both of the Cummins engines will utilize SCR technology to meet 2010 EPA diesel emission regulations.
More information on Cummins’ approach to 2010 EPA standards can be found at: everytime.cummins.com/every/misc/Technology/2010_Technology.page
Can I buy a 2010 engine now?
The Detroit Diesel DD13, Cummins ISX11.9 and Cummins ISL will be offered for sale in late 2009 and/or 2010 in Pierce® fire apparatus. Until that time, Pierce will continue to offer the popular Detroit Diesel S60, Cummins ISM and Cummins ISL.
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