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. As of December 2009, DEF is available at all Detroit Diesel service centers nationwide.
Does DEF have a shelf life?
Yes, as do many fluids, including gasoline and diesel fuel, DEF does have a shelf life. DEF's shelf life is dependent upon the temperature it is being stored. For example, at a constant 24/7 temperature of 77 degrees Fahrenheit (the average temperature in Atlanta, GA in July) DEF has a shelf life of 36 months.
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 $13,000 to $25,000 depending on the engine make, model, and size.
I have heard SCR will increase the wheelbase of new fire trucks. Is this true?
Pierce has been working to develop low impact packaging solutions for fire apparatus. As a result, Pierce has developed patent pending packaging solutions that will not affect wheelbase, will not impact cab space, will not impact compartment space, and will not limit options. Other than topping off the DEF fluid tank, Pierce's SCR solution will be virtually transparent to most fire departments.
Is there a freezing problem with the DEF?
Urea begins to take on a slushy consistency at 12 degrees Fahrenheit. 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 most 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. This is why over 90% of the trucks produced in North America that meet 2010 EPA standards will utilize SCR technology. This is also why over 500,000 (and growing at 25,000 per month) in Europe utilize SCR technology. *Source: www.factsaboutscr.com/performance/default.aspx
Is SCR a new technology?
Cummins and Detroit Diesel have been producing engines since 2006 that used SCR technology. Widespread in Europe, over 500,000 heavy trucks already use SCR technology. In addition, most truck manufacturers (including Kenworth, Freightliner, Mack, Volvo, Hino, Ford, GM, and Mercedes) will use SCR technology to meet the new standards. In fact, 90% of the trucks produced in North America will 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. Most engine manufacturers accomplish this by de-powering the engine only after the ignition has been turned off if the DEF is allowed to run dry. Keep in mind, the amount of DEF carried in the Pierce truck will last over four full tanks of diesel fuel. Additionally, at no time will the engine shut off or depower while running. 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 offers either Detroit Diesel or Cummins engines.
Can you tell me more about Detroit Diesel?
Pierce, along with Detroit Diesel, is 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, offers both the new ISX11.9, and the 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. The ISX 15 will have a minimum rating of 550 bhp with a peak torque rating of 1850 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 1,300 lb-ft.
All of the Cummins engines will use SCR technology to meet 2010 EPA diesel emission regulations.