Apparatus, Chassis Components

Fire Industry Today

Issue 8 and Volume 18.

By Spencer Dell,
Senior Marketing Communications Specialist,
Cummins Inc.

During the past ten years, the fire industry has seen the many changes in emissions regulations relative to on-highway diesel engines. New emissions regulations have brought on new engine technology including electronic fuel systems, exhaust gas recirculation (EGR), as well as aftertreatment technology including diesel particulate filters (DPFs) and selective catalytic reduction (SCR), which can be found on most of today’s engines. These changes in regulations and the resulting new technology developments have raised some questions on how the exhaust aftertreatment systems will impact fire and emergency vehicle operation. This article will focus on the evolution of the aftertreatment technology used by engine manufacturers in the industry and address how these systems impact the operator.


The year 2007 brought the introduction of the DPF for most in the industry. Engine manufacturers used the DPF to help clean up the particulate matter-one of the emissions pollutants regulated by the United States Environmental Protection Agency (EPA) and more commonly referred to as soot. By using the DPF in place of the traditional muffler, the engine could operate more efficiently, allowing the aftertreatment system to handle the exhaust emissions control and lowering particulate matter. With the introduction of the DPF came a term known as “regeneration.” Regeneration is the process of removing the excess soot (particulate matter) from the DPF by raising exhaust temperature. It often is performed passively while the engine is operating at a certain temperature, although some instances require the operator to manually perform a parked regeneration to clean the system. Standard in all fire and emergency vehicles with a DPF is a series of dash lamps helping to inform the driver when regeneration is required. As the DPF begins to fill with soot, these lamps will illuminate, notifying the operator that a regeneration needs to be performed. One key point to note is that in 2007, Cummins chose not to initiate a “derate,” or performance penalty, for fire and emergency vehicles as the DPF filled with soot.

2010 Regulations

In 2010, new regulations brought the emissions levels, most notably oxides of nitrogen (NOx), down to near-zero levels as particulate matter levels were already at this level in 2007. Many engine manufacturers chose to use SCR, which uses diesel exhaust fluid (DEF) to help attain these new emission levels. DEF is an additional fluid stored on the vehicle in a specifically labeled tank that the driver needs to refill when needed, much like engine coolant and windshield wiper fluid.

Keeping an adequate DEF level ensures that the engine will operate appropriately and as designed. Just like in 2007 with the introduction of the DPF, drivers are notified of a low DEF level through a series of lamps on a vehicle’s dash. Based on typical DEF usage in an emergency vehicle application, operators can expect to fill up their DEF tank roughly 10 times per year or about once every 5.5 weeks depending on the vehicle’s use. Maintaining an adequate DEF level is a simple procedure, and Cummins recommends simply topping off the fluid when filling up the diesel fuel tank.

If the DEF level reaches a critically low point on Cummins EPA 2010 engines, a performance penalty (also known as a derate) is initiated to incentivize the driver to refill the DEF tank. This derate, mandated by the EPA in 2010, is a reduction in engine power (torque) applied only when the DEF level is critically low. Cummins implemented a modification in July 2011, based on a change issued from the EPA, to alter the derate specifically for fire and emergency vehicle applications regarding critically low DEF levels. This change resulted from the Fire Apparatus Manufacturers’ Association (FAMA) approaching the EPA to propose that the current derates be adjusted specifically for fire and emergency vehicle applications. After the change from the EPA was announced, Cummins responded, and engines built after July 8, 2011, imposed a vehicle speed derate of 55 miles per hour (mph) instead of the previous engine torque derate.

More Change for 2013

In 2013, the new emissions requirements did not result in additional aftertreatment technology. Engines still feature both the DPF and SCR aftertreatment technologies. What did change for 2013 engines was relief for fire and emergency vehicles provided by a Direct Final Rule (DFR) issued by the EPA. This DFR, published in June 2012, gave engine manufacturers the flexibility to apply certain modifications to the emissions control systems that would allow emergency vehicles to be operated without reduced performance during an emergency situation. This was a voluntary opportunity for engine manufacturers to participate based on the detail within the DFR.

Cummins elected to participate and worked closely with industry organizations, chiefs associations, and Cummins customers to provide outreach and education on how our aftertreatment system works and to determine the best solution for our customers. In addition to our efforts, we chose to implement a new solution for 2013 that eliminates all performance-related derates on our 2013 fire and emergency vehicle rated engines through a new software calibration. What this means for the operator is that the in-cab warning lamps will still function to alert that the matter should be addressed at the next available opportunity, but there will not be a performance derate initiated by the engine system that could hamper the ability to respond to an emergency situation.

This new software calibration on Cummins 2013 engines is also available to customers with previous model year engines as a service calibration update. So, for example, if you have a 2010 model year Cummins engine that operates with one of the previously mentioned performance derates, you can upfit your engine with this new 2013 emergency vehicle calibration.

The many emissions regulations and the aftertreatment system technology developments over the years have raised many questions, but it is important to note that today’s products are designed to help emergency personnel respond efficiently and effectively without hampering their ability to complete a mission.

SPENCER DELL is a senior marketing communications specialist and has been with Cummins for five years. He is responsible for on-highway market communications including advertising and PR support specifically for the fire and emergency vehicle market. In addition, he is responsible for educating and consulting the North American sales and support team at Cummins.