Article Archive
Coming Clean
Engine manufacturers opt out of the emergency services market in the face of new, more stringent EPA emissions standards being phased in by 2010
Volume 23, No. 5

engineLegend states that Henry Ford once said his Model T was available in any color the public wanted - as long as it was black. Something similar can be said for the choices that fire chiefs will have in fire truck engines beginning in 2010.

You can have any engine you want as long as it is Cummins. Behind this radical market constriction are new EPA emissions standards being phased in by 2010.

Caterpillar and Detroit Diesel have chosen to pull out of the emergency services market and the over-the-road truck market as well, said fire truck consultant Robert Barraclough. Mercedes, which owns Detroit Diesel and Freightliner, is eliminating its Series 60 engines rather than make them compatible with the new 2010 standards.

"Mercedes will have alternate engines, probably coming from Germany or Brazil for their over-the-road trucks - but only theirs," Barraclough said. "A new engine is being built by Detroit Diesel in addition to those from Germany and Brazil but, again, I understand they will only be available in Freightliner products."

Mack has engines capable of being certified to the 2010 requirements but so far has been uninterested in manufacturing "vocational" engines that could be sold to others for custom chassis, Barraclough said. Only Cummins has announced its intention to remain available for commercial and custom chassis.

Engine changes to fire trucks imposed by new Environmental Protection Agency emissions regulations beginning in 2007 have been essentially invisible to the end user so far. The same will not be true once the complete set of regulations take effect in 2010, said Donald Frazeur, Los Angeles City Fire Department division commander in charge of supply and maintenance for 1,200 vehicles.

"What we don't know is how the fire apparatus industry is going to incorporate these requirements into their designs," Frazeur said. "It is going to have an impact on the engine doghouse and the ability to provide the cooling that's required. So you're seeing design changes as we speak."

Frazeur serves as chairman of the National Fire Protection Association's Fire Department Apparatus Committee. New NFPA requirements dealing with exhaust issues stemming from the EPA standards are under consideration.

As of 2007, the use of diesel particulate filters (DPF) on diesel engines has been mandated by EPA to lower emissions as the first step in phasing in tougher emissions standards by 2010. An ultra-low-sulfur diesel fuel must be used with this device. With the sulfur content in diesel reduced from 500 parts per million to 15 parts per million, the use of this fuel presents a variety of problems for engine manufacturers.

Finding room to add the DPF is hard enough. By 2010, secondary catalytic reduction (SCR) emission systems will be mandated on most chassis, making further serious demands for space. For example, SCR systems require a supplementary tank with urea, an organic compound that fights nitrogen oxide emissions when injected into a vehicle's exhaust.

"A urea tank is fairly common in Europe," Barraclough said. "They've been meeting standards similar to these for a long time."

The moment engineers add more complexity and hardware to the truck, it means encroaching somewhere else on the vehicle, he said.

"Right now, the size of the primary DPF has encroached into the pump area and underneath the cab, both in space and in heat," Barraclough said.

For chassis manufacturers, the trick is finding an efficient way to configure the exhaust system. Unfortunately, the new EPA regulations frown upon extensive exhaust modifications.

"The fire truck manufacturers used to be able to move exhaust whenever it got in the way of anything," Barraclough said. "They'd just cut and splice and get it done. You can't do that anymore. Once you get a chassis that has an exhaust system you're probably going to have to leave it right where it is."

In a recent issue of the Darley Times newsletter, W.S. Darley Co. Vice President for Engineering Mike Ruthy said that a SCR system would encroach on the Darley pump house and may be problematic for other brands of pumps.

"It will take up a lot of extra space, but I hear Cummins has a 'design-around' solution that accommodates midship pumps," he said.

Darley midship pumps have a narrow gear box because of its vertical gear alignment, meaning less trouble fitting new exhaust systems, he said. CAFS (compressed air foam systems) may need to be reconfigured to accommodate the exhaust, but it would merely be a matter of mirroring the current design of the driver's side instead of the passenger's side.

PTO (power take off) driven pumps will be harder to work around, Ruthy said. Unless chassis manufacturers change to the 3000 EVS transmission with the top mounted PTO, options may be limited.

"That said, I cannot say that any chassis manufacturer has laid down a clear and firm direction, so I expect some future surprises," Ruthy said.

The simple fix would seem to be vertical exhaust, but that presents its own problems under special circumstances, Frazeur said. For instance, what if the truck is parked under a canopy?

"Rather than just say 'route it up vertically,' I think we have to keep the exhaust within a certain temperature," he said.

The combustion-ignition cycle of an engine involves a fixed mass of air being acted upon. A basic four-stroke diesel cycle consists of combustion being replaced by heat added to the air. Exhaust is then replaced by a heat rejection process that restores the air to its initial state.

The 2007 EPA standards have increased total heat rejection between five and 30 percent, depending on the engine make, model and power rating. Exhaust gas temperatures can rise to 1,200 degrees Fahrenheit downstream of the DPF. However, NFPA 1901 standards effective in 2009 limit tailpipe gas to 851 degrees F.

"NFPA is coming down with added requirements to deal with some of the changes in design, particularly with the DPF," Frazeur said. "It's not so much where you put it but exhaust temperatures are going to be a lot higher. We're going to have to regulate these temperatures so that we're not driving around starting grass fires."

One temperature issue of concern to firefighters is emissions control by steady state burn off of particulates. When the emissions system reaches a certain level of particulates, the exhaust flow reverses to burn them out. Under the right circumstances, this burn off can constitute a fire danger during emergency operations. Emissions controls will slow or shut down the engine when a certain level of emissions is sensed to allow the burn off, potentially affecting pump pressure at a critical moment.

"An override on the burn off is one of the things we are specifying," Frazeur said. "The engine doesn't automatically go into burn off. The operator has the ability to override if you're in a bad spot, such as pumping at a scene and you've got grass up against the exhaust."

Requiring an override for fire trucks may mean obtaining a special exception from the EPA, he said.

"The EPA has not shown a willingness to allow us that," Frazeur said.

Dealing with the heat problem is going to mean a bigger radiator, among other things. To gain the space for that added equipment is probably going to mean a redesign of the cab interior. But updates such as SCBA integrated into special seats built to crash standards make that redesign difficult.

Giving up the custom chassis in favor of a return to commercial chassis for fire trucks is a possibility, Frazeur said. Some tough tradeoffs would have to be made regarding available space.

"The problem with those apparatus is that they're made for over-the-road truckers, not firefighters," Frazeur said. "There are design issues regarding durability and access in an emergency."

The most immediate impact is expected to be larger emergency vehicles in the future, he said. The cost of the engines to pull these bigger trucks will probably range between $25,000 and $30,000.

"It looks to me like it is going to impact our apparatus, especially ambulances," Frazeur said. "It looks like our apparatus is going to grow one to two feet longer."

 
 

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