CARB-Verification Makes These DPFs The Right Investment

Sept. 28, 2010


Caterpillar offers a verified, Level 3+ diesel particulate filter for rubber-tired and tracked off-road vehicles (non-Caterpillar machines included) with select Tier 1 and Tier 2 engines ranging up to 600 horsepower — double the horse-power of three of the other five passively regenerated DPFs . The Caterpillar DPF passive regeneration system requires an engine that runs at exhaust temperatures of 464 degrees Fahrenheit (240 degrees C — what Cat calls “Normal Operating Temperature”) or more at least 40 percent of the time. The Cat DPF allows the lowest temperatures among passive-regenerating VDECS. Customers will have a single point of contact for service and warranty support — Caterpillar dealers that are familiar with the equipment applications — and that can be a fairly compelling value. Pre-engineered under-hood installation options are available for some Cat machines.

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Cleaire currently has three products — one passively regenerated and two active-regeneration systems — CARB verified for off-road use. Lonestar, the passively regenerated product, is built around a modular design that adds a lean NOx reduction catalyst to the wall-flow diesel particulate filter that is common to most Level 3+ VDECS. The lean NOx catalyst makes Lonestar the only VDECS verified at Level 3+ Mark 2, adding a 40-percent NOx reduction to the 85 percent PM reduction required for Level 3 status. It is verified for use with 1996 to 2009 engines from 150 to 350 horsepower. Phoenix is Cleaire’s diesel-burning, active-regeneration system. It is conditionally verified for Tier 1 through Tier 3 engines (roughly model years 1996 to present) up to 12 liters. Skyline (formerly known as Horizon) is an electrically powered active-regeneration verified product, approved for Tier 1 through Tier 3 engines. An integrated electric heating element should be plugged in to shore power daily to process captured PM. Cleaire’s Allmetal, which is awaiting verification, is an all-stainless version of the passively regenerating Lonestar. Cleaire’s technologies are also CARB verified to Level 3 or better in its on-road packages called Longview (passive regeneration), Vista (active-regenerating diesel burner) and Horizon (active regeneration using electric power).

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DCL holds a conditional Level-3+ verification with CARB for use of its MINE-X SOOTFILTER DPF as a passive-regeneration system on rubber-tired mobile equipment. On completion of the remaining two-thirds of its durability testing, it will be eligible for full verification. The MINE-X SOOTFILTER DPF is verified for use with engines model years 1996 through 2008 rated between 175 and 300 horsepower, and certified to particulate-matter emissions levels of 0.15 grams per brake horsepower-hour or less. Engines in this size range were not required to certify PM emissions that low until 2003, when Tier 2 went into effect. Some engines certified at 0.2 g/bhp-hr. early, though, and they’re listed in the CARB-Approved Engine Families List attached to the verification executive order. Buyers looking to consolidate purchasing with fewer retrofit dealers might look into the MINE-X SOOTFILTER DPF because the passive DPF is also Level-3+ verified for use with stationary prime and emergency standby generators, pumps, and compressors up to 300 horsepower.

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ECS Purifilter

The ECS Purifilter is conditionally verified for use with off-road diesel engines with maximum power output ratings from 50 horsepower to 750 horsepower, making it the passively regenerated VDECS capable of handling the most powerful off-road engines. It is verified for use with engine model years ranging from 1996 to 2008, but compatible engines must be certified to produce no more than 0.2 grams of particulate matter per brake horsepower-hour. Some diesels certified at that PM level ahead of time, but the first off-road diesels were not required to meet that limit until 2001. Purifilter will be eligible for full verification on completion of the remaining two-thirds of its durability testing. The Combifilter from ECS is an actively regenerated (plug-in electric) DPF that works with diesels up to 12 liters displacement in rubber-tired off-road equipment. ECS is also seeking off-road verification of its Purifilter Plus, which is currently verified for on-road heavy-duty diesels. Purifilter Plus employs a passive Purifilter DPF plus a Combifilter element for active regeneration at intervals scheduled suitably (weekly, biweekly, at engine-maintenance intervals, for example) to meet specific engines’ soot-loading rate under actual operating conditions.

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ESW Canada

The ThermaCat from ESW Canada is the first mobile, off-road Level 3+ VDEC to combine a passive diesel particulate filter (DPF) with an active-regenerating diesel fuel burner (Purifilter Plus, from ECS, is a competitor still seeking CARB verification). It’s verified for engines up to 15 liters. The hybrid system is intended for vehicles working severe-duty cycles, where exhaust temperatures are low. As long as the vehicle is operated at exhaust temperatures above 500 degrees Fahrenheit (260 deg. C), ThermaCat will regenerate passively fast enough that active regeneration is not necessary. When the vehicle runs long periods with exhaust temperatures below 500 deg. F, backpressure will increase as the filter accumulates soot. Once the exhaust-gas backpressure reaches a preset value, diesel injection activates automatically during normal vehicle operation to raise the filter’s internal temperature and burn more diesel PM off the element. ThermaCat is verified to work with engines whose exhaust temperature reaches 210 deg. C just 15 percent of the time.

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The CARB verified HUSS FS-MK diesel particulate filters as Level 3+ diesel emission control systems for use with most on-road engines through 2006 model year, and most off-road diesel engines through the 2008 model year. HUSS proved to CARB that multiple FS-MK filters can be mounted in series on vehicles to accommodate diesel engines of any size and PM output level. The company claims to have applied the active, diesel-burning filters on engines up to 800 horsepower. Volvo Construction Equipment entered a strategic partnership with the Swiss aftertreatment maker, to provide diesel-exhaust retrofits for Volvo construction equipment. Various configurations of the FS-MK filters are available as Volvo-approved products through Volvo CE dealers. Huss systems are available in a similar way for Volvo’s other heavy-duty diesel brands, Volvo Trucks, Mack Trucks, Volvo Penta, and Volvo Bus for retrofits globally.

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Ninth In A Series

Diesel particulate filter (DPF) retrofits ordered before the end of this month are sure to qualify for double the horsepower credit toward particulate-matter (PM) compliance with California’s In-Use Off-Road Diesel rule. In other words, verified diesel emissions control strategies (VDECS) ordered in the next couple of weeks for two scraper engines that total 988 horsepower, for example, bank a 1,976-horsepower credit for the owner even if they aren’t installed until after the Dec. 31, 2009, double-credit deadline. Credits are applied in the first year that the contractor’s fleet does not meet fleet-average targets established by the California Air Resources Board (CARB) for off-road diesel fleets.

So it’s time for California equipment owners to get busy ordering VDECS. To qualify for the credit, retrofits must be CARB verified (see the list of CARB verified technologies). Equipment owners working in locations nationwide should be browsing the same list when considering machine rebuilds.

Cleaire’s Lonestar DPF on this 2006 Deere 6081 engine is the only Level 3+ verifi ed diesel emissions control strategy with CARB Mark 2 status (reducing NOx 40 percent in addition to PM 85 percent).

County and municipal ordinances and federal bid specifications are increasingly demanding that equipment working in badly polluted jurisdictions be fitted with the “best available control technology” (BACT) for reducing diesel emissions. And when California gets the EPA waiver it needs to fully implement its In-Use Off-Road Diesel rule, any other state can pick up and apply the same regulation. As many as 19 other states and the District of Columbia, which all contain counties that fail to attain air quality meeting the EPA minimum standards, are moving toward implementing the CARB rule. Construction-equipment owners in those states will have to use VDECS on equipment they want to keep.

The Environmental Protection Agency is deferring to CARB in determining acceptable emissions-control equipment. EPA automatically lists VDECS as EPA-verified (see the list of EPA verified diesel retrofit technologies). There are more products on EPA’s list of verified diesel-emissions technologies, but the slim pickings available on the CARB Level-3-verified list are your only sure bets to comply across the broadest range of in-use diesel reduction efforts that you might encounter around the country.

The in-use diesel rule offers no compliance credit for applications of Level 2 VDECS (50-percent reduction in PM emissions) until all of a fleet’s engines five years old or older have been retrofit with Level 3 VDECS (85-percent reduction in PM emissions), if compatible Level 3 devices are available.

The range of engines for which there is a verified filter technology is narrow. Tier 1 engines produce so much soot that they challenge exhaust-filter reliability. Unregulated engines built before Tier 1 went into effect in 1996 typically must be upgraded before they can work with a DPF.

Diesel particulate filters are typically cylindrical elements of a high-tech ceramic such as silicium carbide in a steel sleeve. Diesel particulates catch on the porous ceramic walls as exhaust passes through. A diesel oxidation catalyst — a honeycombed structure coated with catalyst that generates heat when exposed to exhaust — upstream from the filter burns away accumulated soot, maintaining reasonable backpressure. The process is called passive regeneration. The assembled DPF typically looks like, and produces the effect of, a large muffler.

Verifications come loaded with qualifiers stipulating the kinds of engines for which VDECS are suited, the conditions under which they will regenerate, the type of machines on which engines can be mounted (rubber tired, track mounted, or steel wheeled).

Passive VDECS for mobile off-road applications are all verified with minimum-exhaust-temperature conditions necessary for them to work. To determine if an engine can be retrofit with a passive-regenerating device, its exhaust temperature must be measured in various operating conditions with a thermocouple linked to a data recorder. The engine has to run hot enough, long enough for reliable passive regeneration.

In the ideal world, all VDECS would regenerate passively, with no need for additional energy or supporting systems. Unfortunately, there are many engines whose exhaust temperatures are too cool for reliable passive regeneration.

Three of the five passive VDECS on the market are only suitable for engines up to 300 horsepower. Caterpillar has verified its passive DPF in applications up to 600 horsepower, and the ECS Purifilter is conditionally verified up to 750 horsepower. None of the passive-regenerating VDECS can work with engines that produce more than 0.2 grams of PM per brake horsepower-hour.

Active regeneration systems supply extra energy in the form of diesel fuel or electricity to clean DPFs. Electronic systems in on-road trucks, for example, monitor exhaust back pressure and begin injecting fuel as necessary. Small amounts of diesel (3 to 10 ounces per regeneration) mist a catalyst, which heats up to burn off PM accumulated on the filter.

Active systems have no minimum-temperature requirements, but they do not dramatically extend the range of engine families for which there are compatible exhaust retrofits. And they add complexity to the machine. Concerns about proper installation, durability, and being caught between the engine manufacturer and the VDECS maker in service and warranty disputes can be discouraging.

Three of the four active-regeneration VDECS for mobile off-road equipment apply only to engines of up to 12 or 15 liters of displacement — two of those are suitable only for engines made after 1995. The ECS Combifilter specifies no engine-model-year limits, and applies to engines up to 12 liters displacement. The HUSS FS-MK filters — active-regeneration diesel burners — are verified for engines with no size or age limits.

Independent Construction, from Concord, Calif., has fit scrapers with banks of three or more HUSS VDECS. The active-regenerating filters are verified for multiple installations in series with virtually any diesel engine. Of course, there are practical limits to how many filters an owner wants to maintain. To keep the scrapers’ PM production down to manageable levels, and to upgrade the machines’ reliability, Independent has repowered most of these scrapers with Tier 2 engines (supported by state grant funding).

Fuel-burning active VDECS can work without interrupting the machine’s productivity. They are attractive for rental fleets that demand reliability with no operator intervention in a wide range of operating conditions.

Electrical active-regeneration systems must be attached to shore power to regenerate. The vehicle can’t work while it is plugged in, so the option is primarily for equipment operating in central locations such as in quarries, refuse transfer, airports and warehouses or material yards.

Independent Construction repowered several scrapers to improve reliability. Cleaner exhaust allowed the scrapersto be fit with banks of HUSS VDECS to assure compliance with CARB diesel emissions rules and preserve the scrapers’ place in the California fl eet as long as necessary to extract their considerable frame value.

Model years mentioned in verification documents are guidelines rather than rules. Each VDECS is actually verified to work with engines certified to specific maximum PM rates. With every verification, there is a document that lists acceptable engine families for use with the device.

Successfully using VDECS inevitably comes down to making educated choices and working with reliable vendors. There are some obvious choices. Caterpillar, for example, has verified its own passive DPF for mobile off-road applications. Cat products come with Cat dealer support and one-stop warranty accountability.

Other indications of VDECS-maker staying power include OEM partnerships. For example, in 2008 Cat named CleanAIR an allied vendor of exhaust retrofit products specifically for stationary diesel engines. This kind of partnership is likely to give the maker volume and experience that will help them meet the demands of many applications.

Similarly, Volvo has named the HUSS FS-MK Series a Volvo-approved product. Volvo has worked with HUSS to match engines and applications — both off-road and on — to HUSS products. The VDECS can be purchased through Volvo CE and the various Volvo truck brands’ (Volvo, Volvo Penta, Mack) dealers.

All the makers of VDECS, because they’ve gone to the trouble and expense of having technologies verified, are committed to the market for the long haul.

New emissions-retrofit devices continue to be added to the verified list. If you don’t have to retrofit machines now, it may be worth waiting to see what new products are verified in the coming months. Don’t hold out false hope, though — it is unlikely that a simple retrofit solution for engines made long before 1996 is forthcoming.

Most pre-Tier-2 engines (2002 or earlier, up to 299 horsepower) will have to be gone from California in the next seven or eight years. The BACT ordinances — like those in New York City and the Chicago area’s Cook County — will effectively start pushing pre-2003 off-road diesels out of their jurisdictions.

The Big Apple requires emissions-retrofits now, and Cook County’s diesel pollution ordinance will start requiring them soon. Keep an eye on the CARB Level 3 Verified Technology list, and start planning fleet investments now. Waiting until the last minute to try to comply will be devastating for most construction equipment users.

Level 3 Off-Road-Vehicle VDECS
    Engine Compatibility        
    Size Model Years Applications Regeneration Exhaust Temp Required
CARB verifies that Level 3 verified diesel emissions control strategies (VDECS) reduce exhaust particulates by 85 percent or more, and that they will continue to do so reliably for reasonable the life of the device. Conditionally verified technologies have proven to reduce PM by 85 percent and have consistently performed for at least one-third of the required test hours. They’re considered the same as Level 3 devices, but must achieve full verification within three years.

Click here to see a similar table that includes application parameters for on-road and stationary off-road, Level 3 VDECS
Caterpillar Diesel Particulate Filter 175 - 600 hp 1996 - 2005 Off-road: rubber-tired and tracked passive 240°C - 40% of the time
Cleaire Lonestar 150 - 350 hp 1996 - 2009 Off-road: rubber-tired passive 260°C - 70% of the time
Cleaire Phoenix up to 12 liters 1996 - 2009 Off-road: rubber-tired (conditionally verified) active (diesel burner) none
Cleaire Skyline <=15 liters 1996 - 2007 Off-road: rubber-tired active (electric plug-in) none
DCL Int’l Mine-X SootFilter DPF 175 - 300 hp 1996 - 2008 Off-road: rubber-tired (conditionally verified) passive 350°C - 30% of the time
ECS Purifilter 50 - 750 hp 1996 - 2008 Off-road: rubber-tired (conditionally verified) passive 320°C - 25% of the time
ECS Combifilter <=12 liters pre 2008 Off-road: rubber-tired active (electric plug-in) none
ESW ThermaCat 175 - 300 hp 1996 - 2009 Off-road: rubber-tired and tracked active (diesel burner) 210°C - 15% of the time
HUSS FS-MK DPFs no limit pre 2009 Off-road: rubber-tired and tracked active (diesel burner) none