DPF failure linked to major fire in Washington state

7 October 2011

A major forest fire in south Washington state could have been caused by a failure of a diesel particulate filter (DPF) installed on a truck traveling on Highway 97. Sparks coming of the vehicle are a suspected source of fire that started near a Greek Orthodox Monastery, 12 miles northeast of Goldendale, WA.

The fire started on September 7, 2011, and burned southeast through forested canyons and flat areas with dry grasses. The fire—mapped to cover an area of 3,600 acres (1,460 ha)—destroyed more than 100 structures, including 29 residences, according to Washington press reports. With the involvement of 721 firefighters, the fire was contained by September 18, 2011.

The suspected DPF was a LongMile filter supplied by Cleaire, who notified the California ARB about the fire. Following the incident, the ARB suspended the verification of the LongMile system, as well as its sister AllMetal DPF system for off-road vehicles.

Under the terms of the suspension letter, agreed to by Cleaire, the company will suspend sales and installations of LongMile and AllMetal systems, and recall and remove from service (1) all LongMile systems installed on EGR-equipped Cummins ISX engines, (2) all LongMile system installed on buses and (3) all AllMetal filters installed on off-road equipment. Cleaire will also inspect all other LongMile installations on EGR engines, and provide all owners and operators of LongMile and AllMetal filters with instructions on the appropriate action to take if a system backpressure warning light is illuminated.

Fleets who installed the affected filters to comply with ARB regulatory requirements will retain their credits, even if the filters are removed from the vehicle.

The LongMile and AllMetal are passively regenerated filters utilizing a diesel oxidation catalyst (DOC) positioned upstream of a sintered metal particulate filter. Both systems include a backpressure monitor and a warning light in the operator’s dashboard. The sintered metal substrate utilizes the technology developed by SWH, HJS, and (former) Purem. The sintered filter technology is used by HJS in an actively regenerated system for retrofit light-duty applications in the European market. A sintered metal filter plant, currently owned by Detroit Diesel, was also built in the Detroit area.

While the cause of the fire remains under investigation, it appears that an uncontrolled regeneration occurred in a soot overladen filter. The filter substrate, formed from a sintered metal sheet into a corrugated structure resembling an engine air cleaner, has a large void volume that can accumulate a substantial quantity of soot. If the filter becomes overladen and no action is taken (e.g., if the vehicle operator ignores the backpressure warning light), a catastrophic uncontrolled regeneration may occur. During such event, it may be possible for the hot, molten metal particles to become oxidized and to produce sparks from the exhaust pipe.

Cleaire has been one of the major suppliers of retrofit diesel emission controls in California. In July, the ARB awarded the prestigious Haagen-Smit Clean Air Award to Cleaire’s president Brad Edgar. In August, Cleaire was acquired by NewWorld Capital Group, a New York-based private equity firm.

Source: ARB | InciWeb | LandLine Magazine