Engelhard Corp.’s DPX catalytic particulate filter has been approved for inclusion in the U.S. Environmental Protection Agency’s Voluntary Diesel Retrofit Program.

The DPX filter is approved for use in all on-highway, 4-stroke heavy-duty diesel engines in combination with ultra low-sulfur diesel fuel (less than 30 ppm).
The approval means that states will be able to claim state implementation plan (SIP) credits for retrofitting heavy-duty diesels with DPX filters. EPA established the Voluntary Diesel Retrofit Program to create an incentive for states to begin cleaning up diesel pollution immediately, even though new federal emission standards for diesel engines will not begin to take effect for some time.
Under the program, state air quality planners can work with fleets to choose verified technologies that will reduce emissions from the diesel vehicles in their fleets. States determine the amount of SIP credits to which they are entitled based upon the pollution-control technologies implemented. A list of potential funding sources is available from EPA to help allay the costs associated with diesel retrofits.
The credit allowed for retrofitting with the DPX filter will be a 60% reduction in particulate matter, carbon monoxide and hydrocarbon emissions; however, actual reductions are typically greater than 80% for CO and HC and greater than 90% for particulate matter.
Engelhard’s DPX filter uses a patented catalytic technology to continuously burn particulates at normal diesel operating exhaust temperatures and convert it to carbon dioxide and water.
The filter also reduce emissions of carbon monoxide and hydrocarbons including polyaromatic hydrocarbons and other pollutants classified as toxic. They feature a simple design for easy installation and are made of stainless steel to promote long service life. DPX filters offer low pressure-drop, which minimizes backpressure.