The article starts by explaining what EGR (exhaust gas recirculation), DOC (diesel oxidation catalyst), DPF (diesel particulate filter), and SCR (selective catalytic reduction) systems are. It defines them as follows:
“EGR is a design function of the engine that introduces inert exhaust gas to the combustion chamber to act as a filler. This lowers combustion pressure and heat for a reduction in oxides of nitrogen emissions (NOx).
SCR further diminishes NOx though the injection of DEF (diesel exhaust fluid), which is a specific mix of urea and water.
DOC is employed to reduce carbon monoxide and hydrocarbon emissions along with sulphur-based exhaust particulates. In simple terms, this is known as diesel soot. The soot then enters the DPF where it is stored and burned off at an elevated temperature. This converts the soot to ash. The conversion takes places in the DPF with heat that is generated in the DOC during a process called regeneration.
The DPF is nothing more than a trap as you would place in a cornfield to determine moth population. If you never emptied that trap, it would fill up and become useless. Cleaning a DPF is emptying the trap (often the DPF is identified as a soot trap in literature) since it can only hold so much ash.”
The article discusses that while regeneration is often relied on for cleaning these systems. There are both active and passive regeneration. Passive regeneration can take anywhere from 20 to 40 minutes and active regeneration can take upwards of one hour or longer. During these procedures the truck or farm machine must be parked and not in use. Unfortunately, passive regeneration is not typical on trucks or equipment exposed to short duty-cycle or light load service. Whichever option you have on your engine they will need to be removed and properly cleaned.
As the article states, “The procedure for cleaning either the DOC or DPF involves four pieces of dedicated equipment. It begins with an airflow test and weighing of the components. This is followed by a mechanical cleaning with air pressure and a dedicated tool, a check of the matrix’s integrity with a lightbox, baking the components in an application-specific oven at 1,000°F. for approximately 12 hours with a computer controlled cool-down rate, and a second flow test.”
Enviromotive is the industry leader in diesel particulate filter cleaning equipment and have a highly trained staff that can answer your questions about these systems and the proper cleaning techniques to follow to keep your equipment running as efficiently and clean as possible. Please fill out the contact form below if you are interested in learning more or contact us today by calling 800-954-8265. We have the best informed DPF related technical support available in the industry. We look forward to hearing from you!