PIPE ASSEM. 7S6284 - Caterpillar

Engine: 3406 (S/N: 90U1-UP) 3412C (S/N: 81Z1-UP) 3456 (S/N: BGA1-UP; 9BZ1-UP) 3508 (S/N: 8TL1-UP; 3LS1-UP; 23Z1-UP; 70Z1-UP) 3508B (S/N: 4GM1-UP; 6PN1-UP; 2HW1-UP) 3512 (S/N: 3MS1-UP; 24Z1-UP; 67Z1-UP) 3512B (S/N: FFG1-UP; 6WN1-UP; 4DR1-UP; 4AW1-UP; 5AW1-UP) 3516 (S/N: 7KM1-UP; 2TS1-UP; 3JS1-UP; 3NS1-UP; 25Z1-UP; 73Z1-UP) 3516B (S/N: TAK1-UP; 6HN1-UP; 7RN1-UP; 1NW1-UP; 2JW1-UP; CCX1-UP)Introduction
Do not perform any procedure in this Special Instruction until you read this information and you understand this information.A Diesel Particulate Filter (DPF) is a filtration system for the exhaust of diesel engines that is designed to reduce the following emissions: particulates, carbon monoxide and hydrocarbons.
Illustration 1 g01156460
Cross section of the exhaust gases through the DPFThe cross section of the DPF has a honeycomb pattern. The honeycomb pattern of the cylinder forms channels that extend from one face to the other face of the DPF. The end of every other channel is plugged on one face of the DPF. On the opposite end of the DPF, the other half of the channels are plugged. Therefore, every channel is plugged on only one end. In the exhaust pipe, the exhaust must flow into the open channels and flow through the walls of the channel of the ceramic DPF in order to exit the opposite end of the DPF.The walls of the channel contain a coating of catalyst. As the exhaust gas contacts the catalyst, a chemical reaction occurs. The carbon monoxide is oxidized into carbon dioxide, and the hydrocarbons are oxidized into water and carbon dioxide. The walls of the channel also capture the solid particulate matter. Particulate collection occurs continuously while the engine is operating. As the sites of particulate collection within the DPF become filled, back pressure increases. The particulates are periodically removed through a process that is called regeneration. Once the temperature of the exhaust is equal to or is greater than 300 °C (572 °F) for thirty percent of the duty cycle, the catalyst will interact with the collected particulates to burn the particulates into carbon dioxide and water vapor. The carbon dioxide and the water vapor pass through the DPF and the capacity for the particulate collection is restored.The process of regeneration and the durability of the DPF are dependent upon the following conditions: exhaust temperature, fuel sulfur content, oil consumption and oil quality.Exhaust Temperature - Exhaust temperatures that are greater than 300 °C (572 °F) will keep the filter performing properly. Exhaust temperature does not need to be above 300 °C (572 °F) at all times, but the DPF will not regenerate below this temperature. The DPF will continually collect particulates. If no regeneration occurs, back pressure will continue to increase and the DPF will eventually plug.Fuel Sulfur - Ultra-low sulfur diesel fuel must be used. Ultra-low sulfur diesel must have a maximum sulfur content that does not exceed 15 parts per million (ppm). The use of a fuel with a higher sulfur content causes an increase in sulfate particulates due to the oxidation of SO2 to SO3. Higher sulfate levels increase the temperature for