For emission compliance, all MACK chassis are equipped with a DPF unit which is designed to reduce soot-related emis- sions, particularly on vehicles used in metropolitan areas. The DPF unit replaces the standard muffler. The outer skin of the DPF unit reaches a temperature of approximately 300 °C (572 °F), and exhaust outlet temperatures can reach approximately 700 °C (1,290 °F), during regeneration cycles. Outlet temperatures may be lowered as much as 250 °C (480 °F), measured 152.4 mm (6 in) from the outlet, by the installation of an exhaust gas diffuser.
Vehicle upfitters must evaluate the effect these elevated temperatures can have on the equipment being installed, as well as the impact of any exhaust system modifications that may be performed. Sufficient clearance (approximately 152.4 mm [6 in] minimum) away from the DPF unit must be maintained for any tempera- ture-sensitive components such as hydraulic lines, air lines, wire harnesses, electronic control units (ECUs), etc. If sufficient clearance cannot be maintained, shields must be installed to prevent heat-related damage to any temperature-sensitive components. On the DPF unit, the areas around the clamps are the hottest.
Shields should be installed around the clamps to provide protection for any heat-sensitive components that may be located in close proximity to the DPF clamps. Exhaust system modifications, including modification or removal of an exhaust gas diffuser, can result in heat-related dam- age to vehicle equipment or other property. Vehicle upfitters are responsible for any damage due to exhaust system modifica- tion or removal. In addition to maintaining proper clearances for any heat-sensitive components, the exhaust stack outlet must be positioned in such a way to prevent rain ingestion. W7031929 Fig. 2 Allow Sufficient Clearance (A) Between Body Installation and DPF A.
152.4 mm (6 in) Minimum DPF Surface Temperatures The DPF unit is equipped with heat insulation that covers most areas of the DPF. Uninsulated areas of the DPF are at the clamp areas, body connections, inlet pipe and outlet pipe. The following surface temperatures have been measured with the DPF freely positioned in a room temperature environment with no forced cooling or wind; only self convection. Note: The temperatures provided are not maximum temperatures. The surface temperature in certain vehicle applications is dependent on the degree of encapsulation and the airflow around the DPF unit.
During aftertreatment DPF regeneration, exhaust gases exiting the DPF outlet can reach temperatures as high as 700°C (1,290°F). In cases where a heated dump body is being installed on a platform truck, or modifications are being made to the vehicle exhaust system to accommodate a heated dump trailer, vehicle upfitters must evaluate the effect these elevated tem- peratures can have on the body, as well as the impact that modifications to the exhaust system can have on the vehicle. Mack Body Builder Instructions PI / CHU, AN / CXU, GR / GU, TD, LR, TE / MRU USA141023213 Date 2.2018 Body Builder; Engine, MP7, MP8, and MP10 Page 21 (40) All Rights Reserved