Supporting Reduced Emissions

ACS Industries’LSeal technology designed to provide sealing, support for aftertreatment systems

ACS Industries has developed a variety of protective and support seals and exhaust joint seals for use on 2007 heavy-duty diesel engines.Among these is the L-Seal support system for diesel particulate filters, which is designed to create a cushion that not only accommodatesthe linear tolerance variations in the cone, shell and substrate, but is designed to deliver enough axial and radial support to support theentire system independently of other mounting elements.

Supporting Reduced Emissions - 50188 A

shas been well documented,the upcoming 2007 EPA heavy-duty on-highway emis-sions standards will be the first regula- tions that require the use of exhaust aftertreatment systems, including diesel particulate filters and diesel oxi- dation catalysts. And with significantly greater reductions mandated for 2010, it seems likely that selective catalytic reduction (SCR) — already widely used in Europe — will also become part of the emissions aftertreatment mix in North America. In the variety of DPF filters thathave been developed, filter substrate materials such as cordierite, silicon carbide (SiC), knitted wire mesh and sintered metals have been selected, based on high filter efficiency, thermal shock resistance, low space require- ments, low system mass and low thermal expansion coefficients.Asometimes overlooked aspect ofDPF design is the mounting system that holds the substrate in position within the DPF housing. In addition to conventional radial mounting, support rings, edge pins and cone modifica- tions assist in retaining and providingaxial support to the filter.But as Dr. Sivanandi Rajadurai (Raja), vice president of Exhaust Products for ACS Industries, explained, “these modifications tend to affect the linear tolerance of the system.”ACS Industries, headquartered inWoonsocket, R.I., is a global supplier of engineered knitted wire mesh tech- nologies, producing a broad range of knitted wire mesh filters, breathers, vibration isolators and liquid/gas sep- arators for automotive, heavy-duty and industrial applications. The com- pany also supplies a variety of protec- tive and support seals and exhaust joint seals designed for use on 2007 heavy-duty diesel engines.Among these is the L-Seal supportsystem for DPFs, which is designed to create a cushion that not only accommodates the linear tolerance variations in the cone, shell and sub- strate, but also deliver more than enough axial and radial support to support the entire system independ- ently of other mounting elements.During operation, DPFs encounter increased particulate loading andbackpressure, which affects the axial force exerted on the substrate. Moun- ting systems must be able to handle these and other in-use forces stem- ming from thermal, mechanical and road-load conditions. Raja noted that, due to the larger size of the sub- strates typically used on heavy-duty engines, their higher bulk densities and higher thermal expansion coeffi- cients, “conventional mounting sys- tems often fail to provide sufficient mounting pressures to hold it in place.“The L-Seal provides enough axialand radial compensating force so that either one or both can effectively hold the system,” Raja said. “It also offsets any mounting deterioration within the system due to normal wear and tear, expansion and weight loss from vibra- tion and erosion, as axial support is independent of resonance frequency.”Simple modifications to the L-Sealcan be used to alter the axial and radial mounting forces, the company said. Even minor changes in wire con- figurations yield drastic changes in L- Seal functionality. Tweaking charac-