Diesel particulate trap

Apparatus for filtering solid particulates from suspension in fluid streams such as exhaust gas from diesel engines, which comprises a filter of honeycomb structure having

• a matrix of thin porous walls defining a plurality of cells extending longitudinally and mutually parallel therethrough between inlet and outlet end faces of the structure,
• the walls containing substantially uniform interconnected open porosity of a volume and size sufficient to enable the fluid to flow completely through the walls and to restrain most or all of the particulates from passing completely through the walls,
• the transverse cross-sectional shapes of the cells forming a substantially uniformly repeating pattern of geometric shapes without interior corner angles of less than 30.degree.,
• an inlet group of the cells open at the inlet end face and closed adjacent to the outlet end face,
• an outlet group of the cells closed adjacent to the inlet end face and open at the outlet end face,
• each cell of the inlet group sharing cell walls only with cells of the outlet group and
• each cell of the outlet group sharing cell walls only with cells of the inlet group,
• wherein the improvement comprises
• the volume of interconnected open porosity and the mean pore diameter of the pores forming the open porosity lying within the area defined by the boundary lines connecting points 1-2-3-4 in FIG. 4.