Nozzleless underdrain for granular filtration system

A self-supporting underdrain in a liquid filtration system, comprising:

• primary body means including a plurality of longitudinally extending side walls and an upper wall extending therebetween defining at least in part a chamber for guiding an effluent to an outlet during a filtering operation and a backwash fluid from a fluid source during a cleaning operation;
• secondary body means connected to said primary body means and having an interior wall in common with a side wall of said primary body means for defining a secondary chamber communicating via a plurality of orifices with said primary chamber, said orifices being disposed in said common wall of said primary body means and said secondary body means, said secondary body means being provided with a plurality of spaced slots in an exterior wall different from sand spaced from said common wall to enable backwash fluid entering said secondary chamber from said primary chamber to exit said secondary chamber to a filter-medium-containing space overlying the underdrain member in the liquid filtration system;
• and
• attachment means for attaching said primary body means to a floor surface including a first flange and a second flange, said first flange defining a recess for matingly receiving the second flange of another underdrain in the filtration system.

A self-supporting underdrain member for use in a liquid filtration system, comprising:

• a main body having a plurality of walls defining at least in part an elongate primary chamber having a first volume for guiding an effluent to an outlet during a filtering operation and a backwash fluid from a fluid source during a cleaning operation;
• attachment means for attaching said main body to a floor surface including a first flange and a second flange, said first flange defining a recess for matingly receiving the second flange of another underdrain in the filtration system;
• and
• closure means connected to the side of said main body for defining along at least one of said walls a secondary chamber having a second volume substantially smaller than said first volume,
• said one of said walls being provided with a plurality of first orifices to enable communication between said primary chamber and said secondary chamber, said closure means being provided with a plurality of second orifices to enable communication between said secondary chamber and a filter-medium-containing space overlying the underdrain member in the liquid filtration system.

A self-supporting underdrain member for use in a liquid filtration system, comprising:

• a main body including a pair of longitudinally extending inclined walls, a pair of generally triangular transverse walls connecting said inclined walls to one another, said inclined walls each being provided with a pair of longitudinally extending recesses and a plurality of orifices communicating with each of said recesses;
• attachment means including a pair of flanges connected to said inclined walls for attaching said main body to a floor surface so that said inclined walls, said transverse walls and the floor surface define a cross-sectionally triangular chamber;
• and
• two pairs of elongate cover plates attached to said inclined walls over said recesses to form in each of said inclined walls a pair of longitudinally extending plenums, each of said cover plates being provided with a plurality of spaced slots.

A self-supporting underdrain member for use in a liquid filtration system, comprising:

• a main body including a plurality of walls defining at least in part a chamber for guiding an effluent to an outlet during a filtering operation and a backwash fluid from a fluid source during a cleaning operation, at least one of said walls being provided with a recess;
• a cover plate attached to said one of said walls over said recess to form a plenum at such wall, said one of said walls being formed with a plurality of first orifices to establish communication between said chamber and said plenum, said cover plate being provided with a plurality of second orifices to establish communication between said plenum and a filter-medium-containing space overlying the underdrain member in the liquid filtration system;
• and
• means for attaching said main body to a floor surface including a first flange and a second flange, said first flange defining a recess for matingly receiving the second flange of another underdrain in the filtration system.

A self-supporting underdrain in a liquid filtration system, comprising:

• primary body means including a plurality of walls defining at least in part a chamber for guiding an effluent to an outlet during a filtering operation and a backwash fluid from a fluid source during a cleaning operation;
• secondary body means connected to said primary body means for defining a secondary chamber communicating via a plurality of orifices with said primary chamber, said orifices being disposed in said common wall of said primary body means and said secondary body means, said secondary body means being provided with a plurality of spaced slots in a second wall different from and spaced from said first wall to enable backwash fluid entering said secondary chamber from said primary chamber to exit said secondary chamber to a filter-medium-containing space overlying the underdrain member in the liquid filtration system;
• and
• means for attaching said primary body means to a floor surface including a first flange and a second flange, said first flange defining a recess for matingly receiving the second flange of another underdrain in the filtration system.

A self-supporting underdrain member for use in a liquid filtration system, comprising:

• a main body having a plurality of walls defining at least in part an elongate primary chamber having a first volume for guiding an effluent to an outlet during a filtering operation and a backwash fluid from a fluid source during a cleaning operation;
• closure means connected to said main body for defining along at least one of said walls a secondary chamber having a second volume substantially smaller than said first volume,
• said one of said walls being provided with a plurality of first orifices to enable communication between said primary chamber and said secondary chamber, said closure means being provided with a plurality of second orifices to enable communication between said secondary chamber and a filter-medium-containing space overlying the underdrain member in the liquid filtration system;
• and
• means for attaching said main body to a floor surface including a first flange and a second flange, said first flange defining a recess for matingly receiving the second flange of another underdrain in the filtration system.