Drainage element and method and machine for making same
The drainage element is made with a tubular membrane that encasing a mass of discrete aggregate. The membrane being gathered together at each end thereof, is water-permeable and has a plurality of interstices characterized in being of a size for the passage of water therethrough and the filtering of fine particles of solid material from the water passing through the membrane. A short length of pipe may be fabricated into one end only of the drainage element to provide for a hook-up to a sewage system or other system.
1 . A drainage element comprising
a mass of discrete aggregate defining passageways for a flow of fluid therethrough;
a tubular membrane encasing said mass of discrete aggregate, said membrane being gathered together at each end thereof and being water-permeable and having a plurality of interstices characterized in being of a size for the passage of water therethrough and the filtering of fine particles of solid material from the water passing through said membrane; and
tie means closing around each gathered end of said membrane to retain said aggregate therein.
2 . A drainage element as set forth in claim 1 wherein said membrane has a grab tensile strength of 61/61 lbf as measured under ASTM D-5034 and a grab elongation to break in % of 45/50 as measured under ASTM D-5034.
3 . A drainage element as set forth in claim 1 where said membrane is made of spun bonded non-woven polyester.
4 . A drainage element as set forth in claim 1 wherein said membrane has at least a pair of overlapped longitudinal edges adhesively secured to each other.
5 . A drainage element as set forth in claim 1 wherein said membrane has at least a pair of sewn together longitudinal edges.
6 . A drainage element as set forth in claim 1 further comprising a pipe extending from within said mass of aggregate and beyond one end of said tubular membrane, said pipe being of a length less than the length of said tubular membrane.
7 . A drainage element as set forth in claim 5 further comprising a screen disposed over an end of said pipe within said mass of aggregate for blocking entry of said aggregate into said pipe.
8 . A drainage element as set forth in claim 5 wherein said tie means at said one end of said tubular membrane is secured about said pipe.
9 . A drainage element as set forth in claim 1 further comprising a pipe extending from within said mass of aggregate and beyond each end of said tubular membrane.
10 . A drainage element as set forth in claim 1 wherein said membrane is embossed to increase the surface area thereof.
11 . A drainage element comprising
a mass of discrete aggregate defining passageways for a flow of fluid therethrough;
a tubular membrane encasing said mass of discrete aggregate;
a pipe extending from within said mass of aggregate and beyond one end of said tubular membrane, said pipe being of a length less than the length of said tubular membrane.
tie means closing around each end of said membrane to retain said aggregate therein.
12 . A drainage element as set forth in claim 10 further comprising a screen disposed over an end of said pipe within said mass of aggregate for blocking entry of said aggregate into said pipe.
13 . A drainage element as set forth in claim 10 wherein said tie means at said one end of said tubular membrane is secured about said pipe.
14 . A drainage element as set forth in claim 10 wherein said membrane is embossed to increase the surface area thereof.
15 . A method of making a drainage element comprising the steps of forming a longitudinal strip of a membrane into a tubular cross-section about a longitudinal axis thereof with a pair of longitudinal edges disposed in overlapping relation to each other, said membrane characterized in being of a size for the passage of water therethrough and the filtering of fine particles of solid material from the water passing through said membrane;
securing said longitudinal edges together to define a tubular sleeve;
closing one end of the sleeve;
moving said sleeve along a linear path while filling said sleeve with aggregate; moving a pipe coaxially into a rear of said sleeve while continuing to fill said sleeve with aggregate; and
closing the opposite end of said sleeve about the pipe to form a drainage element.
16 . A method as set forth in claim 15 further comprising the step of placing a longitudinal bead of adhesive between said longitudinal edges of said membrane and pressing said edges together to bond said edges to each other.
17 . A method as set forth in claim 15 further comprising the step of placing a screen over an open end of said pipe prior to said step of closing one end of said sleeve.
18 . An apparatus for making a drainage element comprising
a tube for passing a flow of aggregate therethrough;
a forming collar for shaping a continuously supplied membrane strip having a pair of longitudinal edges into a sleeve about said tube with the longitudinal edges thereof in overlapping relation to receive a flow of aggregate therein;
first means for securing the overlapped edges of the strip together;
second means spaced from said tube for intermittently applying tie means about the sleeve;
third means for moving a flow of aggregate through said tube for filling the sleeve with aggregate;
fourth means for moving the sleeve from said tube during filling of the sleeve with aggregate; and
drive means for intermittently moving a pipe coaxially through said tube into a rear of the sleeve while filling the sleeve with aggregate.
19 . An apparatus as set forth in claim 18 wherein said first means adhesively secures the overlapped edges of the strip together.
20 . An apparatus as set forth in claim 19 wherein said first means includes at least one roller for pressing the overlapped edges of the strip together.
21 . An apparatus as set forth in claim 18 further comprising a cutting means for cutting through the strip and pipe.