LAND DRAIN COMPRISING A DRAINAGE CONDUIT COVERED BY A KNITTED FABRIC FILTER SLEEVE

Abstract: A land drain having a tube (11) or the like forming a drainage conduit through which water will be drained and a knitted fabric filter sleeve (12) around the drainage conduit, the fabric of the sleeve having a pile, conveniently compris­ ing terry loops (T) extending from ground stitches (G) generally radially relative to the longitudinal axis of the conduit (11), the pile surface of the fabric facilitating efficient liquid flow into the drainage conduit notwithstanding any accumulation of chemical reaction particles. The pile may be impregnated with a chemical agent or agents effective to minimize interference with drainage caused by chemical reaction particles such as ochre.

Description: LAND DRAIN COFIPRISING A DRAINAGE CONDUIT COVERED BY A KNITTED FABRIC FILTER SLEEVE Land drainage has long been accomplished through underground drainage conduits formed of tiles or tubing. Particularly in recent years, land drainage has been accomplished by the installation of flexible corrugated drainage tubing. It has long been recognized that certain soils will quickly clog such land drains unless provision is made for protecting the drain tile or tubing against intrusion of soil particles. Various filter materials have been proposed and have been developed for preventing such early blockage of a drainage line, including knitted fabric filter sleeves as described in U.S. Patents Nos. 3976578 and 4118940. It has also been discovered that certain chemical reactions occurring in soil may contribute to blockage or filling of drain lines. In particular, difficulty has occurred with a particular iron composition known in the land drainage industry as ocher or ochre. While the filter arrangements currently in use within the land drainage industry successfully deal with intrusion by fine soil particles, difficulty has upon occasion been encountered with ocher and with other similar chemical reaction related particles which may accumulate on filter surfaces or within drainage lines. It is an object of the present invention to provide a knitted fabric filter sleeve and the combination of such a filter sleeve with a land drainage conduit which is capable of enhanced filtration capabilities under difficult circumstances such as the presence of chemical reaction particles. To this end, the present invention is characterized in that a knitted pile fabric is employed for the filter sleeve, the pile surface of the fabric facilitating efficient liquid flow into the drainage conduit notwithstanding any accumulation of chemical reaction particles. A further object of the present invention is to provide a drainage conduit and a filter sleeve for the conduit which facilitates the inclusion, in such a combination, of chemical compounds effective to neutralize or minimize the interference with drainage caused by chemical reaction particles such as ocher. In accordance with this feature of the invention, the pile portion of the knit fabric filter sleeve contemplated by the present invention is impregnated with a suitable chemical agent or agents for counteracting anticipated chemical reaction particle intrusions. Brief Description of Drawing Figure 1 is an elevation view-, partly broken away, of a drain tube and filter sleeve in accordance with one embodiment of the present invention; Figure 2 is a section, taken generally along the line 2-2 in Figure 1 and showing the filter material of the present invention as installed about a drainage tube; Figure 3 is a schematic perspective view of a knit fabric forming the filter in the drain line of Figures 1 and 2; Figure 4 is a partial perspective view of a portion of the fabric, viewed from the exterior of the drain line as shown in Figures 1 and 2; and Figure 5 is a view similar to Figure 4, as viewed from the inside of the drain line of Figures 1 and 2. Referring to the accompanying drawing, a drain line is shown (in Figures 1 and 2) which bears substantial similarity to a drain line illustrated and described in United States patent 3,976,578. In the particular form illustrated, the drain line includes a corrugated, flexible drainage pipe or tube 11 and a knit fabric filter sleeve 12 extending over the outer surface of the tube 11* As will be appreciated by persons knowledgeable in the land drainage art, the drain line of the present invention may incorporate flexible corrugated drainage tubing made of plastic material (as illustrated in Figures 1 and 2) or may incorporate "hard tiles" made of clay, concrete, or other materials and formed in relatively short lengths. The present invention contemplates that a land drain may use a conduit of either type, notwithstanding the specific illustration of a flexible corrugated drainage tube 11 in Figures 1 and 2. The filter sleeve 12 used in the drain line of the present invention comprises knitted pile fabric, preferably terry loop fabric mounted with the loop pile directed radially inwardly toward the longitudinal axis of the enclosed tubing 11 or tile. More particularly, the material used as the sleeve 12 comprises synthetic multifilament yarn formed into stitches having particular characteristics. The yarn 20 (Figures 3 to 5) preferably is crimped multi-filament polyester yarn having a suitable denier which may be in a range of from about 70 to about 150. Preferably, the yarn 20 is circularly knitted into a tube of predetermined diameter and of an indeterminate continuous length of up to 300 meters. Certain of the yarns (indicated at G in Figures 3 to 5) are knitted into stitches defining a ground or base fabric, while others of the yarns (T in Figures 3 to 5) are knitted into stitches defining terry loops extending from the ground to a pre dctcrmined height of from about 1 to about 10 millimeters. The fabric is knitted in such a way that the stitches in the ground portion of the fabric define open areas of a selected micron size, preferably less than about 100 microns. By virtue of the knitting of the yarn into stitches defining both a ground and pile loops extending from the ground, the stitch structure is locked against undesirable distortion and opening of the fabric, in a manner distinct from woven fabrics. Further, the fabric is locked against runs and enhanced resistance to abrasion or tearing is imparted. As herein used, the term "pile fabric" refers to any knitted pile fabric including both terry loop and other pile constructions. I{hile it is preferred that the fabric be knit in the form of a tube having a diameter, in a relaxed condition, less than the maximum diameter of the tubing 11 so as to have an undulating surface when positioned on the tube, it will be appreciated that the fabric may be opened into a flat or web form and subsequently cut and sewn in whatever manner is necessary or appropriate to form a tube of the correct diameter. In use, the filter sleeve 12 preferably is mounted in such a way that the piles T extend radially inwardly toward the enclosed tube 11. In such an arrangement, the pile serves to somewhat separate or space the ground-portion of the knitted sleeve from the corrugations of the tube 11 while facilitating flow longitudinally of the tube from one circular drainage channel to an adjacent circular drainage channel. By such flow longitudinally of the tube 11 along the external surface thereof and between the external surface and the ground portion of the knitted fabric, blockage otherwise possibly arising from deposition of chemical reactive particles is minimized. In accordance with one contemplated feature of the present invention, a knitted filter sleeve 12 so installed may have the pile portion thereof treated with an appropriate chemical compound impregnant effectivefor resisting formation of or dissolving chemical reaction particles which might otherwise block flow through the drainage line. Additionally, the knitted tube used as the filter sleeve 12 may be everted, to be positioned on the tube 11 with the pile facing radially outwardly where direct contact between the pile and soil particles is deemed desirable or appropriate. As will be appreciated by persons familiar with the art of textile fabric impregnation, the presence of the piles T in the knitted filter sleeve 12 will substan tally enhance retention of the chemical compound impregnant deposited thereon. Such persons will further appreciate that such impregnation may be by means of liquids, pastes, powders or the like and that the chemical compound impregnant may be bound to the piles T in a number of different ways. As will be appreciated, the specific chemical compound impregnant chosen may vary with specific soil conditions. Inasmuch as the full range of soil conditions in which the filter of the present invention may be employed is not known at this time, no specific chemical compound impregnant is here suggested.

Claims: CLAIMS 1. A land drain comprising a drainage conduit (11) and a knitted fabric filter sleeve (12) covering the drainage conduit for filtering fine particles of soil from water passing through the sleeve and into the drainage conduit, characterized in that the sleeve (12) comprises a knitted pile fabric (T). 2. A land drain comprising a drainage conduit (11) and a. knitted fabric filter sleeve (12) covering the drainage conduit for filtering fine particles of soil from water passing through the sleeve and into the drainage conduit, characterized in that the knitted fabric of the sleeve (12) is formed of stitches defining a ground (G) and defining terry loops (T) extending from the ground (G) and being directed in a generally radial direction relative to the longitudinal axis of the drainage conduit (11). 3. A land drain according to claim 2, wherein said terry loops (T) extend from said ground (G) for a distance of from about 1 to about 10 millimeters. 4. A land drain according to claim 2 or 3, wherein said sleeve is circularly knitted from a synthetic multifilament yarn (20). 5. A land drain according to claim 1 2, 3 or LS, wherein said knitted fabric filter sleeve has said pile or said terry loops (T) directed radially inwardly toward said drainage conduit (11). 6. A land drain according to claim 1, 2, 3 or 4, wherein said knitted fabric filter sleeve has said pile or said terry loops (T) directed radially outwardly away from said drainage conduit (11). 7. A land drain according to any one of the preceding - claims, further comprising an impregnant present in said pile or said terry loops (T) and effective for resisting formation of chemical reaction particles.

Inventors: BEANE, FRANK THOMAS
Applicants: KNITTED SLEEVE (OVERSEAS) LTD
Application year: 1980
Main classification: E02B11
IPC codes: E02B11