Filtration of particles from water entering tubular drain - by surrounding drain with circular sleeve of knitted synthetic cloth

摘要

Soil particles 100 mu are filtered from water entering a tubular drain by a sleeve of knitted cloth. The tubular drain is flexible and is undulating with peaks alternating with hollows in the longitudinal direction, the hollows having holes for the water to pass through. A sleeve made of a cloth of extensible, creped synthetic threads covers the tube. The sleeve is knitted with a dia. smaller than that of the tube so that when it is pulled over the tube it stretches to form undulations corresp. to the hollows in the tube and is continually under tension. The sleeve is knitted using a stitch that makes the cloth ladderproof and prevents it becoming unknitted. Sleeves of knitted cloth are made in lengths of =50 m. to fit over drains of the same length. Particles =100 mu, in size are filtered out by the cloth sleeve, but those of =25 mu pass through into the tubular drain. Used for filtering fine silts and soil particles from water entering field drains. Filter prevents the tubular drains from becoming clogged with large soil particles but allows smaller particles through.