Continuous Unibody Filter Underdrain is a continuous, seamless underdrain system manufactured in the factory through a single extrusion molding process. It stands in clear contrast to traditional underdrain systems which are assembled piece by piece on-site using underdrain blocks.
The Continuous Unibody Filter Underdrain, through factory prefabrication, high-performance materials, and scientifically sound structural design, perfectly resolves the shortcomings of traditional underdrains in terms of leakage, durability, installation efficiency, and comprehensive cost. It is the ideal choice for the core component of a filter basin system.
The Continuous Unibody Filter Underdrain main uses engineering plastics, such as high-density polyethylene (HDPE) or modified polyvinyl chloride (PVC). Utilizing plastic extrusion molding technology, it is possible to extrude pipe sections with complex hollow reinforcing ribs in a single pass, reaching lengths of up to 6 meters, 12 meters, or even longer.
The shape is fundamentally consistent with the most popular existing HDPE underdrains, with scientifically distributed reinforcing ribs designed on the sides and bottom. This design maximizes material savings and reduces weight while ensuring extremely high structural strength.
Smooth Inner Wall: The internal surface, precisely extruded and formed in the factory, is extremely smooth, resulting in a very low Manning coefficient ($n$ value) and minimal flow resistance.
Low Scaling Tendency: The chemical inertness of the material makes it difficult for microorganisms and scale to adhere, leading to minimal attenuation of drainage capacity after long-term use.
Seamless System: As a "unibody" product, the pipe body contains no joints. The custom lengths matching the filter basin length also mean the number of connection points in the entire underdrain system is zero, achieving "zero leakage."
In contrast, traditional underdrains are about 1 meter long, requiring multiple socket connections sealed with rubber rings. It is well known that HDPE exhibits creep, and rubber rings have fatigue strength. However, since the underdrain system is the core of the filter, buried deep at the bottom of the media layer and subjected to long-term pressure, the reliability of the unibody underdrain is clearly much greater than that of traditional solutions.
High Structural Strength: Through scientific "structural wall" design (such as hollow ribs and vertical ribs), extremely high ring stiffness and compressive strength are achieved while minimizing material usage, allowing it to withstand deep filter media pressure.
High Toughness: The material has excellent resistance to impact and seismic activity, can adapt to uneven foundation settlement, and is not prone to breakage.
Extreme Corrosion Resistance: It has strong resistance to common acids, alkalis, salts, and microbial erosion found in soil, resulting in a long design service life.
Rapid Installation: The unibody underdrain eliminates the most time-consuming on-site splicing work, leading to extremely fast construction speed and significantly shortening the construction period.
Low Comprehensive Cost: Although the material cost per meter may be higher, the total life-cycle cost is much lower than traditional solutions due to its fast installation, no need for curing/maintenance, low transport and hoisting costs, and minimal long-term maintenance.
Green Material: HDPE is an environmentally friendly and non-toxic material, and its smooth inner wall is not conducive to bacterial growth.
Recyclable: The material is 100% recyclable, aligning with the concept of sustainable development.
Drinking Water Protection: Its excellent anti-leakage characteristics effectively prevent leakage from the filter media from contaminating the filtered water.
