IS 8419 Part 2 (1984) delineates the specifications for underdrainage systems employed in rapid sand gravity filtration units within water treatment facilities. It details the design, materials, fabrication, and performance benchmarks for both pipe grid and false bottom floor underdrainage configurations, ensuring efficient collection and distribution of filtered and backwash water. This standard serves as a crucial reference for engineers and designers engaged in water filtration infrastructure to guarantee dependable and uniform filtration outcomes.
Overview
IS 8419 Part 2 (1984) delineates the specifications for underdrainage systems employed in rapid sand gravity filtration units within water treatment facilities. It details the design, materials, fabrication, and performance benchmarks for both pipe grid and false bottom floor underdrainage configurations, ensuring efficient collection and distribution of filtered and backwash water. This standard serves as a crucial reference for engineers and designers engaged in water filtration infrastructure to guarantee dependable and uniform filtration outcomes.
Audience
Contents
Structure
This section outlines the scope of IS 8419 Part 2 concerning materials for underdrainage pipe grids, both with and without nozzles. It details the acceptable materials for components such as manifolds, laterals, seals, saddles, tees, and hook belts, referencing pertinent IS standards for asbestos cement, UPVC, HDPE, RCC (Grade M20), cast iron, rubber, stainless steel, and asbestos. The section also includes illustrative material flow diagrams for these components.
This part categorizes underdrainage systems into pipe grids without nozzles and pipe grids with nozzles, specifying the material choices and IS codes applicable to each. It includes detailed tables for components' materials and a schematic representation of pipe grids without nozzles showing the assembly of manifolds, laterals, saddles, and tees.
Focused on pipe grid types, this section describes the materials used for pipe grids without nozzles, highlighting asbestos cement pipes, UPVC, HDPE, RCC M20 grade concrete, cast iron, and rubber seals. It also presents diagrams illustrating the structural layout of pipe grids and emphasizes adherence to IS codes for all materials.
This subsection provides detailed information about the materials and design of manifolds and laterals, including perforation patterns, orifice orientation, and hydraulic design formulas. It explains the role of manifolds as main headers and laterals as distributors, including hydraulic discharge computations to ensure uniform flow.
This section enumerates the acceptable materials for underdrainage system components, differentiating between pipe grids with and without nozzles. It references relevant IS codes for each material type and discusses their suitability based on durability and compatibility with operating conditions.
Covers construction practices such as embedding pipes in concrete slabs, use of rubber seals for leak prevention, and corrosion-resistant materials like stainless steel for structural elements. It emphasizes proper jointing and alignment to maintain system integrity.
Describes the pipe grid system that includes nozzles, detailing material specifications for manifolds, laterals, and nozzles themselves, as well as associated fittings. It covers design considerations for nozzle placement and hydraulic performance.
Details the components and materials for manifolds and laterals fitted with nozzles, including discharge calculations. It discusses materials such as AC pipes, UPVC, HDPE, RCC, cast iron, rubber seals, and stainless steel hook belts, along with design considerations to ensure flow uniformity and durability.
Explains the construction of filter floors involving lateral pipes connected to manifolds, embedding in reinforced concrete slabs, and installation of nozzle plates. It specifies requirements for slab thickness, reinforcement, removable precast slabs for maintenance access, and finishes to ensure flush nozzle placement.
Describes the false bottom floor underdrainage system designed to support filter media and distribute water uniformly. It includes construction details such as concrete slab embedding, lateral pipe arrangements, nozzle plate placements, perforation sizing, and floor thickness, along with hydraulic head loss formulas.
Outlines the primary functions of filter floors, including supporting the filter bed and providing pathways for filtered and backwash water. It describes the integration of lateral pipes, nozzle placements, perforation design, and manifold construction with removable precast slabs to facilitate maintenance.
Focuses on techniques for constructing filter slabs, including the use of precast or cast-in-situ concrete, installation of internally threaded bushes for nozzles, and material specifications for nozzles. It provides guidance on leveling, sealing with rubber O-rings, and preventing corrosion.
Discusses hydraulic design aspects including material selection per IS codes, nozzle design impact on flow distribution, and formulas for flow rate and head loss calculation. It emphasizes achieving uniform flow with minimal head loss for optimal filtration performance.
Details performance standards and testing procedures for underdrainage systems, covering leakage checks, flow uniformity, and structural strength under operational pressures. It reinforces the importance of material compliance and concrete grade standards.
Highlights design requirements to facilitate inspection and maintenance, including material durability, provision of removable covers, access openings, and proper jointing. It specifies recommended dimensions for access points and drainage slopes to ensure ease of upkeep.
Frequently Asked
Per IS 8419 Part 2, the materials for manifolds and laterals differ based on the underdrainage type. For pipe grids without nozzles, manifolds can be constructed from asbestos cement pressure pipes, unplasticized PVC, HDPE, or M20-grade reinforced cement concrete, while laterals include asbestos cement pipes, cast iron, PVC, and HDPE. For pipe grids with nozzles, manifolds use RCC M20, PVC, AC pressure pipes, or HDPE, and laterals utilize glazed stoneware, PVC, or HDPE. These materials ensure structural integrity, chemical resistance, and durability as referenced by respective IS codes.
IS 8419 Part 2 specifies that nozzles are installed by screwing them into internally threaded bushes grouted into precast or cast-in-situ concrete slabs. The lateral pipes have holes on top to accommodate nozzle plates, which are embedded and grouted within reinforced concrete. Materials recommended for nozzles include unplasticized PVC, HDPE, stainless steel, and brass. The assembly ensures a secure, leak-proof fit with the floor surface finished flush with the nozzle plates for uniform water distribution.
To achieve uniform water distribution, IS 8419 Part 2 mandates that filtered water is collected evenly across the filter bed and conveyed efficiently to outlet chambers. The filter floor is perforated with small, closely spaced short tubes or orifices to create controlled head loss, promoting equal wash water distribution. Backwash water is distributed via a header channel with openings on both vertical walls, ensuring consistent flow of water and air along the filter length for effective cleaning.
The standard covers two primary underdrainage system types: pipe grids without nozzles and pipe grids with nozzles, along with false bottom floor types. These configurations are designed to meet the hydraulic and structural requirements for rapid sand gravity filtration, facilitating uniform filtered and wash water distribution within water treatment filters.
IS 8419 Part 2 requires lateral pipes with top holes for nozzles to be grouted firmly into the concrete filter floor, which is reinforced with steel and constructed with minimum M20-grade RCC. Pipes bridging the filter channel include slots underneath for water flow. The concrete slab incorporates removable precast sections for access, and all reinforcement is fully embedded to prevent corrosion. The filter floor surface is finished smooth and flush with nozzle plates, ensuring structural stability and water tightness.
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