Requirements for rapid sand gravity filtration equipment, Part 2: Under drainage system

Scope of IS 8419 Part 2: Underdrainage System Materials

This part covers materials for underdrainage pipe grids with and without nozzles.

Key Tables on Material Specifications:

Notes:

• RCC refers to Grade M-20 concrete as per IS 456.
• UPVC = Unplasticized Polyvinyl Chloride.
• AC = Asbestos Cement.
• HDPE = High-Density Polyethylene.

Summary Diagram (Material Flow):

graph TD
    A[Manifold] -->|Without Nozzle| B[AC, UPVC, HDPE, RCC]
    A -->|With Nozzle| C[RCC, UPVC, AC, HDPE]
    D[Laterals

IS 8419 Part 2: Underdrainage Systems Overview

Types of Underdrainage Systems (Clause 2.0)

• a) Pipe grid without nozzles
• b) Pipe grid with nozzles

Key Specifications for Pipe Grid Without Nozzles (Clause 2.1.2)

Notes:

• Materials must comply with the respective IS codes for durability and compatibility.
• RCC concrete grade M20 is standard for structural components.
• Pipes include AC (Asbestos Cement), UPVC, HDPE, and Cast Iron depending on application and environment.

Conceptual Diagram of Pipe Grid Without Nozzles

graph LR
  M[Manifold] --> L1[Laterals]
  M --> L2[Laterals]
  L1 --> S1[Saddle]
  L2 --> S2[Saddle]
  S1 --> T1[Tee]
  S2 --> T2[Tee]

This shows the manifold feeding lateral pipes connected via saddles and tees.

For pipe grid with nozzles, refer to IS 8419 Part 2 Table 2.2 (not fully provided here) for nozzle types and spacing.

Summary:
Use appropriate pipe and joint materials per IS codes, ensure RCC components are M20 grade, and select system type based on site drainage needs.

IS 8419 Part 2: Pipe Grid Types - Key Specifications

1. Pipe Grid Types:

• Without Nozzles (Clause 2.1.2)
• With Nozzles (Clause 2.2.2)

2. Material of Construction for Pipe Grid WITHOUT Nozzles (Table 1, Clause 2.1.2):

Notes:

• AC pressure pipe: Asbestos cement pipes suitable for pressure applications.
• UPVC & HDPE: For corrosion resistance and durability.
• RCC: Reinforced cement concrete, Grade M20 for structural strength.
• Cast iron: For durability in laterals and saddles.
• Rubber 'O' rings: For sealing joints.

Summary Diagram (Pipe Grid Without Nozzles):

graph TD
    A[Manifold] --> B[Laterals]
    B --> C[Saddle]
    C --> D[Tee]
    D --> E[Hook belt]
    B --> F['O' Rings]

Use these materials as per IS 8419 Part 2 for designing underdrainage pipe grids in water treatment filtration systems.

IS 8419 Part 2 — Manifold and Laterals Key Points

Components & Materials (Clause 2.1.2, Table 2.2)

Perforation Specifications (Clause 2.1.3.2)

• Laterals have perforations drilled in single or double rows.
• Orifices are directed vertically downward or at an angle on either side of vertical diameter.
• Spacing and size depend on hydraulic design.

Typical Design Notes:

• Manifold acts as main header.
• Laterals distribute flow, with perforations controlling discharge.
• Hydraulic design governs orifice diameter (d) and spacing (s) to ensure uniform flow.

Example: Hydraulic Design Formula for Orifice Discharge

[ Q = C_d \times A \times \sqrt{2gH} ]

Where:

• (Q) = discharge per orifice (m³/s)
• (C_d) = discharge coefficient (~0.6)
• (A = \pi d^2/4) = orifice area (m²)
• (g) = acceleration due to gravity (9.81 m/s²)
• (H) = pressure head above orifice (m)

flowchart LR
    M[Manifold/Header]
    M --> L1[Laterals with Perfor

IS 8419 Part 2: Materials of Construction for Underdrainage Systems

1. Pipe Grid Without Nozzles (Clause 2.1.2, Table 1)

2. Pipe Grid With Nozzles (Clause 2.2.2, Table 2)

Key Notes:

• RCC Grade M-20: Concrete mix with characteristic compressive strength of 20 MPa as per IS 456.

IS 8419 Part 2: Construction Details for Underdrainage System

Key Construction Specifications (Clause 2.1.2 & 2.2.3, 3.3)

Construction Notes:

• RCC components use Grade M20 concrete as per IS 456-1978.
• Pipes must conform to respective IS standards for pressure, durability, and water-tightness.
• Rubber 'O' rings ensure sealing and prevent leakage.
• Stainless steel hook belts provide corrosion resistance.

Summary Table for Materials:

IS 8419 Part 2 (1984) - Pipe Grid with Nozzles: Key Specifications

1. Types of Underdrainage Systems (Clause 2.0)

• a) Pipe grid without nozzles
• b) Pipe grid with nozzles

2. Material of Construction (Clause 2.2.2 & Table 2)

For pipe grid with nozzles, materials are specified similarly to pipe grid without nozzles (Table 1), but adapted for nozzle fittings.

3. Notes:

• Concrete: RCC components use Grade M-20 concrete per IS 456.
• Pipe materials must be compatible for pressure and chemical resistance.
• Nozzle design depends on flow requirements; refer to hydraulic design codes for sizing.

Summary Table for Pipe Grid with Nozzles Materials

IS 8419 Part 2: Manifold and Laterals with Nozzles Key Points

1. Components & Materials (Clause 2.1.2, Table 2.2)

2. System Description (Clause 2.2.1)

• The system consists of a main manifold/header and laterals with nozzles connected.
• Nozzles allow water distribution through laterals.

3. Design Considerations

• Use materials as per IS codes for durability and pressure requirements.
• RCC components designed as per IS 456 for concrete grades.
• Rubber 'O' rings ensure leak-proof joints.
• Cast iron and stainless steel provide mechanical strength where required.

Typical Design Formula (General Guidance)

• Flow through nozzles:

[ Q = C_d A \sqrt{2gH} ]

Where:

• (Q) = Discharge through nozzle (m³/s)
• (C_d) = Discharge coefficient (~0.6-0.9)
• (A) = Area of nozzle opening (m²)
• (g) = Acceleration due to gravity (9.81

Key Specifications & Construction Details from IS 8419 Part 2 (1984) for Filter Floor & Nozzle Installation

1. Filter Floor Construction (Clauses 2.2.3.1, 3.1, 3.2)

• Filter floor consists of lateral pipes connected to a central manifold/channel.
• Pipes have holes on top to receive bosses or nozzle plates.
• Pipes bridging the channel have slots underneath for water flow.
• Entire pipe assembly is grouted and embedded in concrete with reinforcement.
• Floor surface is screeded smooth and flush with nozzle plates.
• Floor thickness and perforation size ensure:
  • Proper loss of head control.
  • Even wash water distribution.
• Openings: small and closely spaced short tubes or orifices.

2. Manifold Construction (Clause 2.1.3.1)

• Manifold: pipe or RCC duct below filter floor.
• Covered with in-situ RCC slab, minimum M20 grade.
• Slab includes 1-2 removable gaps for shutter removal, covered by precast slabs.
• Precast slabs ≤ 0.6 m² area, reinforced and jointed with floor reinforcement.
• No exposed reinforcement or MS bars to avoid corrosion.

Summary Table

Construction Sequence (Simplified)

flowchart TD
    A[Prepare manifold (pipe/RCC duct)] --> B[Cover with RCC slab (M20)]
    B --> C[Place precast slabs in gaps]
    C --> D[Install lateral pipes with holes & slots]
    D --> E[Grout pipes & embed in concrete with reinforcement]
    E --> F[Screed

False Bottom Floor Type (IS 8419 Part 2 - 1984) underdrainage system specifications:

Key Specifications:

• Purpose: Provides uniform distribution and support for filter media in water treatment filters.
• Construction: Concrete floor embedded with reinforcement, incorporating lateral pipes and nozzle plates.
• Floor Thickness: Determines whether perforations are made by short tubes or orifices.
• Perforations: Small, closely spaced openings to control loss of head and ensure even wash water distribution.

Essential Elements:

• Lateral Pipes: Series of pipes with holes on top for nozzle plates; connected to a central manifold.
• Manifold: Positioned at the front end; connects filtered water outlet and upwash inlet pipes (Clause 2.2.3.3).
• Nozzle Plates: Screwed into lateral pipes; flush with floor surface after screeding.
• Slots: Underside of pipes bridging the central channel to allow flow.

Typical Design Considerations:

Formula for Head Loss through Orifices:

[ h = \frac{Q^2}{C_d^2 A^2 2g} ] Where:

• (h) = head loss (m)
• (Q) = flow rate through orifice (m³/s)
• (C_d) = discharge coefficient (typically 0.6-0.65)
• (A) = area of orifice (m²)
• (g) = acceleration due to gravity (9.81 m/s²)

flowchart LR
    Manifold[Manifold at Front End]
    PipeGrid[Lateral Pipes with Nozzle Plates]
    FilterFloor[Concrete Floor with Reinforcement]
    Nozzles[Nozzle Plates]
    FilterFloor --> PipeGrid --> Manifold
    PipeGrid --> Nozzles

Summary: The false bottom floor

Functions of Filter Floors (IS 8419 Part 2)

1. Primary Functions (Clause 3.1):

   • Support the filter bed.
   • Create a waterway beneath the filter for collecting filtered water and distributing wash water.

2. Filter Floor Construction (Clause 2.2.3.1):

   • Consists of lateral pipes connected to a central manifold.
   • Pipes have top holes for nozzle plates; nozzles are screwed in.
   • Pipes bridging the channel have slots underneath for water flow.
   • Pipes grouted and embedded in concrete with reinforcement; surface screeded flush with nozzle plates.

3. Water Distribution (Clause 3.2):

   • Floor perforated with short tubes/orifices to control loss of head and ensure even wash water distribution.
   • Openings are small and closely spaced.

4. Manifold Specifications (Clause 2.1.3.1):

   • Manifold: pipe or RCC duct below floor, covered by in-situ RCC slab (min M-20).
   • Slab includes removable precast slabs (max 0.6 m² each) for shutter removal.
   • Reinforcements jointed and covered to prevent corrosion.

Key Points Summary:

flowchart TB
    A[Manifold (RCC duct/pipe)] --> B[Filter floor with lateral pipes]
    B --> C[Nozzle plates with nozzles]
    C --> D[Filter bed supported above]
    B --> E[Waterway for filtered & wash water]

This setup ensures structural support, controlled water flow, and easy maintenance access as per IS 8419 Part 2.

IS 8419 Part 2: Slab Construction & Nozzle Fittings Key Points

1. Slab Construction (Clause 3.3.1 & 3.3.3)

• Slabs can be precast or cast-in-situ.
• Nozzle bushes (internal threaded) must be grouted into concrete.
• For cast-in-situ slabs, bushes are held in fixtures to ensure uniform pitching and leveling.
• Nozzles are screwed into these bushes.

2. Nozzle Materials (Clause 3.3.1)

• Nozzles should be made from:
  • Unplasticized PVC
  • HDPE
  • Stainless steel
  • Brass

3. Material Specifications for Underdrainage System

4. Additional Notes

• Use internal threaded bushes for nozzle fitting.
• Ensure uniform leveling during concreting for cast-in-situ slabs.
• Use rubber 'O' rings for sealing (IS: 5382-1969).

Summary Diagram of Slab with Nozzle Bush

graph LR
A[Concrete Slab] --> B[Internal Threaded Bush]
B --> C[Nozzle (PVC/HDPE/SS/

Hydraulic Design Considerations per IS 8419 Part 2 (Underdrainage System)

Key Materials & References (Tables 2.1.2 & 2.2.2)

Hydraulic Design Notes:

• Pipe materials must conform to IS standards for durability and chemical resistance.
• RCC Grade M-20 concrete is standard for structural components.
• Nozzle design affects flow distribution; materials chosen based on corrosion and wear resistance.
• Underdrainage system should ensure uniform flow with minimal head loss.

Typical Hydraulic Formula (General Guidance)

• Flow rate (Q):
  [ Q = A \times V ] where
  ( A ) = cross-sectional area (m²),
  ( V ) = velocity (m/s).

• Head loss (h_f) in pipes (Darcy-Weisbach):
  [ h_f = f \frac{L}{D} \frac{V^2}{2g} ] where
  ( f ) = friction factor,
  ( L ) = pipe length,
  ( D ) = diameter,
  ( g ) = acceleration due to gravity.

flowchart LR
    A[Manifold] --> B[Laterals]
    B --> C[Nozzles]
    C --> D[Filter

IS 8419 Part 2: Performance & Testing Requirements for Rapid Sand Gravity Filtration Underdrainage System

Key Specifications from Clause 2.1.2 & Table 2.2 (Material of Construction)

Performance & Testing Notes:

• Material compliance with IS codes ensures durability and chemical resistance.
• Testing involves leakage checks, flow distribution uniformity, and structural integrity under operational pressures.
• RCC components must conform to M-20 concrete grade as per IS 456.
• Pipes and fittings must be pressure-rated as per their respective IS standards.

Summary of Material Selection Criteria

flowchart TD
    A[Underdrainage System] --> B[Manifold]
    A --> C[Laterals]
    A --> D[Seals ('O' Rings)]
    A --> E[Saddles]
    A --> F[Tees]
    A --> G[Hook Belts]

    B --> B1[AC Pressure Pipe (IS 1592)]
    B --> B2[UPVC (IS 4985)]
    B --> B3[HDPE (IS 4984)]
    B --> B4[RCC M-20 (IS 456)]

    C --> C

IS 8419 Part 2: Maintenance and Access Provisions - Key Points

1. Materials for Underdrainage System (Clause 2.1.2, Table 2.2)

2. Construction (Clauses 2.1.3, 2.2.3, 3.3)

• Ensure easy access for inspection and maintenance.
• Use durable materials compatible with soil and water conditions.
• Provide removable covers or access points at critical junctions.
• Maintain proper alignment and jointing for leak-proof operation.

3. Maintenance Access Design Formula (General Engineering Practice)

• Minimum access opening size: 600 mm × 600 mm
• Manhole depth: as per pipe diameter + 300 mm clearance
• Slope for drainage pipes: 1% to 2% to avoid sedimentation

flowchart LR
    A[Manifold] --> B[Laterals]
    B --> C[Nozzles / Outlets]
    A --> D[Access Points]
    D --> E[Maintenance]

Summary: Use IS-specified materials, provide adequate access openings, and ensure construction allows easy inspection and repair.