Industrial Sieves, Part II: Perforated Plates

IS 2405 Part 2 — Scope: Key Specifications & Tables

Scope Summary:

• Covers industrial perforated plates with round/square holes.
• Defines aperture sizes, pitch, thickness, and tolerances.
• Applies to plates with various pitch-to-aperture ratios and thickness ranges.

1. Preferred Pitch-Aperture Combinations (Table 2)

• Pitch/aperture ratios and nominal sizes (R10 series).
• Approximate open area %.
• Pitch tolerances (average & individual).

Note: Tolerances tighten with smaller apertures.

2. Plate Thickness Ranges (Table 1)

• Thickness depends on aperture size and pitch/aperture ratio.

IS 2405 Part 2 — Key Definitions & Specifications for Perforated Plates

1. Definitions (Clause 2.0)

• Defines terms related to industrial perforated plates used in sieves.
• Aperture: The opening size in the plate.
• Pitch: Distance between centers of adjacent apertures.
• Aperture size and pitch are critical for sieve performance.

2. Aperture & Pitch Specifications (Clauses 4.2, 5.2, 5.3)

3. Example from Table 2 (Pitch-Aperture for Round Holes)

Summary

• Aperture size and pitch are standardized for performance and manufacturing consistency.
• Square holes have a max corner radius formula to ensure shape integrity.
• Plate thickness varies with aperture size and pitch/aperture ratio.
• Tolerances on pitch control manufacturing precision.

flowchart LR
    A[Aperture Size (A)] -->

Designation of Perforated Plates (IS 2405 Part 2)

Per Clause 3.1, industrial perforated plates are designated by:

• Aperture size and shape (round or square holes)
• Pitch and arrangement of apertures (e.g., 60° staggered or square pattern)
• Plate thickness
• Material of the plate

Preferred Pitch-Aperture Combinations (Clause 5.3, Table 2)

• Aperture sizes follow R 20 preferred number series (ISO 2194).
• Five classes of round/square holes with nominal open areas from 64% to 23%.
• Pitch is center-to-center distance between holes.
• Tolerances ensure manufacturing precision.

Labeling Requirements (Clause 6.1)

Each plate must have a permanent label with:

• Aperture size & shape
• Aperture arrangement (e.g., staggered or square)
• Plate thickness
• Material
• Overall dimensions
• Margin & fixing details
• Special requirements if any

Summary Diagram: Perforated Plate Designation

graph TD
  A[Perforated Plate] --> B[Aperture Size & Shape]
  A --> C[Pitch & Arrangement]
  A --> D[Plate Thickness]
  A --> E[Material]
  A --> F[Labeling Info]

Note: Use IS 2-1960 for rounding off values in compliance checks.

IS 2405 Part 2: Material and Plate Thickness for Industrial Perforated Plates

Key Points from Clause 3.1 & 4.2

• Plates are designated by aperture size & shape, pitch & arrangement, plate thickness, and material.
• Plate thickness is measured before perforation (Clause 2.7).
• Thickness ranges depend on aperture size, pitch, and pitch/aperture ratio.

Table 1: Range of Plate Thickness (mm) for Various Aperture Sizes & Pitch/Aperture Ratios

IS 2405 Part 2: Shape and Arrangement of Apertures

1. Shape & Arrangement (Clause 5.1)

• Round holes: 60° staggered arrangement (Fig. 1).
• Square holes:
  • Staggered at half pitch (Fig. 2).
  • In-line arrangement (Fig. 3).

2. Pitch and Aperture Ratios (Clause 5.3)

• Preferred pitch/aperture ratios: 1.25, 1.4, 1.6, 1.8, 2.0
• These ratios determine the open area and pitch for given aperture sizes.

3. Key Table Extract (Table 2 - Pitch & Aperture for Round Holes at 60° Stagger)

(Refer to IS 2405 Table 2 for full details)

4. Plate Thickness Range (Table 1 - Clause 4.2)

IS 2405 Part 2: Measurement of Aperture and Pitch

Key Specifications:

• Pitch/Aperture Ratios (Clause 5.3):
  Nominal pitch to aperture size ratios are:
  1.25, 1.4, 1.6, 1.8, 2.0

• Plate Thickness Range (Clause 4.2, Table 1):
  Thickness depends on aperture size and pitch/aperture ratio. Example ranges (in mm):

Tolerances (Clause 5.4 and 5.4.1):

• Tolerances on average aperture and average pitch from nominal values are given in Table 2 (not fully reproduced here).
• Tolerances on individual aperture or pitch size are also specified in Table 2.

Summary Formula for Nominal Pitch:

[ \text{Nominal Pitch} = \text{Pitch/Aperture Ratio} \times \text{Nominal Aperture Size} ]

Conceptual Diagram of Aperture and Pitch

flowchart LR
    A[NOMINAL APERTURE SIZE] --> B[NOMINAL PITCH]
    B --> C[Pitch/Aperture Ratio (1.25 to 2.0)]
    C --> B
    B --> D[Plate Thickness (per Table 1)]
    D --> E[Final Perforated Plate]

Note: For precise

IS 2405 Part 2 - Tolerances for Perforated Plates

Key Points from Clause 5.4 & Table 2:

• Tolerances apply to:

  • Measured average aperture size vs. nominal aperture.
  • Measured average pitch vs. nominal pitch.
  • Individual aperture size and pitch.

• Tolerance Values:

(Refer to IS 2405 Part 2 Table 2 for full details)

Additional Specifications:

• Pitch/Aperture ratios typically range from 1.25 to 2.
• Plate thickness varies with aperture size and pitch ratio (see Clause 4.2 Table 1).
• Tolerances are larger for bigger apertures.

Summary Formula for Tolerances:

• Average aperture tolerance ≈ 2-3% of nominal aperture size.
• Individual aperture tolerance ≈ 2 × average aperture tolerance.
• Average pitch tolerance ≈ 3-4% of nominal pitch.
• Individual pitch tolerance ≈ 2 × average pitch tolerance.

graph TD
A[Nominal Aperture

IS 2405 Part 2 - Sampling and Inspection Key Points

Sampling (Clause 8.2, 8.2.1, 8.3)

• Sample size: Number of sample perforated plates is per Level IV of Table 1 & Table 2 in IS 2500 (Part I)-1973.
• Inspection: All samples inspected for all specified requirements.
• Defect criteria: Any sample failing any requirement is defective.
• Acceptance: Lot conformity decided based on AQL = 2.5% as per Table 2 of IS 2500 (Part I)-1973.

Inspection Procedure

• Samples inspected by attributes (pass/fail criteria).
• Use sampling inspection tables from IS 2500 for acceptance/rejection.

Reference Table Extract (Sampling Plan)

(Exact values per IS 2500 Part I)

Summary:

• Select samples per IS 2500 Level IV.
• Inspect all samples fully.
• Reject lot if defective samples exceed acceptance number for AQL 2.5%.

flowchart TD
    A[Start: Lot Received] --> B[Select Samples per IS 2500 Level IV]
    B --> C[Inspect Samples for All Requirements]
    C --> D{Any Defective Samples?}
    D -- No --> E[Accept Lot]
    D -- Yes --> F[Count Defective Samples]
    F --> G{Defectives ≤ Acceptance Number?}
    G -- Yes --> E
    G -- No --> H[Reject Lot]

For detailed tables and exact sample sizes, refer to IS 2500 (Part I)-1973 Table 1 & 2.

IS 2405 Part 2: Quality Acceptance Criteria Summary

Sampling & Acceptance (Clause 8.3 & 8.2.1)

• Sampling based on Level IV from IS 2500 (Part I)-1973.
• Acceptance Quality Level (AQL) = 2.5% defective.
• If any sample plate fails any requirement, it is defective.
• Lot conformity judged by number of defective samples per IS 2500 attribute sampling tables.

Key Tables:

Tolerance on Pitch & Aperture (Excerpt from Table 2):

Procedure:

1. Select samples per IS 2500 Level IV.
2. Inspect all samples for specifications.
3. Count defective plates.
4. Accept/reject lot based on AQL 2.5% criteria.

flowchart TD
    A[Select Samples as per IS 2500 Level IV] --> B[Inspect Samples for All Requirements]
    B --> C{Any Defective Samples?}
    C -- No --> D[Accept Lot]
    C -- Yes --> E[Count Defective Samples]
    E --> F{Defect Count ≤ AQL 2.5% Limit?}
    F -- Yes --> D
    F -- No --> G[Reject Lot]

For detailed sampling tables and acceptance numbers, refer to IS 2500 (Part I)-1973.