eyepiece and screen graticules for determination of particle size of powders
1969 Edition

IS 5257 - Scope and Fundamental Criteria for Graticules

Scope

• Pertains to eyepiece and screen graticules employed in determining particle size of powders that pass through a 75-micron IS sieve.
• Designed for use with optical microscopes where particle images are compared against calibrated reference circles.
• Ensures conformity with standards such as BS 3625:1963 for consistency.

Principal Specifications (Clause 2.3.1 & Table 1)

Additional Details

• Boundary lines extend 2.5 units to intersect.
• Calibration marks on the longer axis are 7.5 units in length, symmetrically positioned.
• Ruling line thickness is ≤ 1/5 unit (max 1/500th grid length).
• Measurements between centers of ruling lines; circle diameters measured at outside edges.

flowchart LR
    A[Powder Sample] --> B[Microscope with Graticule]
    B --> C[Particle Image Compared to Reference Circles]
    C --> D[Particle Size Distribution Determination]

This standard guarantees accurate and reproducible particle size measurements using standardized graticules.

IS 5257: Constructional Requirements for Eyepiece and Screen Graticules

Core Specifications (Clause 2.3.1 & Table 1):

• Grid Dimensions:
  • Length: 100 units
  • Breadth: 50 ± 0.25 units
• Boundary Lines: Extend by 2.5 units beyond grid edges to form crosses.
• Calibration Marks: Positioned on the longer axis with a length of 7.5 units, symmetrically arranged.
• Distance Between Calibration Marks: 85.4 ± 0.25 units
• Ruling Line Thickness: ≤ 1/5 unit (max 1/500th of grid length), consistent within ±20%.
• Circle Diameters (units ± tolerance):

• Lengths are measured center to center of ruling lines; circle diameters between outer edges.

Purpose and Application

• Graticules are utilized for determining particle sizes of powders passing through a 75-micron sieve.
• Particles are visually compared under microscopes against reference circles to ascertain size.

Diagrammatic Overview

graph TD
    A[Grid Boundary Lines] -->|Extend 2.5 units| B[Crossing Lines]
    B --> C[Rectangular Grid 100 x 50 units]
    C --> D[Calibration Marks 7.5 units symmetrically positioned]
    C --> E[Subdivision Lines Creating Defined Areas]
    C --> F[Open Circles with Specified Diameters]

Reference: IS 5257 (1969) — Specification for eyepiece and screen graticules used in particle size measurement.

IS 5257: General Design Principles for Graticules

Principal Specifications (Clause 2.3.1 & Table 1)

• Grid Dimensions:
  • Length: 100 units
  • Breadth: 50 ± 0.25 units
• Calibration Marks:
  • Length: 7.5 units on the longer axis
  • Spacing: 85.4 ± 0.25 units between marks
• Ruling Lines:
  • Thickness ≤ 1/5 unit (max 1/500th grid length)
  • Uniformity within ±20%
• Circle Diameters (units ± tolerance):

Notes:

• Lengths measured between centers of ruling lines.
• Circle diameters measured between outside edges.
• Grid subdivided as per figure with specified area ratios.
• Pattern includes rectangular grid, calibration marks, open and solid circles (numbered 1–7), grid length label, and manufacturer's details.

Unit Length Calculation:

[ \text{Unit length} = \frac{\text{Grid length}}{100} ]

graph TB
    A[Rectangular Grid] --> B[Calibration Marks (7.5 units)]
    A --> C[Subdivision per Figure]
    A --> D[Open Circles (7 sizes)]
    A --> E[Solid Circles (7 sizes)]
    B --> F[Spacing Between Marks: 85.4 ± 0.25 units]
    D --> G[Circle Diameters with Tolerances]

This framework ensures accurate and reproducible graticule design following IS 5257.

IS 5257: Layout of Circles and Rulings — Key Features

1. Graticule Pattern (Clause 2.2)

• Rectangular grid subdivided as per figure.
• Two calibration marks on the longer axis, crossing at intersections extended by two units.
• Seven open and seven solid circles, numbered 1 through 7.
• Label "GRID LENGTH" with actual measurement in millimeters.
• Manufacturer's name and standard number included.

2. Construction Details (Clause 2.3.1)

• Boundary lines extend by 2.5 units beyond the grid edges to intersect.
• Calibration marks length: 7.5 units, symmetrically located.
• Subdivision lines create defined areas as per specification.
• Ruling line thickness ≤ 1/5 unit (1/500th of grid length), with ±20% tolerance.

3. Dimensions (Table 1)

• Unit length equals 1/100th of grid length.
• Tolerances apply to both eyepiece and screen graticules, with minimum precision of 5 microns.

Unit Length Formula:

[ \text{Unit length} = \frac{\text{Grid length (mm)}}{100} ]

Conceptual Visualization:

graph LR
    A[Rectangular Grid] --> B[Calibration Marks]
    B --> C[Subdivisions]
    B --> D[Open and Solid Circles]
    D --> E[Circle Diameter Tolerances]

This layout supports precise, standardized graticule production.

IS 5257: Proportional Dimensions for Grid and Circles

Specifications (Clause 2.3 & Table 1)

• Base unit: Defined as 1/100th of the grid length.
• Grid length: Fixed at 100 units.
• Grid breadth: 50 ± 0.25 units.
• Calibration marks interval: 85.4 ± 0.25 units.
• Circle diameters (units ± tolerance):

Additional Construction Notes (Clause 2.3.1)

• Boundary lines extend 2.5 units beyond the grid to intersect.
• Calibration marks on the longer axis are 7.5 units long and symmetric.
• Ruling lines have thickness ≤ 1/5 unit, consistent within ±20%.
• Lengths measured between centers of ruling lines; circle diameters between outer edges.

Actual Grid Dimensions (Clause 2.4)

• Grid length must be within ±2% of the nominal value.
• Screen graticule grid length minimum: 106.1 mm.

Diagrammatic Representation:

graph TD
    A[Rectangular Grid] -->|Length = 100 units| B[Grid Length]
    A -->|Breadth = 50 ± 0.25 units| C[Grid Breadth]
    A --> D[Calibration Marks]
    D -->|Length = 7.5 units| E[Long Axis Marks]
    A --> F[Open Circles]
    F --> G1[Circle 1: 1.41 ± 0.03 units]
    F --> G2[Circle 2: 2.00 ± 0.04 units]

This ensures accurate, standardized dimensions for graticules.

IS 5257 - Grid Dimensions for Graticules

Essential Specifications & Formulas:

• Grid length (long side): 100 units (with base unit = 1/100th of grid length).
• Grid breadth (short side): 50 ± 0.25 units.
• Calibration marks spacing: 85.4 ± 0.25 units.
• Line width of rulings: ≤ 1/5 unit (max 1/500th of grid length), uniform within ±20%.
• Calibration mark length: 7.5 units on the longer axis, symmetrically placed.
• Boundary lines: Extended by 2.5 units beyond the grid to intersect.

Circle Diameters (units ± tolerance):

Additional Information:

• Actual grid length must be within ±2% of the marked length.
• Minimum grid length for screen graticules: 106.1 mm.
• Measurements are taken center to center for ruling lines, and outside edge to outside edge for circle diameters.

Unit Length Formula:

[ \text{Unit length} = \frac{\text{Grid length}}{100} ]

graph LR
A[Grid Length = 100 units]
B[Grid Breadth = 50 ± 0.25 units]
C[Calibration Marks Length = 7.5 units]
D[Calibration Marks Distance = 85.4 ± 0.25 units]
E[Circle Diameters per Table]
A --> B
A --> C
A --> D
A --> E

This guarantees precise and consistent graticule dimensions for accurate measurement.

IS 5257 - Marking Protocols and Dimension Specifications

1. Marking Requirements (Clause 3.1)

• Manufacturer’s name, trademark, or identifying mark must be present.
• The Indian Standard number (IS 5257) should be clearly indicated.
• Optional inclusion of ISI Certification Mark, following ISI regulations, to ensure quality assurance.

2. Graticule Dimension and Features (Clause 2.3.1 & Table 1)

• Ruling line thickness ≤ 1/5 unit (1/500th of grid length), uniform within ±20%.
• Calibration marks length: 7.5 units, symmetrically placed on the longer axis.
• Boundary lines extend 2.5 units beyond intersections.

3. Pattern Components (Clause 2.2)

• Rectangular grid subdivided as per figure.
• Two calibration marks crossing the longer axis.
• Sets of seven open and seven solid circles numbered 1 to 7.
• Markings include "GRID LENGTH" with actual length in mm.
• Manufacturer’s name and IS number.

Visual Summary (Mermaid Diagram)

graph TD
    A[Rectangular Grid] --> B[Boundary lines extended]
    B --> C[Calibration marks]
    C --> D[Circles]
    D --> E[Markings and Labels]

This marking protocol ensures traceability and quality, aligning with IS 5257 standards.

IS 5257 Marking Requirements for Manufacturer and Standard Number (Clause 3.1):

• The graticule must display the manufacturer’s name, trademark, or other identification.

• The Indian Standard code (IS 5257) must be visibly marked.

• ISI Certification Mark (Optional):

  • Signifies adherence to IS standards.
  • Indicates inspection, testing, and quality control compliance.
  • Usage governed by rules of the Indian Standards Institution.

Reference Table: Key Dimensions of Standard Graticule (Clause 2.3.1)

*Unit based on grid length (1 unit = 1/500th of grid length).

Schematic Diagram:

graph TD
  A[Rectangular Grid] --> B[Length = 100 units]
  A --> C[Breadth = 50 ± 0.25 units]
  A --> D[Calibration Marks (7.5 units)]
  A --> E[Circles of Various Diameters]
  E --> F[Diameters Range 1.41 to 11.31 units ± tolerances]
  A --> G[Ruling Line Width ≤ 1/5 unit]

Manufacturer and IS number marking provide traceability and guarantee compliance with IS 5257, critical for accurate particle size measurement.

IS 5257: Relevant Standards and References

Associated Indian Standards for Sieving and Particle Size Analysis:

Summary of Graticule Specifications (IS 5257):

• Grid length: 100 units
• Grid breadth: 50 ± 0.25 units
• Calibration mark spacing: 85.4 ± 0.25 units
• Circle diameters:
  • 1: 1.41 ± 0.03 units
  • 2: 2.00 ± 0.04 units
  • 3: 2.83 ± 0.06 units
  • 4: 4.00 ± 0.08 units
  • 5: 5.66 ± 0.10 units
  • 6: 8.00 ± 0.12 units
  • 7: 11.31 ± 0.14 units
• Ruling line thickness: ≤ 1/5 unit (max 1/500th grid length), consistent within ±20%

Marking Requirements (Clause 3.1):

• Manufacturer’s name or trademark
• IS Standard number (IS 5257)

Purpose:

These standards ensure uniformity and accuracy in particle size determination for powders.

IS 5257 - Standard Graticule Illustration (Figure 1) Key Details

1. Pattern and Components (Clause 2.2)

• Rectangular grid with length 100 units and breadth 50 ± 0.25 units.
• Two calibration marks on the longer axis, each 7.5 units in length.
• Seven open circles and seven solid circles, labeled 1 through 7.
• Markings include "GRID LENGTH" followed by actual length in millimeters, manufacturer’s name, and standard number.

2. Construction Features (Clause 2.3.1)

• Grid boundary lines extend 2.5 units beyond grid to form intersections.
• Distance between calibration marks: 85.4 ± 0.25 units.
• Ruling line thickness ≤ 1/5 unit (maximum 1/500th of grid length), consistent within ±20%.
• Circle diameters measured between outer edges of ruling lines.

3. Circle Diameters (Table 1)

4. Notes:

• Lengths and distances measured center-to-center of ruling lines.
• Circle diameters measured outside edge to outside edge.
• Graticule printed with black rulings on a diffusing background for screen graticules.

flowchart LR
    A[Rectangular Grid]
    A --> B[Length = 100 units]
    A --> C[Breadth = 50 ± 0.25 units]
    A --> D[Calibration Marks (7.5 units)]
    A --> E[Seven Open and Seven Solid Circles]
    E --> F[Diameters as Specified in Table 1]

This figure represents the official design for graticules as per IS 5257.