eyepiece and screen graticules for determination of particle size of powders

IS 5257 - Scope & Key Specifications for Graticules

Scope

• Applies to eyepiece and screen graticules for particle size determination of powders passing through a 75-micron IS sieve.
• Used with microscopes to compare particle images with reference circles of known sizes.
• Ensures standardization aligned with BS 3625:1963.

Key Specifications (Clause 2.3.1 & Table 1)

Additional Notes

• Grid boundary lines extend by 2.5 units to cross.
• Calibration marks on longer axis are 7.5 units long, symmetrically placed.
• Ruling line width ≤ 1/5 unit (max 1/500 grid length).
• Measurements between centers of ruling lines; circle diameters measured outside edges.

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

This standard ensures precise, repeatable particle size measurements using calibrated graticules.

IS 5257: Construction of Eyepiece and Screen Graticules

Key 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 cross.
• Calibration marks on longer axis: length = 7.5 units, symmetrically placed.
• Distance between calibration marks: 85.4 ± 0.25 units
• Ruling line width: ≤ 1/5 unit (max 1/500th of grid length), uniform within ±20%.
• Diameters of open circles (units ± tolerance):

• Measurement basis: Between centers of ruling lines for lengths, and outside edges for circle diameters.

Purpose & Use

• Graticules are used for particle size determination of powders passing through a 75-micron sieve.
• Particle images are compared to reference circles on the graticule under a microscope.

Summary Diagram of Grid Construction

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 placed]
    C --> E[Subdivision Lines forming specified areas]
    C --> F[Open Circles of specified diameters]

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

IS 5257: General Requirements for Graticule Design

Key Specifications (Clause 2.3.1 & Table 1)

• Grid Dimensions:
  • Length = 100 units
  • Breadth = 50 ± 0.25 units
• Calibration Marks:
  • Length = 7.5 units on longer axis
  • Distance between calibration marks = 85.4 ± 0.25 units
• Ruling Lines:
  • Width ≤ 1/5 unit (max 1/500th of grid length)
  • Uniform within ±20%
• Open Circles Diameters (units ± tolerance):

Notes:

• Lengths measured between centers of ruling lines.
• Circle diameters measured between outside edges.
• Grid subdivided per Fig. 1 with specific area ratios.
• Graticule pattern includes rectangular grid, calibration marks, open and solid circles numbered 1 to 7, grid length label, and maker's info.

Summary Formula for Unit Length:

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

graph TB
    A[Rectangular Grid] --> B[Calibration Marks (7.5 units)]
    A --> C[Subdivisions per Fig.1]
    A --> D[Open Circles (7 sizes)]
    A --> E[Solid Circles (7 sizes)]
    B --> F[Distance between marks: 85.4 ±0.25 units]
    D --> G[Circle diameters with tolerances]

This ensures precise, reproducible graticule design as per IS 5257 standards.

IS 5257: Pattern of Circles and Rulings - Key Specifications

1. Graticule Pattern (Clause 2.2)

• Rectangular grid subdivided (Fig. 1)
• Two calibration marks on longer axis, ringed by two units at intersections
• 7 open circles and 7 solid circles, numbered 1 to 7
• Label: "GRID LENGTH" + actual length (mm)
• Maker's name and standard number included

2. Construction Details (Clause 2.3.1)

• Boundary lines extended by 2.5 units to cross
• Calibration marks length: 7.5 units, symmetrically placed
• Subdividing lines form areas: two each { and §, four each 34% of total grid area
• Ruling width ≤ 1/5 unit (1/500th of grid length), ±20% tolerance

3. Relative Dimensions (Table 1)

• Unit length = 1/100 of grid length
• Tolerances apply to screen and eyepiece graticules (minimum 5 microns)

Summary Formula for Unit Length:

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

Visual Concept (simplified):

graph LR
A[

IS 5257: Relative Dimensions of Grid and Circles

Key Specifications (Clause 2.3 & Table 1)

• Unit of length: 1/100 of the rectangular grid length.
• Grid length: 100 units (reference length).
• Grid breadth: 50 ± 0.25 units.
• Distance between calibration marks: 85.4 ± 0.25 units.
• Diameter of open circles (units ± tolerance):

Additional Details (Clause 2.3.1)

• Boundary lines extend 2.5 units beyond grid to intersect.
• Calibration marks on longer axis are 7.5 units long, symmetric.
• Ruling line width ≤ 1/5 unit (≤ 1/500 of grid length), consistent within ±20%.
• Measurements between centers of ruling lines; circle diameters between outer edges.

Actual Grid Dimensions (Clause 2.4)

• Grid length actual size within ±2% of marked length.
• Screen graticule grid length ≥ 106.1 mm.

Summary Diagram of Grid and Circles

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[Marks on longer axis]
    A --> F[Open Circles]
    F --> G1(Circle 1: 1.41±0.03 units)
    F --> G2(Circle 2: 2.00±0.04

IS 5257 - Dimensions of Grid (Graticule)

Key Specifications & Formulas:

• Grid length (longer side): 100 units (base unit = 1/100 of grid length)
• Grid breadth (shorter side): 50 ± 0.25 units
• Distance between calibration marks: 85.4 ± 0.25 units
• Width of ruling lines: ≤ 1/5 unit (≤ 1/500th of grid length), consistent within ±20%
• Calibration marks length: 7.5 units (on longer axis), symmetrically placed
• Boundary extension: Boundary lines extended by 2.5 units to cross each other

Diameter of Circles (units with tolerance):

Additional Notes:

• Actual longer grid length tolerance: ±2% of marked value
• Minimum length of screen graticule grid: ≥ 106.1 mm
• Dimensions measured between centres of ruling lines
• Diameter of circles measured between outside edges

Summary Formula for unit length:

[ \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 = 7.5 units length]
D[Distance Between Calibration Marks = 85.4 ± 0.25 units]
E[Circle Diameters as per Table]
A --> B
A --> C
A --> D
A --> E

This ensures precise, standardized graticule dimensions for measurement accuracy.

IS 5257 - Marking of Graticules: Key Specifications & Dimensions

1. Marking Requirements (Clause 3.1)

• Manufacturer's name, trade-mark, or identification must be marked.
• The Indian Standard number (IS 5257) must be displayed.
• Optional: Use of ISI Certification Mark governed by ISI rules for quality assurance.

2. Graticule Dimensions & Features (Clause 2.3.1 & Table 1)

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

3. Pattern Elements (Clause 2.2)

• Rectangular grid subdivided as per Fig.1.
• Two calibration marks crossing longer axis.
• Sets of 7 open and 7 solid circles numbered 1 to 7.
• Marking of "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

IS 5257 Manufacturer Identification & Standard Number Marking (Clause 3.1):

• Marking Requirements:

  • Manufacturer's name, trade-mark, or other identification.
  • Indian Standard number (IS 5257).

• ISI Certification Mark:

  • Indicates compliance with IS standards.
  • Ensures inspection, testing, and quality control.
  • License for use governed by Indian Standards Institution rules.

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

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

Summary Diagram of Graticule Construction

graph TD
  A[Rectangular Grid] --> B[Length = 100 units]
  A --> C[Breadth = 50 ± 0.25 units]
  A --> D[Calibration Marks]
  D --> E[Length = 7.5 units]
  A --> F[Circles of varying diameters]
  F --> G[1.41 to 11.31 units ± tolerances]
  A --> H[Ruling line width ≤ 1/5 unit]

Note: Manufacturer identification and IS number marking ensure traceability and quality assurance per IS 5257. The graticule dimensions are critical for accurate particle size determination.

IS 5257: References to Related Standards – Key Points

Related IS Standards for Sieving and Particle Size Determination:

Summary of Specifications for Graticules (IS 5257):

• Grid length: 100 units

• Grid breadth: 50 ± 0.25 units

• Distance between calibration marks: 85.4 ± 0.25 units

• Diameter of circles:

  • 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 lines width: ≤ 1/5 unit (1/500th of grid length), uniform 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

IS 5257 - Indian Standard Graticule (Fig. 1) Key Specifications

1. Pattern & Components (Clause 2.2)

• Rectangular grid with length = 100 units, breadth = 50 ± 0.25 units.
• Two calibration marks on the longer axis, each 7.5 units long.
• Seven open circles and seven solid circles numbered 1 to 7.
• Markings include "GRID LENGTH" with actual length in mm, maker's name, and standard number.

2. Construction Details (Clause 2.3.1)

• Grid boundary lines extended by 2.5 units to intersect.
• Distance between calibration marks: 85.4 ± 0.25 units.
• Ruling line width ≤ 1/5 unit (max 1/500th of grid length), consistent within ±20%.
• Circle diameters measured between outside edges of ruling lines.

3. Circle Diameters (Table 1)

4. Notes:

• Lengths and distances are measured center to center of ruling lines.
• Diameters are measured outside edge to outside edge.
• The graticule is printed with black rulings on a diffusing screen (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[7 Open Circles & 7 Solid Circles]
    E --> F[Diameters as per Table 1