Specification for visors for scooter helmets

IS 9973: Scope & Key Specifications

• Scope (Clause 2.0): Defines terms related to eye protectors, focusing on optical testing methods.

• Test Setup (Clause 2.1):

  • Align telescope and target on the same axis.
  • Use a parallel light beam at 4.6 ± 0.1 m distance.
  • Focus reticule and target to set zero dioptre scale.
  • Calibration allows measuring power as low as 0.01 m⁻¹ (0.01 dioptre).

• Prismatic Power Test (Clause 2.5):

  • Place visor normal to telescope axis.
  • If reticule intersection lies outside the bigger annulus image, prismatic power > 0.5 m⁻¹ (0.5 dioptre).

Summary Table: Calibration & Testing

This standard ensures precise optical calibration of eye protectors using telescope-based methods as per IS 7524 (Part II).

flowchart LR
  A[Telescope] -->|Parallel beam| B(Target)
  B --> C{Focus reticule & target}
  C --> D[Set zero dioptre scale]
  D --> E[Measure prismatic power]
  E -->|If >0.5 dioptre| F[Reject lens]
  E -->|If ≤0.5 dioptre| G[Accept lens]

IS 9973: Key Definitions & Specifications

Clause 2.0 - Definitions (Summary)

• Visor Screen: Curved transparent plastic protecting eyes and face (Clause 2.2).
• Prismatic Power: Measured by placing the visor normal to telescope axis; if reticule intersection lies outside the bigger annulus image, prismatic power > 0.5 dioptre (Clause 2.5).

Clause 2.5 - Prismatic Power Test (Table A-2 Summary)

Appendix A - Method of Test for Spherical and Cylindrical Error (Clauses 5.4.2 & 5.4.3)

• Use telescope and reticule lines to detect optical errors.
• Ensures visor meets optical clarity and distortion limits.

Notes:

• The prismatic power limit of 0.5 dioptre ensures minimal optical distortion.
• Visor screens must be transparent, curved plastic for impact and optical protection.

flowchart LR
    A[Visor Screen] --> B[Place normal to Telescope Axis]
    B --> C{Reticule Intersection}
    C -->|Inside Annulus| D[Prismatic Power ≤ 0.5 D]
    C -->|Outside Annulus| E[Prismatic Power > 0.5 D]

For detailed testing procedures and optical limits, refer to Appendix A of IS 9973.

IS 9973: Material Requirements - Key Points

IS 9973 mainly covers optical requirements for materials, especially glass, with specific clauses on testing methods and quality criteria.

Key Specifications:

• Light Transmission (Clause 5.4.5):

  • Minimum light transmission = 80%
  • Tested as per Appendix G of IS 7569-1975

• Optical Requirements (Clause 5.4):

  • Materials should meet specified optical clarity and error limits.
  • Tests for spherical and cylindrical errors are detailed in Appendix A (Clauses 5.4.2 & 5.4.3).

Testing Methods:

Summary:

• Use Appendix A for error measurement methods.
• Use Appendix G of IS 7569-1975 for light transmission testing.
• Ensure materials meet ≥ 80% light transmission for optical clarity.

flowchart TD
    A[Material Sample] --> B{Test Type}
    B -->|Spherical/Cylindrical Error| C[Appendix A Method]
    B -->|Light Transmission| D[Appendix G, IS 7569-1975]
    C --> E[Check Error Limits]
    D --> F[Check ≥ 80% Transmission]
    E & F --> G[Material Pass/Fail]

This ensures material optical quality complies with IS 9973 standards.

IS 9973 (1981) primarily specifies visor requirements for scooter helmets, focusing on material and performance criteria rather than structural design formulas.

Key Specifications for Design and Construction:

• Light Transmission: Minimum 80% as per Appendix G of IS 7569-1975.
• Material: Clear, impact-resistant visor material to protect from wind, insects, and obstacles.
• Testing: Visors must comply with optical clarity and mechanical strength tests.

Relevant IS Code References:

Notes:

• No structural design formulas are provided in IS 9973.
• For helmet design, refer to IS 4151-1982.
• Visor design focuses on optical clarity and impact resistance.

flowchart TD
    A[Helmet] --> B[Visor]
    B --> C{Tests}
    C --> D[Light Transmission ≥ 80%]
    C --> E[Impact Resistance]
    C --> F[Optical Clarity]

For structural design of helmets, consult IS 4151 and related standards. IS 9973 is a performance standard for visors only.

IS 9973: Performance Requirements (Optical)

• Light Transmission (Clause 5.4.5):

  • Minimum 80% light transmission as per test method in Appendix G of IS 7569-1975.

• Optical Error Testing (Clause 5.4.2 & Appendix A):

  • Spherical and cylindrical errors must be tested using the method in Appendix A.
  • These errors relate to the optical clarity and distortion limits permissible in the material.

Key Specification Summary

Notes:

• Light transmission ensures adequate visibility through the material.
• Spherical and cylindrical error tests ensure minimal distortion.

If you need formulas or detailed test procedures, refer to Appendix G of IS 7569-1975 and Appendix A of IS 9973 respectively.

flowchart LR
    A[Material Sample] --> B[Test for Light Transmission]
    B -->|≥ 80%| C[Pass]
    B -->|< 80%| D[Fail]
    A --> E[Test for Optical Errors]
    E --> F[Spherical Error Check]
    E --> G[Cylindrical Error Check]
    F & G --> H[Within Limits?]
    H -->|Yes| C
    H -->|No| D

IS 9973 – Workmanship and Finish: Key Points

1. Visor Optical Quality (Clause 6.1)

• Visor must be optically clear.
• Free from:
  • Surface imperfections
  • Scratches
  • Bubbles
  • Visual irregularities
• Edges must be smooth, burr-free, and without protrusions.

2. Field of Vision (Clause 5.5.1)

• Visor shall comply with field of vision requirements as per IS 4151-1982 (Industrial Safety Helmets).
• Ensures adequate peripheral and frontal visibility.

3. Light Transmission (Clause 5.4.5)

• Minimum light transmission: 80%.
• Tested as per Appendix G of IS 7569-1975.

4. Testing for Optical Errors (Appendix A)

• Method for spherical and cylindrical error testing of visor lenses.
• Ensures no distortion affecting wearer’s vision.

Summary Table: Workmanship & Finish Requirements

flowchart TD
    A[Visor Workmanship] --> B[Optically Clear]
    A --> C[No Surface Defects]
    A --> D[Edges Smooth & Burr-free]
    A --> E[Light Transmission ≥ 80%]
    A --> F[Field of Vision per IS 4151]
    A --> G[Test for Optical Errors]

This ensures safety helmets' visors meet visual clarity and durability standards for effective protection.

IS 9973: Mass Limitations for Visors

• Maximum Mass: The complete visor shall not exceed 350 g (Clause 7.1).
• If mass > 350 g, the exact mass (rounded to nearest 10 g) must be labeled on the visor.

Summary Table:

Additional Relevant Specifications:

• Flammability (IS 2925:1975, Appendix F): Burning rate ≤ 3 cm/min.
• Light Transmission (IS 7569:1975, Appendix G): Minimum 80%.

flowchart LR
    A[Complete Visor Mass] -->|≤ 350 g| B[No Label Required]
    A -->|> 350 g| C[Label Mass (nearest 10 g)]

This ensures safety and user awareness about visor weight per IS 9973 standards.

IS 9973 - Instructions for Use and Maintenance of Scooter Helmet Visors

Key Specifications (Clause 7.1 & 8.1)

• Mass Limit: Complete visor mass ≤ 350 g. If >350 g, label must show mass rounded to nearest 10 g.
• Cleaning Instructions:
  • Avoid scratches and dirt accumulation on visor screen.
  • Do NOT use organic solvents (metal polish, wax, polishes) for cleaning.
  • Use a soft cloth to gently wipe dust and dirt.

Summary Table for Labeling and Maintenance

Maintenance Tips:

• Regularly clean with a soft cloth.
• Store visor to avoid scratches.
• Avoid chemical cleaners that degrade visor clarity.

flowchart TD
    A[Visor Usage] --> B{Mass ≤ 350 g?}
    B -- Yes --> C[No mass label needed]
    B -- No --> D[Label mass rounded to 10 g]
    A --> E[Maintenance]
    E --> F[Use soft cloth]
    E --> G[Avoid organic solvents]
    E --> H[Prevent scratches and dirt]

This ensures visor longevity and clear vision per IS 9973 standards.

IS 9973 - Marking and Labeling Key Points

• Marking on Visor (Clause 9.1):
  Each visor must be marked with:

  • Manufacturer's name or trade-mark
  • Year of manufacture

• ISI Certification Mark (Clause 9.1.1):

  • Optional on visors
  • Use governed by Indian Standards Institution (Certification Marks) Act
  • Indicates compliance with IS 9973 under ISI supervision and quality control

• Target Plate Specifications (Clause A-1.2.1):

  • Black plate with cut-out pattern per IS 7524 (Part II)-1980
  • Bars width: 2.0 mm
  • Larger annulus diameter: 46 mm with aperture 0.6 mm
  • Smaller annulus diameter: 23 mm
  • Central aperture diameter: 0.6 mm
  • Mounted on glass plate

• Flammability (Clause 5.3):

  • Burning rate ≤ 3 cm/min (tested per Appendix F of IS 2925-1975)

Summary Table for Marking

flowchart TD
    A[Visor] --> B[Mark Manufacturer Name & Year]
    A --> C{Optional}
    C --> D[ISI Certification Mark]
    A --> E[Target Plate per IS 7524]
    A --> F[Flammability Test ≤ 3 cm/min]

This ensures traceability, quality assurance, and safety compliance per IS 9973.

IS 9973 Optical Testing: Key Methods & Specifications

Calibration Setup (Clause 2.1, A-2.1)

• Distance: Telescope and target separated by 4.6 ± 0.1 m
• Alignment: Telescope axis aligned with optical system axis
• Illumination: Trans-illuminate target with a parallel beam of adjustable light intensity
• Focus: Adjust telescope reticule and target to get a clear image; set this as zero dioptre (0 m⁻¹)
• Sensitivity: Telescope focussing calibrated to measure 0.01 m⁻¹ power increments

Testing Procedure (Clause 2.2, A-2.2)

• Insert standard lenses of ascending refractive powers normal to telescope axis
• Adjust telescope focus for each lens to get a clear image
• Mark corresponding dioptre scale readings for each refractive power

Optical Error Measurement (Clause 5.4.2 & Appendix A)

• Use the above calibration and lens insertion method to determine:
  • Spherical errors (uniform refractive power)
  • Cylindrical errors (astigmatism components)

Summary Table for Calibration

flowchart LR
    A[Telescope + Optical System] -->|Align on same axis| B(Target)
    B -->|Trans-illuminate with parallel beam| C[Adjust distance 4.6 ± 0.1 m]
    C --> D[Focus reticule & target → Zero dioptre]
    D --> E[Insert standard lenses in ascending power]
    E --> F[Adjust telescope focus]
    F --> G[Mark dioptre scale for each lens]
    G --> H[Calculate spherical & cylindrical errors]

This method ensures precise optical calibration and error measurement per IS 9973 requirements.

IS 9973 - Flammability Test Method Summary

• Reference for Flammability: Appendix F of IS 2925-1975*
• Key Specification:
  • Rate of Burning ≤ 3 cm/minute
    This means the material under test should not burn faster than 3 centimeters per minute when subjected to the specified flame test.

Flammability Test Procedure (as per IS 2925-1975, Appendix F)

• A specimen is exposed to a standard flame for a fixed duration.
• The length of the burnt portion is measured.
• The rate of burning is calculated by:

[ \text{Rate of Burning} = \frac{\text{Length of burnt specimen (cm)}}{\text{Time of exposure (minutes)}} ]

• The material passes if Rate of Burning ≤ 3 cm/min.

Additional Related Specifications (for clarity):

flowchart LR
    A[Start Test] --> B[Expose specimen to flame]
    B --> C[Measure burnt length]
    C --> D[Calculate rate of burning]
    D --> E{Is rate ≤ 3 cm/min?}
    E -- Yes --> F[Pass]
    E -- No --> G[Fail]

Note: For detailed apparatus and exact procedure, consult Appendix F of IS 2925-1975.

IS 9973 - Light Transmission Test Method (Clause 5.4.5)

• Standard Referenced: Appendix G of IS 7569:1975 (Method for Light Transmission & Diffuse Transmittance tests).
• Minimum Light Transmission: ≥ 80%
• Maximum Diffuse Transmittance: ≤ 5% (Clause 5.4.4)

Test Method Summary (from IS 7569:1975 Appendix G)

• Use a spectrophotometer or photometer to measure the percentage of visible light transmitted through the lens or eye protector.
• Measure total light transmission and diffuse transmittance separately.
• The sample is placed normal to the incident light beam.
• Diffuse transmittance is the scattered light component; total transmittance includes direct + diffuse.

Key Specifications:

Practical Notes:

• Ensure lenses are clean and free from scratches before testing.
• Calibration of photometric equipment is essential for accuracy.
• Measurements are typically done in the visible spectrum (400-700 nm).

flowchart LR
    A[Light Source] --> B[Sample Lens]
    B --> C[Photometer]
    C --> D{Measure}
    D -->|Total Transmission| E[≥ 80%]
    D -->|Diffuse Transmission| F[≤ 5%]

This ensures optical clarity and safety for eye protectors per IS 9973.