Specification for protective helmets for scooter and motorcycle riders

IS 4151: Scope & Key Specifications

Scope (Clause 3.0)

• Defines test headforms for impact absorption per IS 7692:1993.
• Specifies headform sizes and masses for testing protective helmets.

Key Tables & Specifications

• Use the next smallest headform if size not listed.

Testing Device Characteristics (Clause 1.2)

Summary

• Headforms simulate human head sizes for helmet impact tests.
• Testing device parameters ensure consistent impact conditions.
• Refer IS 7692:1993 for detailed headform dimensions.

flowchart LR
    A[Test Headforms] --> B[Sizes & Masses]
    B --> C{Use next smallest if size not listed}
    A --> D[Impact Absorption Test]
    D --> E[Testing Device Specs]
    E --> F[Mass of punch: 0.3kg]
    E --> G[Drop hammer: 3kg, 1m fall]
    E --> H[Cone angle: 60°]

This concise overview covers the scope and key test headform and testing device specs from IS 4151.

IS 4151: Key References, Formulas & Tables

1. Test Headforms (Clause 2.1.5 & Table 2)

• Headform shape per IS 7692:1993.
• If size not listed, test with next smallest headform.

2. Testing Device Characteristics (Clause 1.2, Table D-1.2)

3. Test Sequence & Points of Impact (Clause 4.3, Table 3)

Summary Diagram of Test Setup

graph LR

IS 4151 - Key Definitions, Formulas, and Specifications

1. Testing Device Characteristics (Clause 1.2, Table D-1.2)

2. Test Headforms (Clause 2.1.5, Table 2)

Note: For sizes not listed, use the next smallest headform size.

3. Impact Surface Shape (Clause 9.1.1)

• Flat then hemispherical surfaces are standard for impact absorption tests.
• Headforms labeled B, B1, X, X1 are selected for specific tests involving radiation and moisture.

Summary Diagram of Testing Device Setup

graph LR
A[Drop Hammer] -->|Mass 3 kg| B[Punch Head]
B -->|Cone Angle 60°| C[Specimen]
B -->|Radius 0.5 mm| C
A -->|Height 1 m| C

This concise summary covers definitions and key parameters for IS 4151 testing devices, headforms, and impact conditions.

IS 4151: Materials and Construction – Key Specifications & Tables

1. Testing Device Characteristics (Clause 1.2, Table D-1.2)

2. Material Selection for Visor (Clause 4.6)

• Must comply with IS 9973:1981 for material criteria.

3. Test Headforms (Clause 2.1.5, Table C-2.1.5)

Note: Use next smallest size if exact size not listed.

4. Test Sequence & Points of Impact (Clause 4.3, Table C-4.3)

IS 4151: Sizes and Headforms for Helmets

Key Specifications from Clause 2.1.5 & 5.1

• Headform dimensions and shape must comply with IS 7692:1993.
• Helmets are tested on headforms matching the following sizes (mm):

• Helmets shall be manufactured for sizes:
  500, 520, 540, 560, 570, 580, 600, 620 mm (as per updated Clause 5.1).

• If a size is not listed, test with the next smallest headform.

Constructional Note

• Helmets must be fitted on the corresponding headform per Annex B procedure.

Summary Table for Headforms

Reference:

• IS 7692:1993 for detailed headform geometry above and below the reference plane.

flowchart LR
    HelmetSize["Helmet Size (mm)"]
    HeadformSize["Headform Size (mm)"]
    HelmetSize --> HeadformSize
    HeadformSize -->|Match| 500
    HeadformSize -->|Match| 

IS 4151: Key Design & Performance Requirements

1. Testing Device Characteristics (Clause 1.2, Table D-1.2)

2. Test Headforms (Clause 2.1.5, Table 2)

• Use the next smallest headform size if not listed.

3. Helmet Mass Limit (Clause 8.1)

• Maximum mass of helmet (excluding peak, visor, detachable lower face cover): 1500 g

4. Impact Testing Sequence (Clause 4.3, Table 3)

Summary Diagram of Impact Points

IS 4151: Workmanship and Finish - Key Specifications & Testing

1. Testing Device Characteristics (Clause 1.2, Table D-1)

2. Test Sequence & Points of Impact (Clause 4.3, Table 3)

3. Visor Material (Clause 6.6 & 4.6)

• Must conform to IS 9973:1981 specifications.

Summary:

• Use a 0.3 kg punch with a 60° cone angle and 0.5 mm radius.
• Drop hammer: 3 kg from 1 m height.
• Hardness of punch tip: Rockwell C 45-50.
• Test impacts on specified points with flat and hemispherical anvils under various conditions.
• Visor material per IS 9973:1981.

flowchart TD
    A[Workmanship & Finish] --> B[Testing Device Specs]
    B --> B1[Mass of Punch: 0.3 kg]
    B --> B2[Angle: 60°]
    B --> B3[Drop Hammer: 3 kg, 1 m fall]
    B --> B4

IS 4151 Key Points on Mass and Comfort

1. Mass of Test Headforms (Clause 2.1.5, Table 2)

• Use the next smallest headform size if the size is not listed.

2. Helmet Mass Limit (Clause 8.1)

• Maximum mass of helmet (without peak, visor, detachable lower face cover): 1500 g (1.5 kg)
• Lower mass helmets are preferred due to comfort and advanced materials.

3. Comfort Padding (Clauses 4.3 & 3.5)

• Padding materials: Expanded polyurethane foam, polyethylene, or similar.
• Purpose: Enhance wearer comfort.

Summary:

• Test headform mass varies by size (3.1 to 6.1 kg).
• Helmet mass must not exceed 1.5 kg (excluding accessories).
• Comfort padding must be soft foam or equivalent for user comfort.

flowchart TD
    A[Helmet Design] --> B[Mass ≤ 1.5 kg]
    A --> C[Comfort Padding]
    C --> D[Expanded Polyurethane Foam]
    C --> E[Polyethylene Foam]
    B --> F[Test Headform Mass]
    F --> G[Size A: 3.1 kg]
    F --> H[Size O: 6.1 kg]

This ensures helmets are lightweight and comfortable per IS 4151 standards.

IS 4151: Performance Tests - Key Specifications & Tables

1. Testing Device Characteristics (Clause 1.2, Table D-1.2)

2. Test Sequence & Points of Impact (Clause 4.3, Table 3)

3. Test Headforms (Clause 2.1.5, Table 2)

Note: For sizes not listed, test with the next smallest headform.

Summary Diagram: Testing

IS 4151: Marking and Labeling Key Points

1. BIS Certificate Marking (Clause 12.1.1)

• Helmets may be marked with the BIS Standard Mark.
• Details for the Standard Mark are available from the Bureau of Indian Standards.

2. Marking of Points of Impact (Clause 1.2)

• Points of impact on helmets must be marked before conditioning.
• Refer to Fig. 4 in IS 4151 for marking locations.

3. Test Headforms (Clause 2.1.5, Table 2)

• Use the next smallest headform size if the size is not listed.

4. Testing Device Specifications (Clause D-1.2)

Summary Diagram of Marking & Testing Setup

flowchart LR
    A[Helmet] --> B[Mark Points of Impact (Fig.4)]
    B --> C[Test Headform Selection]
    C --> D[Impact Testing Device]
    D --> E[Verify BIS Marking]

Note: Refer to IS 7692 for detailed headform dimensions and BIS for marking standards.

IS 4151: List of Referenced Indian Standards & Key Specifications

Referenced Indian Standards (Annex A, Clause 2)

Headform Specifications (Clause 2.1.5, Table 2)

• Use next smallest size if exact size not listed.

Additional Key Notes

• Helmets per IS 4151 are not for high-speed competitive events (Clause 1.2).
• BIS Standard Marking is optional but recommended (Clause 12.1.1).
• Retention test apparatus details corrected in Amendment No. 2 (Fig. 7).
• Impact tests use wooden headforms per IS 7692:1993.

Summary Diagram: Headform Sizes & Mass

graph LR
A[Size 500 mm] -->|Mass 3.1 kg| E[Size 540 mm]
E -->|Mass 4.1 kg| J[Size 570 mm]
J -->|Mass 4.7 kg| M[Size 600 mm]
M -->|Mass 5.6 kg| O[Size 620 mm]

This ensures standardized impact testing for helmet safety compliance.

IS 4151 – Positioning of Helmet on Headform (Clause 6.5.1, Annex B)

Key Specifications & Procedure:

• Headform Selection: Use a headform of appropriate size as per IS 7692:1993.
• Initial Placement:
  • Place helmet on the headform.
  • Apply a 50 N vertical load on the crown to seat the helmet properly.
  • Ensure the vertical median plane of helmet coincides with that of the headform.
• Field of Vision Check:
  • Front edge of helmet is placed against a gauge.
  • Check minimum angle for upward field of vision.
• Post-conditioning Positioning (Clause 1.3):
  • Tilt helmet 25 mm rearward displacement of front edge in median plane.
  • Adjust retention system under chin.
  • Tighten adjustable chin-strap fully.
• Load Application (Clause 1.2):
  • Helmet held at penetration point of vertical axis through headform’s center of gravity.
  • Load-bearing device aligned with this vertical axis.
  • Measure vertical displacement at load application point.

Summary Table:

flowchart TD
    A[Select Headform (IS 7692)] --> B[Place Helmet on Headform]
    B --> C[Apply 50 N Load on Crown]
    C --> D[Align Median Planes]
    D --> E[Check Front Edge Against Gauge]
    E --> F[Check Upward Field of Vision]
    F --> G[Tip Helmet 25 mm Rearward]
    G --> H[Adjust & Tighten Chin Strap]
    H --> I[Apply Load at Center of Gravity]
    I --> J[Measure Vertical Displacement]

This ensures consistent, repeatable helmet positioning for testing per IS 4151.

IS 4151 - Impact Absorption Test (Clause 9.1 & Annex C)

Principle (C-1.1)

• Helmet fitted on a test headform is dropped in a guided free fall.
• Impact velocity is specified.
• Acceleration vs. time is recorded when the headform hits a fixed steel anvil.
• This measures the helmet's impact absorption capacity.

Test Headforms (Clause 2.1.5 & Table C-2.1.5)

• Headform dimensions comply with IS 7692:1993.
• If size not listed, test with next smallest headform.

Key Notes:

• Impact velocity and acceleration-time data are critical for evaluation.
• Steel anvil is rigid and fixed to ensure repeatability.
• The test simulates real impact conditions to verify helmet safety.

flowchart LR
    Helmet -->|Fitted on| Headform
    Headform -->|Dropped at specified velocity| Steel_Anvil
    Steel_Anvil -->|Impact| Acceleration_Sensor
    Acceleration_Sensor -->|Records| Acceleration_vs_Time

This test ensures helmets meet safety standards by quantifying impact energy absorption.

IS 4151: Resistance to Penetration Test (Clause 9.2 & Annex D)

Key Specifications for Testing Device (Annex D - Table D-1)

Test Procedure (Clause 9.2)

• Test at two points within the helmet protection area.
• Points must be ≥ 75 mm apart and from any previous impact.
• After conditioning that yields the least satisfactory impact absorption.
• Punch head must maintain a vertical clearance of ≥ 5 mm from the headform during testing.

Summary Diagram of Test Setup:

graph TD
    A[Drop Hammer (3 kg)] -->|Falls 1 m| B[Punch Head (0.3 kg, 60° cone)]
    B -->|Impacts Helmet Surface| C[Helmet Headform]
    C -->|≥ 5 mm Clearance| D[Headform Surface]

This ensures standardized resistance to penetration for helmet safety per IS 4151.

IS 4151 Audibility Test (Clause 9.5 & Annex G) Summary

• Purpose: Test helmet's sound attenuation; sound transmission loss ≤ 10 dB over 250–2000 Hz.

Measuring Apparatus (G-1.1)

• Headform: As per IS 7692:1993 (human head shape).
• Sound Level Meter: IS 9779:1981 compliant.
• Microphone Position: At ear location (right or left).
• Weighting Network: Use Curve A (A-weighting).

Sound Source (G-1.2)

• Type: Horn as per IS 1884:1981, Type 2A.
• Sound Pressure Level: 90 to 115 dB(A).
• Position: Sound incident from back of headform.

Key Formula: Sound Transmission Loss (STL)

[ STL = L_{incident} - L_{transmitted} ]

• (L_{incident}): Sound level without helmet.
• (L_{transmitted}): Sound level with helmet on headform.

Requirement:
[ STL \leq 10 \text{ dB (250 Hz to 2000 Hz)} ]

flowchart LR
    A[Sound Source (Horn)] -->|Sound from back| B[Headform with Helmet]
    B --> C[Microphone at ear]
    C --> D[Sound Level Meter (A-weighted)]
    D --> E[Calculate STL]

This ensures helmet sound attenuation meets IS 4151 standards for user safety.