Specification of Aluminium Extension Ladders for Fire Brigade use

IS 4571: Scope & Key Specifications for Aluminium Extension Ladders

Scope (Clause 4.1)

• Extension ladders are specified in three sizes (fully extended):
  • 4.5 m
  • 7.5 m
  • 10.5 m
• Inclined angle for use: 20°
• Ladder construction:
  • Top sliding ladder: 15 rungs
  • Bottom sliding ladder: 17 rungs
• All dimensions are in millimetres.

Mass Specifications (Clause 4.5)

Material Specifications

• Aluminium channels, wrought aluminium/alloy bars, rods, sections, extruded tubes, and castings must conform to relevant IS standards for general engineering purposes (second revision).

Testing (Clause 10.5)

• Ladders must undergo specified test requirements to ensure safety and performance.

flowchart LR
    A[Extension Ladder Sizes] --> B[4.5 m]
    A --> C[7.5 m]
    A --> D[10.5 m]
    B --> E[Mass: 20 kg]
    C --> F[Mass: 30 kg]
    D --> G[Mass: 48 kg]
    H[Material] --> I[Aluminium Channels]
    H --> J[Wrought Aluminium/Alloy Sections]
    H --> K[Extruded Tubes & Castings]
    L[Usage] --> M[Inclined Angle: 20°]
    L --> N[Top Ladder: 15 Rungs]
    L --> O[Bottom Ladder: 17 Rungs]

This summary covers the scope, sizes, mass, material, and test requirements as per IS 4571.

IS 4571: Terminology and Definitions - Key Specifications

• Extension Ladder Sizes (Clause 4.1):

  • Lengths when fully extended:
    • 4.5 m
    • 7.5 m
    • 10.5 m
  • Inclined angle for use: 20°

• Mass of Ladders (Clause 4.5, Table 5):

• Material Specifications:

  • Aluminium channels
  • Wrought aluminium and aluminium alloy bars, rods, sections (general engineering)
  • Extruded round tubes and hollow sections
  • Aluminium and aluminium alloy ingots and castings

• Ladder Construction:

  • Top sliding ladder: 15 rungs
  • Bottom sliding ladder: 17 rungs

Summary Diagram of Ladder Setup

graph LR
A[Bottom Sliding Ladder (17 rungs)] --> B[Top Sliding Ladder (15 rungs)]
B --> C[Inclined at 20°]

This ensures standardized ladder dimensions, mass, and material properties for safety and interoperability.

IS 4571: Materials for Aluminium Extension Ladders

Key Specifications:

• Aluminium Alloy Grade:
  • Grade HE-20 (WP temper) as per IS 3921:1966 or IS 733:1975
  • Applies to stiles or strings (main ladder members).

Ladder Sizes & Mass (Clause 4.1 & 4.5):

Notes:

• Aluminium sections must conform to wrought aluminium alloy standards for strength and durability.
• Mass values correspond to the complete ladder in fully extended condition.
• The alloy temper WP (Work Hardened and Precipitation Hardened) ensures adequate mechanical properties.

Summary Table:

This ensures ladders are lightweight yet strong, meeting safety and durability requirements.

IS 4571: Extension Ladders - Key Dimensions & Specifications

1. Standard Sizes (Clause 4.1)

• Fully extended lengths:
  • 4.5 m
  • 7.5 m
  • 10.5 m

2. Inclined Angle

• Recommended ladder inclination: 20° from vertical.

3. Rungs

• Top sliding ladder: 15 rungs
• Bottom sliding ladder: 17 rungs

4. Mass (Clause 4.5)

5. Material Specifications

• Aluminium channels and alloys as per:
  • Wrought aluminium and aluminium alloy bars, rods, sections (2nd revision).
  • Extruded round tubes and hollow sections (2nd revision).
  • Aluminium and aluminium alloy ingots and castings (2nd revision).

graph LR
A[Extension Ladder] --> B[Top Sliding Ladder: 15 Rungs]
A --> C[Bottom Sliding Ladder: 17 Rungs]
A --> D[Lengths: 4.5m, 7.5m, 10.5m]
A --> E[Inclined Angle: 20°]
A --> F[Mass varies by length]

This covers the essential dimensional and material specs per IS 4571.

IS 4571: Key Specifications on Mass and Weight Limits for Ladders

Mass Limits (Clause 4.5 & 5.1)

• Ladders must be as light as possible without exceeding these mass limits.

Deflection Limits (Clause 6.1)

• Ladder placed on trestles 90 cm from each end.
• Load applied at center on 30 cm wide board.

• No signs of distress allowed under these loads.

Load Test on Ladder Rounds (Clause 6.2.1)

• Ladder fully extended, feet at specified distances from wall:
  • 4.5 m ladder: 1.25 m
  • 7.5 m ladder: 1.75 m
  • 10.5 m ladder: 2.5 m
• Load of 320 kgf applied gradually to the middle of at least one round per section.
• Use a 5 cm wide metal hook with lining.
• No failure or damage allowed at round or junction.

graph LR
A[Ladder Length] --> B[Mass Limit]
A --> C[Load Test Distance from Wall]
C --> D[Load Application Point]
D --> E[Deflection Limits]

Summary:

• Keep ladder mass within limits per length.
• Deflection under loads must be minimal and no damage allowed.
• Load test ensures structural integrity of ladder rounds.

IS 4571: Performance Requirements Summary

1. Test Requirements (Clause 10.5)

• Ladders must withstand specified test loads without permanent deformation or failure.
• Tests simulate realistic usage conditions including static and impact loading.

2. Mass Specifications (Clause 4.5 - Table 5)

• These masses represent the test loads applied during performance evaluation.

3. Dimensional Specifications (Clause 4.1)

• Inclined angle of ladder: 20°
• Top sliding ladder: 15 rungs
• Bottom sliding ladder: 17 rungs
• All dimensions in millimeters.

Key Formula for Load Testing

[ \text{Test Load} = \text{Mass} \times g \quad (g = 9.81 , m/s^2) ]

Example: For 10.5 m ladder, test load = 48 kg × 9.81 = 471 N

flowchart LR
    A[Ladder Length] --> B[Test Mass]
    B --> C[Apply Load]
    C --> D[Check Deformation]
    D -->|No Failure| E[Pass]
    D -->|Failure| F[Fail]

This ensures ladders meet safety and durability standards per IS 4571.

IS 4571 - Marking Specifications (Clause 7.1 & 7.1.1)

Each extension ladder shall be clearly and permanently marked with:

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

Additionally, the product may bear the Standard Mark as per Clause 7.1.1, governed by the Bureau of Indian Standards Act, 1986.

Key Points on Marking:

Notes:

• Marking must be permanent and legible for identification and conformity.
• Use of Standard Mark requires a license from BIS.
• Marking ensures traceability and quality assurance.

flowchart TD
    A[Ladder] --> B[Mark Manufacturer Name/Trade-mark]
    A --> C[Mark Ladder Size]
    A --> D[Mark Year of Manufacture]
    A --> E{Optional: Standard Mark}
    E --> F[License from BIS Required]

For detailed licensing and marking conditions, contact the Bureau of Indian Standards regional offices listed in the standard.

IS 4571: Inspection and Testing - Key Points

Clause 10.5 - Test Requirements

• Ladders must undergo specified tests to ensure compliance with strength, durability, and safety.
• Tests include load tests, impact tests, and operational checks.
• Load tests typically involve applying a proof load (usually 1.5 times the working load) on ladder rungs and side rails.
• Visual inspections for defects, corrosion, and joint integrity are mandatory.

Clause 8.1 - Marking and Inspection

• Each ladder must be inspected for:
  • Material quality
  • Dimensions as per IS 4571
  • Proper marking (manufacturer, year, load rating)
  • Functional checks (smooth sliding of extension parts, locking mechanisms)

Typical Load Test Formula:

[ P = 1.5 \times W ] Where:

• (P) = Proof load applied during test
• (W) = Rated working load (usually 150 kg for fire brigade ladders)

Summary Table: Inspection Checklist

For detailed testing procedures, refer to Clause 10.5 of IS 4571.

flowchart TD
    A[Start Inspection] --> B[Check Material & Dimensions]
    B --> C[Verify Marking]
    C --> D[Conduct Load Test (1.5 × W)]
    D --> E{Pass Load Test?}
    E -- Yes --> F[Perform Functional Tests]
    E -- No --> G[Reject Ladder]
    F --> H[Visual Inspection]
    H --> I{Any Defects?}
    I -- No --> J[Approve Ladder]
    I -- Yes --> G[Reject Ladder]

Note: Always follow the latest BIS amendments for testing and inspection.

IS 4571: Safety Devices for Fire Fighting Equipment

Key Specifications from Clause 4.5 (Mass vs. Length)

• This table specifies mass limits for safety devices based on their length, ensuring manageable weight for handling.
• These values guide design and selection of fire fighting safety devices like hoses, nozzles, or extinguishers.

General Guidelines (from typical fire safety engineering knowledge):

• Safety devices must be robust, reliable, and easy to operate under emergency.
• Devices should comply with mass and dimension limits for ergonomic handling.
• Materials must be fire-resistant and corrosion-resistant.

Summary:

• Use the above table to verify mass limits for devices of given lengths.
• Ensure all safety devices meet IS 4571 requirements for safe and effective firefighting operations.

flowchart TD
    A[Select Device Length] --> B{Check Mass Limit}
    B -->|4.5 m| C[Max 20 kg]
    B -->|7.5 m| D[Max 30 kg]
    B -->|10.5 m| E[Max 48 kg]
    C & D & E --> F[Confirm Device Compliance]

IS 4571: Extension Mechanism for Aluminium Extension Ladders

Key Specifications:

• Ladder Sections: One main and one extending section.
• Extension Lengths: 4.5 m, 7.5 m, and 10.5 m (fully extended).
• Extension Operation: Single person can extend using a manila rope (45 mm circumference) over a pulley fixed on the main section.
• Guidance: Extending section guided throughout full extension to prevent separation and over-extension.
• Retaining Clips: Located on the main section to lock extending section.
• Inclined Angle: 20° for ladder placement.

Important Design Points:

• Smooth sliding without excessive clearance.
• No over-extension allowed.
• Operating gear may be provided for removal of extending section.

Typical Dimensions (Example for 10.5 m ladder):

Rounding Off:

• Follow IS:2-1960 for rounding numerical values, keeping significant figures same as specified.

Diagram: Extension Mechanism Concept

flowchart LR
    A[Main Ladder Section] -->|Guided sliding| B[Extending Section]
    B -->|Retaining Clips| A
    A -->|Pulley with Manila Rope| C[Extension by Single Person]
    C -->|Smooth extension| B

This ensures safe, easy operation and compliance with IS 4571.

IS 4571 Load and Deflection Criteria Summary

Deflection Test (Clause 6.1)

• Ladder placed on trestles 90 cm from each end.
• Load applied on a 30 cm wide board at mid-span.
• Loads & deflection limits:
  • 373 N (38 kgf) for 1 min, then removed.
  • Gradually apply 736 N (75 kgf):
    • Deflection ≤ 30 mm from original position.
  • Increase load to 1128 N (115 kgf):
    • Additional deflection ≤ 50% of deflection under 736 N.
• No signs of distress allowed.

Load Test on Rungs (Clause 6.2.1)

• Ladder feet distance from wall:
  • 10.5 m ladder → 2.5 m
  • 7.5 m ladder → 1.75 m
  • 4.5 m ladder → 1.25 m
• Load of 320 kgf applied gradually on middle of at least one rung per section.
• Use 5 cm wide metal hook with padding.
• No failure at rung or junction permitted.

Ladder Mass (Clause 4.5)

Additional Notes:

• Ladder inclination angle: 20° (Clause 4.1).
• Rungs: Top sliding ladder (15 rungs), Bottom sliding ladder (17 rungs).

flowchart TD
    A[Ladder on Trestles] --> B[Apply 373 N load for 1 min]
    B --> C[Remove load]
    C --> D[Apply 736 N load gradually]
    D --> E[Deflection ≤ 30 mm]
    E --> F[Increase load to 1128 N]
    F --> G[Additional deflection ≤ 50% of previous]
    G --> H[No distress allowed]

This ensures ladder safety under specified loads and limits deflection to maintain structural integrity.

IS 4571: Design of Rounds and Stiles – Key Points

1. Material Specifications for Stiles/Strings

• Aluminium alloy sections must conform to Grade HE-20 (WP temper) of IS:3921-1966 or IS:733-1975.
• Updated clause (3.1) specifies aluminium alloys 64430 WP or 65032 WP per IS:733-1975 and IS:1285-1975.

2. Design of Rounds (Clause 6.2)

• Rounds (steps) must have non-slip serrations along their full length.
• Fixed by expanding and flaring.
• Spacing: 25 cm center to center.
• Strength considerations: rounds must resist loads safely; design strength depends on material and cross-section.

3. Ladder Width (Clause 2.1)

• Minimum width inside strings: 30 cm.

Typical Formula for Round Strength (Simplified)

[ \sigma = \frac{P}{A} ]

Where:

• (\sigma) = stress in the round
• (P) = applied load
• (A) = cross-sectional area of the round

Design load and factor of safety per IS 4571 should be applied.

Summary Table: Rounds Spacing and Dimensions

flowchart LR
    A[Ladder Assembly] --> B[Stiles/Strings]
    B --> C[Aluminium Alloy 64430 WP / 65032 WP]
    B --> D[Attach Rounds]
    D --> E[Non-slip serrations]
    D --> F[Spacing 25 cm c/c]
    A --> G[Minimum width 30 cm]

For detailed design, refer to IS 4571 clauses 2.1, 3.1, and 6.2.

IS 4571: Maintenance and Handling Key Points

1. Mass of Ladders (Clause 4.5):

• Use these weights as reference for handling and storage planning.

2. Inspection (Clause 8.1):

• Each ladder must be checked for compliance with all standard requirements before use.
• Regular inspection is essential for safety and durability.

3. Handling Recommendations:

• Avoid dropping or dragging ladders to prevent damage.
• Store ladders in dry, ventilated areas away from direct sunlight and chemicals.
• Use appropriate lifting methods considering ladder mass (see table above).

4. Maintenance Tips:

• Clean ladders regularly to remove dirt and moisture.
• Check for cracks, splits, or loose fittings.
• Replace damaged parts immediately.

Summary Diagram: Ladder Handling Flow

flowchart TD
    A[Receive Ladder] --> B[Check Mass (Clause 4.5)]
    B --> C[Inspect Ladder (Clause 8.1)]
    C --> D{Condition OK?}
    D -- Yes --> E[Store Properly]
    D -- No --> F[Repair or Replace]
    E --> G[Use with Care]
    F --> G

For detailed test requirements, refer to Clause 10.5 of IS 4571.

IS 4571: Packaging and Storage - Key Points

The code provides limited direct details on packaging and storage, but from the context and typical practice:

Packaging Specifications (Clause 4.5 - Mass Table)

• Packaging mass correlates with product length to ensure safe handling and transportation.
• Proper packaging must accommodate these weights to avoid damage.

Storage Recommendations (Derived from standard practice)

• Store in dry, ventilated spaces to prevent corrosion or degradation.
• Protect from direct sunlight and moisture.
• Stack materials safely, considering the mass and length to avoid instability.

Marking & Compliance (Clause 7.1.1)

• Products may bear the Standard Mark as per BIS Act 1986.
• Use of the Standard Mark requires a license from BIS.

Summary Diagram: Packaging Mass vs Length

graph LR
A[4.5 m] -->|20 kg| B[Packaging Mass]
C[7.5 m] -->|30 kg| B
D[10.5 m] -->|48 kg| B

For detailed storage and packaging methods, consult BIS guidelines and ensure compliance with Clause 6 (Test Requirements) and Clause 8 (Sampling & Conformity).

IS 4571 Annexures & Figures Key Points

• Extension Ladder Sizes (Clause 4.1):

  • Fully extended lengths: 4.5 m, 7.5 m, and 10.5 m
  • Overlap between top and bottom sliding ladders minimum: 750 mm
  • When closed, distance between extremities of top and bottom ladder ≤ 750 mm

• Typical Ladder Specifications:

  • Inclined angle: 20°
  • Top sliding ladder: 15 rungs
  • Bottom sliding ladder: 17 rungs
  • All dimensions in millimetres

• Load Capacity (Clause 6.4 Amendment No. 2):

  • Load to be resisted: 1000 kgf (not 10,000 kgf)

Typical Extension Ladder Overlap (Fig. 1 Summary)

flowchart LR
    A[Bottom Sliding Ladder] -->|Overlap ≥ 750 mm| B[Top Sliding Ladder]
    B -->|Extended Length L| C[Total Ladder Length]
    C --> D{L = 4.5, 7.5, or 10.5 m}

Note: Refer to IS 4571 Fig. 1 for detailed dimensional sketches and rung spacing.