Adjustable metal chairs for the use of typists and operators in telephone exchanges-Specification

IS 5416 Part 1 - Scope & Key Specifications Summary

Scope:

• Applies to strength testing of chairs and stools.
• Includes timber products moisture content control:
  • Moisture content must be 12-15% (checked by electric moisture meter).
  • If higher, dry in warm ventilated room until within limits.
• Conditioning/testing atmosphere:
  • Temperature: 27 ± 3°C
  • Relative Humidity: 50 ± 5%

Sampling & Permissible Defects (Clause 4.3 - Table 4)

Test Types & Purposes (Clause 3.2 - Table 1)

IS 5416 Part 1 - Definitions & Key Specifications Summary

1. Definitions

• Refer to IS 4415-1967 for all definitions related to furniture testing (Clause 2.1).

2. Test Purposes (Clause 3.2, Table 1)

• Tests include static load, fatigue, impact, wear, and drop tests.
• Primary purposes: strength, durability, impact resistance, handling strength, service wear.
• Secondary purposes: damage initiation, propagation, residual strength, acceptable misuse.

3. Test Loads & Levels (Clause 3.2, Table 2)

• Test levels 1 to 5 indicate increasing severity.
• Example loads at Level 3:
  • Seat static load: 1600 N
  • Back static load: 760 N per pad
  • Arm sideways load: 600 N
  • Seat fatigue cycles: 50,000
  • Seat impact drop height: 240 mm
• Drop test heights vary by chair type and leg length (75-900 mm).

4. Application of Test Levels (Clause 3.2, Table 3)

• Domestic chairs typically tested at Levels 1-3.
• Institutional and hospital furniture require Levels 4-5.
• Folding garden/camping chairs at Levels 2-3.

Example: Seat Static Load Test Levels (N)

flowchart TD
    A[Definitions] --> B[IS 4415-1967]
    B --> C[Test Purposes]
    C --> D[Static Load]
    C --> E[Fatigue]
    C --> F[Impact]
    C --> G[Wear]
    C --> H[Drop Test]
    D --> I[Test Loads & Levels]
    I --> J[Level 1 to 5]
    J --> K[Application by Furniture Type]

For detailed load values and test cycles, refer to IS 5416 Part 1 Table 2 & Appendix A.

IS 5416 Part 1: Principle and Purpose of Tests

Key Points from Clause 3.2 & 3.2.1, 3.2.3

• Purpose: Evaluate static strength, fatigue durability, impact resistance, and residual strength under occasional high loads.
• Test Types:
  • Static Tests: Assess strength under high, slow-applied loads (Clause 3.2.1).
  • Fatigue Tests: Evaluate durability under repeated loading.
  • Impact Tests: Assess strength under rapid, sudden loads (Clause 3.2.3).

Table 1: Test Sequence & Purpose (Summary)

Severity Grading (Table 3 Reference)

• Load magnitude and number of load cycles are varied to grade test severity.

Summary Formula (Static Load Test Concept)

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

Where:

• (\sigma) = Stress in the component
• (P) = Applied static load (from test specification)
• (A) = Cross-sectional area resisting load

flowchart LR
    A[Static Tests] --> B[Basic Strength & Damage Initiation]
    A --> C[Fatigue Tests]
    C --> D[Service Durability & Damage Propagation]
    A --> E[Impact Tests]
    E --> F[Impact Strength]
    A --> G[Handling & Residual Strength Tests]

Use Table 2 (IS 5416 Part 1) for exact test loads and Table 3 for load application cycles.

IS 5416 Part 1: General Requirements for Testing

Sampling & Inspection (Clause 4.3)

• Samples must be randomly drawn from the lot.
• Timber parts: moisture content 12–15% checked via electric moisture meter.
• Conditioning atmosphere: 27 ± 3°C, 50 ± 5% RH.

Test Sequences & Purposes (Clause 3.2, Table 1)

Summary

• Follow Table 4 for sampling size & acceptance.

IS 5416 Part 1: Requirements for Tests

1. Test Sequence & Purpose (Table 1)

2. Sampling & Acceptance Criteria (Table 4)

3. Conditioning & Moisture Content

• Moisture content for timber parts: 12% to

IS 5416 Part 1: Inspection and Conditioning of Articles

Key Specifications & Formulas:

• Conditioning Time (Clause 5.2):

  • Articles (e.g., glued joints in timber/plastics) must be aged ≥ 4 weeks under normal conditions before testing to ensure full strength.

• Moisture Content for Timber Parts:

  • Use an electric moisture meter.
  • Moisture content must be 12% to 15%.
  • If above 15%, dry in a warm, ventilated room until within range.

• Standard Conditioning Atmosphere:

  • Temperature: 27 ± 3°C
  • Relative Humidity: 50 ± 5%

• Sampling & Permissible Defectives (Clause 4.3, Table 4):

• Post-Test Inspection (Clause 6.2):
  • Thoroughly inspect articles.
  • Note any defects or changes since initial inspection.
  • Record flexibility quotient and any non-functional damage.

flowchart TD
    A[Manufacture] --> B[Conditioning ≥ 4 weeks]
    B --> C[Moisture Check (12-15%)]
    C --> D{Moisture OK?}
    D -- Yes --> E[Standard Atmosphere Conditioning]
    D -- No --> F[Dry in Warm Ventilated Room]
    F --> C
    E --> G[Testing]
    G --> H[Post-Test Inspection]
    H --> I[Record Defects & Changes]

This ensures reliable, repeatable test results per IS 5416 Part 1.

IS 5416 Part 1 (1988) — Test Apparatus & Loading Pads

Key Specifications:

• Back Loading Pad (Clause 7.8)

  • Rigid rectangular block
  • Dimensions: 200 mm height × 250 mm width
  • Face: Convex cylindrical curvature radius 450 mm
  • Front edges: Rounded with 12 mm radius

• Local Loading Pad (Clause 7.10)

  • Rigid cylindrical object
  • Diameter: 100 mm
  • Flat face with 12 mm radius on front edge

• Seat Loading Pad (Clause 7.6)

  • Naturalistically shaped rigid indentor (complex shape)
  • Defined by existing moulds, not by drawing

Loading Details (Clause 9.1.1):

• Seat Static Load Test:
  • Mount seat loading pad on seat plane at:
    • Seat loading point (Clause 8)
    • 100 mm back from front edge
  • Apply downward force ( V_s ) (from Table 2) 10 times

Summary Table (Dimensions):

flowchart LR
    A[Test Apparatus] --> B[Back Loading Pad]
    B -->|Dimensions| B1[200mm x 250mm]
    B -->|Curvature| B2[450mm radius convex]
    B -->|Edges| B3[12mm radius]

    A --> C[Local Loading Pad]
    C -->|Diameter| C1[100mm]
    C -->|Edge Radius| C2[12mm]

    A --> D[Seat Loading Pad]
    D -->|Shape| D1[Complex moulded shape]

This setup ensures standardized load application for furniture strength testing per IS 5416

IS 5416 Part 1 (1988) – Determination of Seat and Back Loading Points

Key Specifications & Setup:

• Back Loading Pad (Clause 7.8):

  • Rigid rectangular pad
  • Height = 200 mm, Width = 250 mm
  • Convex cylindrical curvature radius = 450 mm (across width)
  • Front edges rounded with radius = 12 mm

• Loading Point Template (Clause 7.3):

  • Two shaped members joined by a pivot
  • Positioned at 90° angle (see Fig. 1)
  • Seat loading arm mass = 20 kg applied at seat loading point
  • Template contours designed to sink into upholstery for realistic load distribution

Procedure (Clause 8.1):

• Place template on chair with load at seat loading point on chair centerline, as far rearward as possible.
• Push back loading portion into chair back to lever seat portion forward.
• Adjust until template shape matches chair contours.
• Mark seat and back loading points from template.

Load Application:

• Seat load (A) and back load (B) applied at marked points.
• For stools, seat load (C) applied similarly.

Summary Table of Dimensions:

flowchart LR
  A[Place template on chair seat] --> B[Apply 20 kg load at seat loading point]
  B --> C[Push back loading pad into chair back]
  C --> D[Adjust until template fits chair contours]
  D --> E[Mark seat and back loading points]
  E --> F[Apply static load tests as per Clause 9.1]

This method ensures accurate positioning of load points for static load testing of chairs and stools per IS 5416 Part 1.

IS 5416 Part 1: Key Test Methods & Specifications

1. Test Types & Purposes (Clause 3.2, Table 1)

2. Sampling & Acceptance Criteria (Clause 4.3, Table 4)

3. Conditioning Requirements

• Moisture content for timber parts: 12–15% (checked with electric moisture meter)
• Standard atmosphere for testing:

IS 5416 Part 1: Test Levels & Load Specifications Summary

1. Test Purpose & Sequence (Table 1)

2. Test Loads (Table 2)

Note: Some tests not applicable at all levels.

3. Application of Test Levels (Table 3)

| Furniture Use | Test Level Recommended

IS 5416 Part 1 - Test Report: Key Specifications & Tables

1. Test Report Must Include (Clause 11.1):

• Article details tested
• Test level applied
• Defects before and after testing
• Additional requirements (Clause 9.1.2):
  • Flexibility quotient ≤ 0.0008 × Hg (Hg = seat height)
  • Back deflection ≤ 100 mm (for all-foam chairs)
  • Back force ≥ 410 N applied
  • Compliance with product specs

2. Purpose & Sequence of Tests (Clause 3.2, Table 1):

3. Loading Severity (Clause 3.2):

• Load magnitude and number of cycles vary to grade severity.
• Tests assess:
  • Static strength & initial damage
  • Fatigue strength & damage propagation
  • Residual strength after misuse

4. Flexibility Quotient Formula (Clause 9.1.2):

[ \text{Flexibility Quot