Methods of test for strength and stability of settees and benches, Part 2: Stability
1989 Edition

Overview of Scope and Key Provisions

Scope (Clause 2.0):
Specifies the standard’s applicability to seating furniture and details the test methods and load application processes.

Load Application Essentials (Clauses 4.1 & 4.3)

• Load Placement: Forces are applied at designated points on seating units.
• Template Positioning:
  • Template arranged at a right angle (90°) (Fig. 3).
  • Positioned on the furniture as illustrated in Fig. 2.
  • Loading points for seat and back (A, B, C) are marked in millimeters.

Representative Loading Points (From Template Fig. 1)

Test Documentation Requirements (Clause 8.1)

• Details of the tested furniture.
• Indication of overturning occurrence.
• Recording any procedural deviations.

Additional Remarks

• The standard mark signifies conformity and quality assurance under BIS.
• Indian Standards undergo periodic reviews and updates.

flowchart TD
    A[Place Template at 90°] --> B[Set on Bench]
    B --> C[Mark Load Points A, B, C]
    C --> D[Apply Specified Loads]
    D --> E[Conduct Stability Test]
    E --> F[Compile Test Report]

Refer to Figures 1, 2, and 3 in IS 12674 Part 2:1989 for precise dimensions and detailed procedures.

Definitions and Scope Summary (IS 12674 Part 2)

• Scope (Clause 1.1):
  Describes the procedure to evaluate the stability of settees and benches designed for two to four occupants.

• Definitions (Clause 2.0):
  Clarifies terminology related to load application points and stability assessments.

• Load Application Details (Clauses 4.1 & 4.3):

  • Loads are applied at precise points identified using a template set perpendicularly (90°) (Fig. 1).
  • The template aids in accurately marking seat load points (A & C) and back load point (B) on the furniture.
  • All measurements are specified in millimeters.

Essential Load Points for Stability Testing:

Template Utilization Illustration:

graph LR
    A[Template] -->|Set at 90°| B[Mark Load Points]
    B --> C{Load Categories}
    C -->|A| D[Seat Load - Settees]
    C -->|B| E[Back Load]
    C -->|C| F[Seat Load - Benches]

This procedure ensures uniform and reproducible load placements for stability testing as per IS 12674 Part 2.

General Testing Guidelines (IS 12674 Part 2)

Key Clauses Summary:

• Clause 2.1:

  • Objective: Confirm the furniture’s capacity to resist overturning.

• Clauses 3 & 7.1:

  • Pass criteria:
    • Furniture remains stable without overturning.
    • Compliance with product standard requirements.

• Clause 4.1:

  • Defines the method of load/force application during tests (detailed in the standard).

• Clause 8.1 (Test Reporting):
  Report must detail:

  • Tested article specifics.
  • Occurrence of overturning.
  • Any deviations from the prescribed testing method.

Acceptance Criteria Summary

Additional Notes:

• Possession of the Standard Mark confirms compliance with BIS quality norms.
• Testing ensures the furniture’s safety against tipping under defined loads.
• Strict adherence to load application procedures is essential for valid outcomes.

flowchart TD
    A[Prepare Test Setup] --> B[Apply Specified Loads (Clause 4.1)]
    B --> C{Does Furniture Overturn?}
    C -- No --> D[Verify Product Specifications]
    C -- Yes --> E[Fail the Test]
    D -- Meets Specs --> F[Pass the Test]
    D -- Does Not Meet Specs --> E

Refer to the complete IS 12674 Part 2 for detailed load application and product-specific criteria.

Equipment and Setup Specifications (IS 12674 Part 2)

1. Load Measurement Precision (Clause 3.1.1)

• All applied loads must be measured with an accuracy of ±5%.
• For practical understanding:
  [ 10 \text{ Newtons} \approx 1 \text{ kilogram-force} ]

2. Test Configuration (Clause 4.3)

• Employ a template fixed at a 90° angle to mark the loading spots (Fig. 1).
• Position the test specimen according to Fig. 2.
• Mark points A, B, and C representing:
  • A: Seat load for settees
  • B: Backrest load
  • C: Seat load for benches

3. Overturning Resistance Evaluation (Clause 2.1)

• The testing procedure assesses the furniture’s capacity to withstand tipping forces.

Load Points and Setup Summary

Template Setup Diagram (Simplified)

graph LR
  Template["90° Template"] -->|Mark Load Points| Bench["Test Bench"]
  Bench --> LoadA["Load A (Seat - settees)"]
  Bench --> LoadB["Load B (Backrest)"]
  Bench --> LoadC["Load C (Seat - benches)"]

Refer to Figures 1 and 2 of IS 12674 Part 2 for exact dimensions and layout.

Method to Identify Seat Loading Points (IS 12674 Part 2)

Specifications:

• Local Loading Pad: A rigid cylindrical pad with a diameter of 100 mm and a flat face featuring a 12 mm radius on the front edge (Clause 4.6).
• Pads must allow vertical pivoting; horizontal pivot allowed if design permits.

Loading Point Template (Clause 4.3):

• Comprises two shaped members connected via a pivot, forming a 90° angle.
• Template weight: 20 kg, applied through the seat loading area.
• Designed to slightly depress upholstery under moderate load to replicate real seating pressure.

Procedure:

1. Place the template along the seat’s centerline, as far towards the rear as possible.
2. Apply load, pressing the back portion against the backrest and levering the seat portion forward.
3. Adjust the template to conform to the seat contour.
4. Mark the seat loading point.
5. Repeat for additional seats.
6. Position the template at 90° on a bench using these points.
7. Mark final load points from the template.

Conceptual Diagram:

graph LR
A[20 kg Loading Arm] -->|Applied Load| B(Loading Point Template)
B --> C{Pivot Joint}
C --> D[Two Members at 90°]
D --> E[Template Sinks into Upholstery]
E --> F[Mark Load Points on Seat]

This process ensures precise identification of seat loading points for testing durability and comfort.

Stability Assessment Procedures for Settees and Benches (IS 12674 Part 2)

Core Principle:

• Stability is defined as the furniture’s capacity to resist tipping (Clause 2.1).

Testing Methodology (Clause 1.1):

• Applies to seating for 2 to 4 persons.
• Stability is evaluated by exerting forces and moments to simulate overturning.

Typical Stability Calculation:

1. Apply a horizontal force (F) at a height (h) from the floor, usually at seat or backrest height.
2. Compute the overturning moment:
   [ M_o = F \times h ]
3. Determine the restoring moment caused by the weight (W) of furniture and occupants acting at center of gravity distance (d) from pivot: [ M_r = W \times d ]
4. Furniture is stable if:
   [ M_r \geq M_o ]

Parameters Summary:

Summary:

• Confirm resistance against overturning moments by applying lateral forces.
• Measure weight and CG position to calculate restoring moments.
• Stability testing ensures safety from tipping hazards.

graph LR
A[Applied Force (F)] --> B[Calculate Overturning Moment (M_o = F × h)]
C[Weight (W)] --> D[Calculate Restoring Moment (M_r = W × d)]
B --> E{Is M_r ≥ M_o?}
E -- Yes --> F[Stable]
E -- No --> G[Unstable]

Refer to IS 12674 Part 2 for comprehensive test setups and force values.

Guidance on Result Interpretation (IS 12674 Part 2)

Forces and Positions (Clause 4.5)

• Vertical seat force: 250 N applied 100 mm lateral to the fore-aft centerline and 175–250 mm forward from rear seat edge.
• Vertical armrest force: 350 N applied 37.5 mm inside the armrest’s outer edge at the most critical point.
• Horizontal armrest force: 20 N applied outward at the armrest’s upper surface, aligned with the vertical force side where stops are placed.

Test Setup (Clause 4.3 & Fig. 3)

• Loading template held at 90°.
• Mark loading points as per Fig. 3 (scale: 20 mm squares).
• Position furniture with stops against legs/base on one side.

Result Interpretation (Clauses 7 & 8.1)

• Reports must include:
  • Details of the tested article.
  • Indication of overturning occurrence.
  • Any procedural deviations.
• Assess structural soundness under load.
• Check for permanent deformation, failure, or instability.

Forces Summary

Loading Positions Diagram

graph LR
    A[Seat Rear Edge] -->|175-250 mm| B(Vertical Seat Load: 250 N)
    B --> C[100 mm lateral to centerline]
    D[Armrest Outer Edge] -->|37.5 mm inside| E(Vertical Arm Load: 350 N)
    E --> F(Horizontal Arm Load: 20 N outward)

Ensure that test setups and force applications strictly comply with IS 12674 Part 2 to validate results.

Test Report Essentials (IS 12674 Part 2, Clause 8.1)

The test report must document:

• a) Article Identification: Description and unique identification of the tested seating unit.
• b) Overturning Outcome: Whether the item tipped during testing (as defined in Clause 2.1).
• c) Deviations: Any departures from standard procedures must be noted.

Pass/Fail Conditions (Clause 7.1)

• Furniture passes if:
  • It remains upright throughout testing.
  • It meets all relevant product specification criteria.

Test Report Content Summary

Additional Information

• Use of the Standard Mark is governed by BIS regulations under the Bureau of Indian Standards Act, 1986.
• Ongoing quality control and inspections are mandatory for products bearing the Standard Mark.
• Reference the latest standard amendments.

flowchart TD
    A[Begin Testing] --> B{Did Furniture Overturn?}
    B -- No --> C[Verify Against Specifications]
    B -- Yes --> D[Fail Test]
    C -- Complies --> E[Pass Test]
    C -- Does Not Comply --> D

This illustrates the decision flow based on overturning occurrence and compliance.