ISO 7174-1:1988

Overview

ISO 7174-1:1988, Furniture - Chairs - Determination of stability - Part 1: Upright chairs and stools, sets out both experimental and calculative procedures to determine the resistance of upright chairs and stools to overturning. The part excludes settees, multiple seating, swivelling or rocking chairs and applies to tilt/recline mechanisms only when used in an upright position. Part 2 of ISO 7174 covers stability when chairs are fully reclined.

This standard is aimed at manufacturers, test laboratories, designers and regulatory bodies that need repeatable, documented methods for chair stability testing and design verification.

Key Topics

• Scope and exclusions: Not applicable to sofas, multi-seat units, swivel or rocking chairs; tilt mechanisms are covered only in upright use.
• Test methods: Two compatible approaches are provided:
  • Experimental: physical application of forces to reproduce forward, rear and lateral overturning conditions.
  • Calculative: moment-based calculations using measured distances and representative seat loads where direct testing is impractical.
• Test apparatus and fixtures:
  • A rigid circular load pad (200 mm diameter) with a convex spherical face (300 mm radius) is specified for seat loading.
  • Force application devices able to apply specified forces or stepwise increases; instruments must have at least ±1 N accuracy where noted.
  • Stop blocks (taquets) to prevent sliding but permit tipping; standard height below 12 mm unless design requires higher.
• Prescribed loads and positions (examples from the standard):
  • Forward and lateral tests commonly use a 600 N vertical seat load applied 50 mm from the seat edge.
  • Rear-stability tests use a 600 N vertical load applied 175 mm forward of the seat/dorsal intersection; additional horizontal loads are applied at 300 mm above the seat or at the top edge of the backrest for back-push tests.
  • Armrest lateral checks reference 250 N and 350 N vertical loads at specified offsets from midline and armrest edges.
• Tolerances and acceptance: Forces generally to ±5% accuracy; masses to ±0.5%; dimensions to ±0.5 mm.
• Reporting: Test reports must record the standard reference, specimen details, method used (experimental or calculative), results in newtons, any overturning observed, deviations from the procedures, test lab identity and date.

Applications

• Product safety verification for upright chairs and stools during design, prototype and production stages.
• Regulatory compliance and procurement specifications where documented stability performance is required.
• Comparative testing for material or geometry changes (e.g., new leg designs or armrest configurations).
• Design validation for seating used in public, commercial and institutional environments where overturning risk must be mitigated.

Related Standards

• ISO 7170 - Furniture: elements of storage - strength and durability
• ISO 7171 - Furniture: elements of storage - stability
• ISO 7172 - Furniture - Tables - Determination of stability
• ISO 7173 - Chairs and stools - Determination of strength and durability
• ISO 7174-2 - Chairs - Determination of stability - Part 2: Chairs with tipping/recline mechanisms (fully reclined)
• ISO 8019 - Tables - Determination of strength and durability

For authoritative application and full procedural detail (diagrams, formulas and the annex chart of suggested minimum overturning forces by loaded seat height), consult the full ISO 7174-1:1988 document.