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IS 5533:1969 (Part 2) is the Indian Standard (BIS) for methods of test for strength and stability of chairs and stools, part 2: determination of stability of chairs and stools. This standard specifies the material, manufacturing, dimensional, and performance requirements for vitreous china sanitary appliances. It covers items like water closets, wash basins, and urinals, and includes key tests such as water absorption, crazing, and chemical resistance.
Methods of test for strength and stability of chairs and stools, Part 2: Determination of stability of chairs and stools
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Vitreous china is defined by its very low water absorption (<0.5%), distinguishing it from less durable earthenware or fireclay sanitaryware.
! This 1969 version is obsolete. For all new projects, refer to the comprehensive IS 2556 series which has superseded this and related standards for specific products.
! On-site inspection for visible defects like cracks, chips, and uneven glazing is crucial before installation, as these are grounds for rejection under the code.
EN 1022:2018CEN (European Committee for Standardization), European Union
MediumCurrent
Furniture — Seating — Determination of stability
Specifies methods for the determination of the stability of all types of seating for adults.
ANSI/BIFMA X5.1-2017BIFMA (Business + Institutional Furniture Manufacturers Association), USA
LowCurrent
General-Purpose Office Chairs - Tests
Includes rigorous stability tests specifically for office chairs, a subset of the IS code's scope.
ISO 7173:1989ISO (International Organization for Standardization), International
MediumWithdrawn
Furniture — Chairs and stools — Determination of strength and durability
Covered stability and strength testing for general chairs, representing an older international approach.
BS 4875-1:2001BSI (British Standards Institution), United Kingdom
MediumWithdrawn
Strength and stability of furniture. Methods for determination of strength of seating.
Provided methods for determining strength and stability for seating, now aligned with European Norms.
Key Differences
≠Test Methodology: IS 5533:1969 uses simple dead weights (kg) for loading. Modern standards like EN 1022 use specified loading pads and calibrated equipment to apply precise forces (N) at geometrically defined points.
≠Units of Measurement: The IS code uses kilograms (kg) as a unit of force, which is technically incorrect. International standards strictly use Newtons (N) to measure force, distinguishing it from mass.
≠Scope Specialization: IS 5533 is a generic standard for all chairs. The international landscape has evolved into specific standards for different chair types (e.g., BIFMA X5.1 for office chairs, EN 581 for outdoor seating) with tailored test requirements.
≠Test Loads and Precision: The loads in IS 5533 are generally lower and applied with less precision than in modern standards. For example, BIFMA X5.1 specifies complex, higher loads to simulate intensive office use, including forces to overcome caster friction.
Key Similarities
≈Fundamental Principle: All standards share the core principle of applying loads to a seated object to determine its resistance to tipping over, simulating user actions.
≈Stability Axes: Both the IS code and its international counterparts assess stability along the same fundamental axes: forward, rearward, and sideways.
≈Simulated Occupant Load: A key common step in all test procedures is the initial application of a vertical load to the seat to simulate an occupant before the stability-challenging forces are applied.
≈Test Outcome: The primary pass/fail criterion in all standards is straightforward and identical in principle: the chair must not overturn during the test.
Parameter Comparison
Parameter
IS Value
International
Source
Simulated Occupant Seat Load
60 kg
600 N
EN 1022:2018
Forward Tipping Test (Vertical Load)
20 kg at the front edge of the seat
200 N at the front loading point
EN 1022:2018
Sideways Tipping Test (Vertical Load)
20 kg on the side edge of the seat
200 N at the side loading point
EN 1022:2018
Rearward Stability Test (Office Chair)
Not specified for office chairs (20 kg on backrest for general chairs)
801 N vertical load applied to backrest
ANSI/BIFMA X5.1-2017
Unit of Force
Kilogram (kg)
Newton (N)
EN 1022:2018, ANSI/BIFMA X5.1-2017
Seat Loading Device
A rigid circular disc of 200 mm diameter
A specified seat loading pad (e.g., ~400mm width)
EN 1022:2018
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Maximum water absorption0.5 % by mass
Minimum thickness of ware6 mm
Crazing test steam pressure0.35 MN/m² (approx 3.5 kgf/cm²)
What is the maximum permissible water absorption for vitreous china sanitaryware?+
The water absorption shall not be more than 0.5 percent of the mass of the dry test piece (Clause 6.2).
How is the crazing test performed?+
A piece of the ware is subjected to steam at a pressure of 0.35 MN/m² for one hour in an autoclave. After cooling, it is inspected for any fine cracks (crazing) in the glaze (Clause 6.3).
Does this standard specify the dimensions of a wash basin?+
No, this standard covers material and quality aspects. Dimensions for specific items like wash basins are covered in other standards, such as IS 2556 (Part 4).
What is 'vitreous china'?+
It is a type of ceramic fired at high temperature to make it non-porous, defined in this standard as having a water absorption of less than 0.5%.