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IS 771:2000 (Part 2) is the Indian Standard (BIS) for glazed fire-clay sanitary appliances: part-2 specific requirements of kitchen and laboratory sinks. This standard lays out the specific requirements, dimensions, and manufacturing tolerances for glazed fire-clay kitchen and laboratory sinks. MEP engineers and architects use it to ensure proper sizing, coordination with plumbing fittings, and durable performance in residential, commercial, and institutional laboratory settings.
Glazed Fire-Clay Sanitary Appliances: Part-2 Specific Requirements of Kitchen And Laboratory Sinks
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! This code must be used in conjunction with IS 771 (Part 1), which details the general requirements, material properties, and performance tests (like crazing and chemical resistance).
! Because fire-clay shrinks significantly during kiln firing, these sinks have a larger dimensional tolerance (usually ±4%) than standard vitreous china. Millwork, countertops, and casework should be templated from the actual sink delivered to the site rather than relying strictly on nominal catalog dimensions.
Covers material and performance requirements for all ceramic fixtures, including fire-clay.
BS EN 997:2018+A1:2022BSI / CEN (UK / Europe)
MediumCurrent
WC pans and WC suites with integral trap
Product-specific (WCs) but includes material requirements applicable to fire-clay.
BS EN 14688:2015BSI / CEN (UK / Europe)
MediumCurrent
Sanitary appliances. Wash basins. Functional requirements and test methods
Product-specific (wash basins) but includes material and surface quality requirements.
BS 3402:1969BSI (UK)
HighWithdrawn
Specification for quality of vitreous china sanitary appliances
Historical equivalent with a similar material-centric approach to quality.
Key Differences
≠IS 771 is a general standard for 'fire-clay' material, whereas modern international standards (EN, ASME) are typically product-specific (e.g., WC Pans, Wash Basins) and performance-based, covering various ceramic materials.
≠The definition of the ceramic body differs significantly. IS 771 allows water absorption up to 12% for fire-clay, while ASME A112.19.2 requires less than 0.5% for vitreous china, a category that often includes high-grade fire-clay products in the US market.
≠International standards like EN 997 include extensive functional performance testing (e.g., solid removal tests, flush volume, trap seal replenishment) which are not part of the general material requirements in IS 771 Part 1.
≠IS 771 prescriptively specifies a minimum glaze thickness (0.4 mm), while modern international standards focus on the performance of the glaze (imperviousness, resistance) rather than its thickness.
Key Similarities
≈Both IS 771 and international counterparts mandate a crazing resistance test, typically using an autoclave at similar pressures and durations to ensure long-term glaze durability.
≈All standards require the glazed surface to be resistant to staining and chemical attack from common household acids and alkalis, ensuring the product maintains its appearance over time.
≈Requirements for the quality of the glazed surface are similar, specifying a smooth, hard, impervious finish free from visual defects like blisters, pimples, and cracks.
≈All standards specify tolerances for warpage and key dimensions to ensure the interchangeability and correct installation of fixtures.
Parameter Comparison
Parameter
IS Value
International
Source
Water Absorption of Body
≤ 12.0% by mass
≤ 0.5% by mass (for Vitreous China)
ASME A112.19.2-2018
Crazing Resistance Test (Autoclave)
0.7 N/mm² (~7 bar) for 1 hour
100 psi (~6.9 bar) for 1 hour
ASME A112.19.2-2018
Minimum Glaze Thickness
≥ 0.4 mm
Not specified; performance-based (must be impervious)
ASME A112.19.2-2018
Warpage of Flat Surfaces
Shall not exceed 6 mm
Shall not exceed 6 mm per metre of length
ASME A112.19.2-2018
Chemical Resistance
No visible stain after testing with acid and alkali solutions
No visible change after testing with a range of chemicals
BS EN 14688:2015
Test for Ink Stain
Stain from Methylene Blue dye must be removable by water after 5 minutes
Stain shall be removable with water, or if necessary, denatured alcohol
ASME A112.19.2-2018
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Dimensional tolerance (general)± 4%
Waste hole diameter (kitchen sink)65 mm
Waste hole diameter (laboratory sink)65 mm
Typical standard length (kitchen sink)600 mm or 750 mm
What is the difference between IS 771 Part 1 and Part 2?+
Part 1 covers the overarching material properties, general requirements, and testing methods for all glazed fire-clay sanitaryware. Part 2 is strictly dedicated to the dimensions, tolerances, and specific shapes of kitchen and laboratory sinks.
Why are laboratory sinks typically specified as fire-clay?+
Glazed fire-clay is thicker and heavier than standard vitreous china, making it highly resistant to physical impact, thermal shock (from hot liquids), and corrosive laboratory chemicals.
What is the expected dimensional tolerance for these sinks?+
A tolerance of ±4% is generally allowed on the specified dimensions due to the inherent manufacturing process of fire-clay.