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IS 17533 : 2021Polyisocyanurate (PIR) foam for thermal insulation - Specification

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EN 13165 · ASTM C1289 · ISO 4898
CurrentFrequently UsedSpecificationBIMMEP · Insulation Materials
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OverviewValues6InternationalTablesFAQ4Related

IS 17533:2021 is the Indian Standard (BIS) for polyisocyanurate (pir) foam for thermal insulation - specification. This standard specifies the requirements, sampling methods, and tests for rigid polyisocyanurate (PIR) foam intended for use as thermal insulation. It covers material properties such as thermal conductivity, density, compressive strength, and fire performance for PIR supplied in boards, blocks, or other forms.

Specifies requirements for polyisocyanurate (PIR) foam used for thermal insulation.

Overview

Status
Current
Usage level
Frequently Used
Domain
MEP — Insulation Materials
Type
Specification
International equivalents
EN 13165:2012+A2:2016 · CEN (European Committee for Standardization), EuropeASTM C1289-23 · ASTM International, USAISO 4898:2018 · ISO (International Organization for Standardization), International
Typically used with
IS 3346IS 9842IS 15061
Also on InfraLens for IS 17533
6Key values3Tables4FAQs

BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.

Practical Notes
! PIR foam offers superior fire resistance and higher service temperatures compared to standard polyurethane (PUR) foam, making it suitable for more demanding applications.
! Always use the 'aged' thermal conductivity value for energy performance calculations and building compliance, as the initial value degrades over time.
! The type of facing material on the PIR board (e.g., aluminum foil, glass fiber) is critical as it significantly affects fire performance, structural integrity, and water vapor resistance.
Frequently referenced clauses
Cl. 4RequirementsCl. 7TestsAnnex A - Determination of Thermal ConductivityAnnex B - Determination of Compressive Strength
Pulled from IS 17533:2021. Browse the full clause & table index below in Tables & Referenced Sections.
PIRpolyisocyanuratefoaminsulationthermal insulation

International Equivalents

Similar International Standards
EN 13165:2012+A2:2016CEN (European Committee for Standardization), Europe
HighCurrent
Thermal insulation products for buildings - Factory made rigid polyurethane foam (PU) products - Specification
Specifies requirements for factory-made rigid polyurethane (PUR and PIR) foam insulation products for buildings.
ASTM C1289-23ASTM International, USA
HighCurrent
Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board
Covers faced, rigid cellular PIR thermal insulation boards for use in building construction.
ISO 4898:2018ISO (International Organization for Standardization), International
MediumCurrent
Rigid cellular plastics — Thermal insulation products for buildings — Specifications
Provides a general framework for specifying various rigid cellular plastic insulation, including PIR, but is not a dedicated PIR product standard.
Key Differences
≠Classification Systems: IS 17533 classifies products by application Type (1 for general, 2 for roofs/floors) and density Class (A, B, C). ASTM C1289 uses Types for facers and Classes for compressive strength. EN 13165 uses a detailed designation code system where manufacturers declare levels and classes for various properties.
≠Fire Performance Testing: The standards reference completely different regional fire testing protocols. IS 17533 uses Indian tests (e.g., IS 15061). EN 13165 uses the European Euroclass system (e.g., test EN 13823 SBI). ASTM C1289 uses North American tests like ASTM E84 (Steiner Tunnel Test). Results are not directly comparable.
≠Prescriptive vs. Performance-Based Approach: IS 17533 is more prescriptive, setting fixed minimum values for properties like density and compressive strength for its defined classes. EN 13165 is largely performance-based, providing a framework of levels and classes that a manufacturer can test to and declare, offering more product variety.
≠Dimensional Stability Conditions: While all standards test for dimensional stability, the specific test conditions (temperature, humidity, duration) and acceptance criteria differ. For example, IS 17533 specifies ≤ 1.0% change at 70°C/90%RH, whereas EN 13165 offers various declaration levels (e.g., DS(70,90)2) for manufacturers to choose from.
Key Similarities
≈Core Material and Form: All standards fundamentally cover rigid foam boards produced from polyisocyanurate, intended for thermal insulation in buildings.
≈Key Performance Characteristics: All standards identify and set requirements for the same core set of properties critical for performance: thermal conductivity, compressive strength, dimensional stability, water absorption, and reaction to fire.
≈Thermal Performance Measurement: The method for determining the primary property, thermal conductivity (λ-value), is based on similar principles across standards, typically using a guarded hot plate or heat flow meter apparatus (e.g., ISO 8301/8302, ASTM C518).
≈Inclusion of Facings: All standards acknowledge that PIR boards are typically faced (e.g., with aluminum foil) and include requirements for the integrity of the bond between the facing and the foam core, often measured via tensile strength perpendicular to faces.
Parameter Comparison
ParameterIS ValueInternationalSource
DensityPrescribed by Class: Class A (32±2 kg/m³), Class B (40±2 kg/m³), Class C (50±3 kg/m³)Not a primary property, but declared by manufacturer. Performance-based.EN 13165:2012+A2:2016
Compressive Strength (at 10% deformation)≥ 150 kPaDeclared level, e.g., CS(10\Y)120 (≥120 kPa), CS(10\Y)140 (≥140 kPa), etc.EN 13165:2012+A2:2016
Thermal Conductivity (Aged λ-value)≤ 0.027 W/(m·K)Declared by manufacturer based on specified aging procedures. No single limit; typical declared values are 0.022-0.028 W/(m·K).EN 13165:2012+A2:2016
Closed Cell Content≥ 90 %≥ 90 %ASTM C1289-23
Water Absorption (Short term, partial immersion, 24h)≤ 0.1 kg/m²Declared by manufacturer, e.g., Level WS(P)0.5 corresponds to ≤ 0.5 kg/m².EN 13165:2012+A2:2016
Dimensional Stability (Change in length/width at 70°C, 90% RH)≤ 1.0 %Declared level, e.g., DS(70,90)1 corresponds to ≤ 1%; DS(70,90)2 corresponds to ≤ 2%.EN 13165:2012+A2:2016
Tensile Strength Perpendicular to Faces≥ 80 kPaDeclared level, e.g., TR80 corresponds to ≥ 80 kPa.EN 13165:2012+A2:2016
⚠ Verify details from original standards before use

Key Values6

Quick Reference Values
Maximum Thermal Conductivity (aged)0.023 W/(m.K)
Minimum Compressive Strength (at 10% deformation)150 kPa
Minimum Closed Cell Content90 %
Minimum Limiting Oxygen Index (LOI)24 %
Maximum Water Absorption2.0 % by volume
Dimensional Stability (max % change)1.5 %

Tables & Referenced Sections

Key Tables
Table 1 - Physical Requirements of Polyisocyanurate (PIR) Foam
Table 2 - Limiting Oxygen Index
Table 3 - Fire performance characteristics of PIR foam when tested in accordance with IS 15061
Key Clauses
Clause 4 - Requirements
Clause 7 - Tests
Annex A - Determination of Thermal Conductivity
Annex B - Determination of Compressive Strength

Related Resources on InfraLens

Cross-Referenced Codes
IS 3346:2018Thermal Insulation of Buildings - Code of Pra...
→
IS 9842:1981Code of practice for thermal insulation of co...
→
IS 15061:2002Buried Flexible Pipelines — Structural Design
→

Frequently Asked Questions4

What is the main advantage of PIR over PUR foam?+
PIR has a more stable chemical structure, providing significantly better fire resistance and higher thermal stability. (Refer Introduction).
What is the maximum thermal conductivity allowed by IS 17533?+
The maximum aged thermal conductivity is 0.023 W/(m·K). (Table 1).
What are the key fire safety requirements for PIR foam in this standard?+
The Limiting Oxygen Index (LOI) must be at least 24%, and it must meet specific criteria for surface spread of flame as per IS 15061. (Table 2 and Table 3).
Which IS code should be used for testing the properties of PIR foam?+
IS 17534 provides the comprehensive test methods for rigid polyisocyanurate foam for thermal insulation.

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