Overview
ISO 29768:2022 - Thermal insulating products for building applications - Determination of linear dimensions of test specimens is an ISO standard that defines how to measure the linear dimensions (length, width, thickness) of test specimens taken from thermal insulating materials. It specifies the characteristics and selection of measuring equipment, measurement procedures, environmental conditioning (including tropical climate options), rounding and reporting rules, and minimum measurement locations to ensure repeatable, accurate linear dimension data for laboratory testing and product assessment.
Keywords: ISO 29768:2022, thermal insulating products, linear dimensions, test specimens, measuring equipment
Key Topics
- Scope and principle
- Measures linear dimensions of specimens using apparatus that delivers the required accuracy.
- Approved measuring equipment and accuracy
- Dial gauge: readings to 0.05 mm; measuring pressure ≤ 1 kPa; mean rounded to 0.1 mm.
- Micrometer: readings to 0.05 mm; must include a surface-contact device (example: 10 cm aluminium plate with ~50 Pa pressure); mean rounded to 0.1 mm.
- Sliding caliper: readings to 0.1 mm; must avoid specimen deformation; mean rounded to 0.2 mm.
- Metal rule / tape: readings to 0.5 mm; mean rounded to 1 mm.
- Selection tables
- Tables in the standard guide choice of instrument by required maximum permissible error (mm or %) and by specimen size.
- Measurement procedure
- At least two widely separated measurement locations per specimen; median-of-three readings may be used per location.
- Measurements made with and without specimen where applicable (dial gauge, micrometer) to obtain differential reading.
- Test conditions and conditioning
- Follow relevant product/test method standards. Optional tropical conditioning: (27 ± 2) °C and (65 ± 5) % RH when relevant.
- Reporting
- Test report content follows the relevant test method standard and must note conditioning/testing climate if tropical conditions were used.
Applications and Users
- Practical uses:
- Quality control and dimensional verification of thermal insulating materials prior to thermal performance tests.
- Preparation of specimens for standardized thermal tests (conductivity, thickness-dependent properties).
- Ensuring traceable, reproducible dimension data for product certification and compliance.
- Who uses it:
- Test laboratories, manufacturers of thermal insulation, product certification bodies, building material specifiers, and standards writers.
Related Standards
- ISO 29465 - Determination of length and width (full-size products)
- ISO 29466 - Determination of thickness (full-size products)
ISO 29768:2022 provides a concise, practical framework for accurate linear measurement of insulation test specimens, supporting reliable test results and consistent quality assurance across the building insulation supply chain.
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