Overview
ISO 20393:2007 is an international standard specifying the equipment and procedures for determining the long-term water absorption of thermal-insulating materials by diffusion. This test method simulates the exposure of insulation products to conditions of nearly 100% relative humidity on both sides along with a water vapor pressure gradient-common in applications such as inverted roofs or unprotected ground insulation. The standard is crucial in assessing the durability and performance of thermal insulation under prolonged moisture exposure, which can significantly affect thermal efficiency and material longevity.
Key Topics
-
Scope and Applicability
The standard applies specifically to thermal insulation products and is not suitable for all insulation types. Product standards should indicate whether ISO 20393:2007 testing is relevant for a particular material.
-
Test Principle
The principle involves measuring the mass increase of test specimens subjected over 28 days to a controlled water vapor pressure difference and temperature gradient (50°C on the water side and approximately 1°C on the cooling plate side).
-
Specimen Requirements
Specimens must be squares with a side length of 500 mm (or smaller if limited by product size), cut without joints, and retain all coatings or facings. Conditioning involves specific relative humidity and temperature settings to stabilize the material before testing.
-
Equipment and Setup
Essential test apparatus includes a corrosion-resistant container, a temperature-controlled heating device, an insulated cooling plate, and a precision balance (accuracy within 0.1 g). The setup mimics real-world moisture diffusion conditions for long-term evaluation.
-
Testing Procedure
The specimen is weighed before and after the 28-day exposure. It is flipped every 7 days to ensure uniform moisture exposure. Post-test, the specimen is wiped dry and reweighed to calculate water absorption.
-
Calculation of Results
Water absorption is expressed in kilograms per square meter or as a volume percentage. The standard provides formulas to calculate these values based on mass gain, specimen area, thickness, and water density.
-
Reporting Requirements
Test reports must reference ISO 20393:2007, provide detailed product identification, test procedure information, specimen dimensions, and all measured results with averages. Deviations and conditions affecting results should also be documented.
Applications
ISO 20393:2007 is essential in evaluating thermal-insulating products used in environments exposed to high humidity and water vapor gradients. Its practical applications include:
-
Roofing Systems
Testing inverted roofs where insulation is exposed to moisture from both above and below.
-
Ground Insulation
Assessing unprotected insulation materials placed directly on or in the ground, which are prone to long-term moisture uptake.
-
Building Materials Quality Control
Ensuring consistent product performance by verifying resistance against water absorption, which impacts thermal insulation effectiveness and structural integrity.
-
Product Development and Certification
Assisting manufacturers in developing more durable insulation products and providing data necessary for product certification and compliance with environmental conditions.
Related Standards
-
ISO 472: Plastics - Vocabulary
Provides terminology used within ISO 20393 relating to plastics and cellular plastics.
-
ISO 1923: Cellular Plastics and Rubbers - Determination of Linear Dimensions
Defines methods for measuring specimen dimensions for preparation in the water absorption test.
ISO 20393:2007 is part of a broad framework of standards designed to ensure the quality and longevity of thermal insulation materials critical for energy-efficient construction and environmental safety. Utilizing this standard improves understanding of insulation behavior under moisture exposure, facilitating better product design and building performance.
Open preview (PDF)Thermal-insulating materials — Determination of long-term water absorption by diffusion
