EN ISO 16535 Thermal Insulation Products for Building Applications - Determination of Long-Term Water Absorption by Immersion

The European standard "EN ISO 16535 Thermal insulation products for building applications - Determination of long-term water absorption by immersion," subsequently published by the International Organization for Standardization (ISO), describes the equipment and procedures used to determine the long-term water absorption of test samples. These procedures apply to thermal insulation products.

This standard includes two methods:

• Method 1: Partial immersion
• Method 2: Full immersion

Prolonged water absorption by partial immersion is intended to simulate water absorption caused by prolonged exposure to water. Prolonged water absorption by full immersion is not directly related to field conditions, but has been considered a relevant test condition for some products in some applications.

Principally,

• In the partial immersion method, long-term water uptake by partial immersion is determined by measuring the change in mass of a test specimen whose bottom portion is in contact with water for 28 days. Excess water adhering to the surface and not absorbed by the test specimen is removed by drainage in Method 1A or accounted for by deducting the initial water uptake in Method 1B.
• In Method 2, the total immersion method, long-term water absorption through total immersion is determined by measuring the change in mass of a test specimen completely submerged in water over a 28-day period. Excess water adhering to the surface and not absorbed by the test specimen is removed by draining in Method 2A or accounted for by deducting the initial water uptake in Method 2B. Method 2C utilizes Archimedes' principle to allow determination of water absorption without removing the specimen from the water tank.

The device used in these tests must have the following equipment:

• Balance capable of measuring the mass of a test sample with an accuracy of 0,1 g.
• A water tank containing a device that maintains the water level within plus or minus 2 mm and a device that holds the test specimen in the desired position. Examples of test devices are included in the figures. The device that holds the test specimen in position should not cover more than 15 percent of the cross-sectional area of ​​the test specimen exposed to water. The device should be designed to maintain the test specimen's original shape.
• Tap water adjusted to 23°C plus/minus 5°C. In case of disagreement, deionized water should be used. Different conditions and test conditions may apply in tropical countries. In such cases, the temperature should be 27°C plus/minus 5°C, and this must be stated in the test report.
• Drainage equipment. Examples are shown in the figures.

The thickness of the test specimens shall be equal to the thickness of the original product. Test specimens shall be square-cut prisms with sides of 200 mm plus/minus 1 mm. The number of test specimens shall be as specified in the relevant product standard or any other technical specification for thermal insulation products. In the absence of such a specification, a minimum of four test specimens shall be used. In the absence of a product standard or any other technical specification, the number of test specimens may be agreed upon between the parties. Test specimens shall be cut so as not to include the edges of the original product. Test specimens shall be prepared by methods that do not significantly alter the original structure of the product. Any external surfaces, finishes, and/or coatings shall be preserved. Specific preparation methods, where necessary, are specified in the relevant product standard or any other technical specification for thermal insulation products.

Test samples must be conditioned at 23°C (+/- 5°C) for at least 6 hours. In case of disagreement, they must be stored at 23°C (+/- 2°C) and 50% (+/- 5%) relative humidity for at least 6 hours, for the period specified in the relevant product standard. Different conditioning conditions may apply in tropical countries. In this case, the conditions must be 27°C (+/- 5°C) and 65% (+/- 5%) relative humidity for at least 6 hours and must be clearly stated in the test report.

Tests should be conducted at 23 degrees Celsius plus/minus 5 degrees Celsius. In cases of disagreement, they should be conducted at 23 degrees Celsius plus/minus 2 degrees Celsius. Different test conditions may apply in tropical countries. In this case, the conditions should be 27 degrees Celsius plus/minus 2 degrees Celsius and 50 percent relative humidity plus/minus 5 percent, and must be clearly stated in the test report.

The test method shall be as specified in the relevant product standard or other technical specification for thermal insulation products. In the absence of such a specification, the method may be agreed upon by the parties. Long-term water absorption is determined after 28 days of immersion. Upon request, readings may be taken at shorter time intervals, such as 7 and 14 days of immersion. The dimensions of the test specimens should be measured to the nearest 0,5 mm to ISO 29768 before testing. If any dimensional changes are noted after the immersion period, the dimensions of the test specimens should be re-measured.

The method of long-term water absorption by partial immersion is carried out as follows:

• Method 1A (drainage): The test sample is weighed to the nearest 0,1 g to determine the initial mass m0. The test is carried out with half of the samples facing up and the other half facing down. The test sample is placed in an empty water tank, and a sufficient load is applied to keep it partially submerged when water is added. Water is carefully added to the tank until the bottom of the test sample is 10 mm plus/minus 2 mm below the water surface. The water level should remain constant during the test. After 28 days, the test sample is removed and placed vertically in a 45-degree inclined strainer and drained for 10 minutes plus/minus 0,5 minutes. The test sample is weighed again to determine its mass.
• Method 1B (Deducting Initial Water Uptake): The test sample is weighed to the nearest 0,1 g to determine its initial mass. The test is performed with half of the samples facing up and the other half facing down. The test sample is placed in a water tank, partially submerged, with the bottom surface 10 mm plus/minus 2 mm below the water level. After 10 seconds, the sample is removed horizontally and placed within 5 seconds in a plastic tray of known mass. This tray is reweighed with the test sample to determine the mass of the test sample, including the initial water uptake.

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