This European Standard specifies the equipment and procedures for determining the long term water absorption of test specimens. It is applicable to thermal insulating products. This European Standard specifies two options: Method 1 - partial immersion, Method 2 - Total immersion. The long term water absorption by partial immersion is intended to simulate the water absorption caused by long term water exposure. The long term water absorption by total immersion is not directly related to the conditions on site, but has been recognized as a relevant condition of test for some products in some applications.