BS EN ISO 4920:2012 pdf download.Textile fabrics – Determination of resistance to surface wetting (spray test).
BS EN ISO 4920 specifies a spray test method for determining the resistance of any fabric, which might or might not have been given a water-resistant or water-repellent finish, to surface wetting by water.
It is not intended for use in predicting the rain-penetration resistance of fabrics, since it does not measure penetration of water through the fabric.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (Including any amendments) applies.
ISO 139. Textiles — Standard atmospheres for conditioning and testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
spray rating measure of the resistance of the surface of a fabric to wetting
3.2 face fabric surface that is intended to be the outer visible side in an end product
4 Principle
A specified volume of distilled or fully deionized water is sprayed on a test specimen that has been mounted on a ring and placed at an angle of 45° so that the centre of the specimen is at a specified distance below the spray nozzle. The spray rating Is determined by comparing the appearance of the specimen with descriptive standards and photographs.
5 Apparatus and materials
5.1 Spray device1), consisting of a funnel of (150 ± 5) mm diameter held vertically, with a metal nozzle (52) connected to the end of the stem by rubber tubing of 10 mm bore (see Figure 1).
The distance from the top of the funnel to the bottom of the nozzle is (195 ± 10) mm.
5.2 Metal spray nozzle2), having a convex face with 19 holes of (0,86 ± 0,05) mm diameter (see Figure 2). The holes are distributed over the face of the nozzle. The duration of flow for the specified volume of (250±2) ml of water poured into the funnel shall be between 25 s and 30 s.
5.3 Specimen holder, consisting of two wood or metal rings, which fit into each other, one of inside diameter (155 ± 5) mm and another of outside diameter (155 ± 5) mm (for example an embroidery hoop), into which the specimen can be secured (see Figure 1).
The rings should, when in position for a test, rest on a suitable support so that it is inclined at an angle of 45 with the centre of the test area (150 ± 2) mm below the centre of the face of the spray nozzle.
5.4 Water, distilled or fully deionized, at (20 ±2) ec or (27 ± 2) °C, or other temperatures, as agreed between interested parties.
The temperatures used shall be stated in the test report 110 c)I
5.5 Graduated cylinder, 250 ml, class B.
6 Conditioning and testing atmospheres
Conditioning and testing shall be carried out according to ISO 139. If so agreed, conditioning and testing may be carried out in the ambient atmosphere.
7 Test specimens
Take at least three test specimens, each at least 180 mm square, from different places in the fabric so that they represent the material as fully as possible and can be secured by the specimen holder (5.3). Do not take test specimens from places with creases or fold marks.
8 Procedure
8.1 Condition the test specimens for at least 4 h in the atmosphere defined in Clause 6.
8.2 After conditioning, mount the test specimen securely on the specimen holder (5.3) with the face of the fabric uppermost on the hoop support. Place the holder on the support as specified in 5.3. Unless otherwise stated in the material specification, the specimen shall be orientated so that the warp, or length. direction is parallel to the flow of water down the specimen.
8.3 Pour (250 ± 2) ml of water (5.4) into the funnel (see 5.1) quickly, but steadily so that the spraying shall be continuous once it has commenced. The duration of flow shall be between 25 s and 30 s.BS EN ISO 4920 pdf free download.