AATCC 35-2018 Water Resistance: Rain Test.
7.1 The test specimen (see 11.5), backed by a 15.2 × 15.2 cm standard pa- per blotter weighed to the nearest 0.1 g is clamped in the specimen holder and the assembly is mounted in a vertical rigid support frame. The specimen assembly is positioned into the central portion of the spray at a distance of 30.5 cm from the face of the spray nozzle (see 11.6). A hor- izontal water spray at 27 ± 1°C (81 ± 2°F) (see 11.2) is directed against the specimen and is allowed to continue for a period of 5 min. At the end of the spray period the blotter is carefully removed and quickly reweighed to the nearest 0.1 g.
8.1 Water penetration as indicated by the increase in mass of the blotting paper during the 5 min test period is calculated, and the average for the three test specimens is reported. Individual determinations or average values of over 5.0 g may be simply reported to 5 + g or > 5 g. 8.2 In order to obtain a complete overall picture of the penetration resistance of a fabric or fabric combination the average penetration with different pressure heads on the nozzle should be obtained. The pressure head should be varied by 300 mm increments in order to determine (a) the maximum head at which no penetra- tion occurs, (b) the change in penetration with increasing head and (c) the mini- mum head required to cause “break- down” or the penetration of more than 5 g of water. At each pressure head a mini- mum of three specimens should be tested in order to obtain the average penetration for that head.
9.1 Report the individual determina- tions. For values of over 5.0 g simply re- port as 5 + g or > 5 g.
10. Precision and Bias
10.1 Precision. Precision for this test method has not been established. Until a precision statement is generated for this test method, use standard statistical tech- niques in making any comparisons of test results for either within-laboratory or between-laboratory averages.
10.2 Bias. The bias derived by this procedure can be defined only in terms of a test method. There is no independent, ref- eree test method by which bias may be determined. This test method has no known bias.
11.1 The intensities are produced and con- trolled by means of a column of water which may be adjusted to 0.6, 0.9, 1.2, 1.5, 1.8, 2.1 and 2.4 m above the nozzle. This is done by means of a glass pressure column to which a nozzle is connected. The adjustment is made by a simple setting of a valve at the lower end of the drain or overflow pipe which extends up through the center of the glass column. A filtering device between the pressure gauge and the glass column may be used to prevent clog- ging of the nozzle openings. It may be eliminated in localities where the water supply is relatively free from iron rust or other suspended matter. A pressure gauge on the supply line also is an accessory which usually can be eliminated in the interest of economy.
11.2 The temperature of the supply water may be measured by means of a thermometer, but recent work has shown that it is more con- veniently and accurately measured with a ther- mometer suspended in the glass pressure column or immersed in a beaker placed to catch water from the overflow.
11.3 The AATCC Rain Tester is available from AATCC, P.O. Box 12215, Research Trian- gle Park NC 27709; tel: +1.919.549.8141; fax: +1.919.549.8933; e-mail: firstname.lastname@example.org; web site: www.aatcc.org. Information relative to the principle of the instrument may be ob- tained by reference to the original article by Slowinske, G.A. and Pope, A.G., American Dye- stuff Reporter, Vol. 36, 1947, p108.
11.4 Blotters suitable for this test can be obtained from AATCC, P.O. Box 12215, Research Triangle Park NC 27709; tel: +1. 919.549.8141; fax: +1.919.549.8933; e-mail: email@example.com; web site: www.aatcc.org.
11.5 The test specimen may comprise (a) a single layer of the test fabric, (b) two layers of the test fabric, or (c) a combination of two dif- ferent fabrics such as the outer fabric of a rain- coat and the lining fabric.AATCC 35 pdf download.