Hydrostatic Head, Spray Rating and Shower Room

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Chad Caldwell
5 years ago
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1 Hydrostatic Head, Spray Rating and Shower Room Introduction: The labs conducted were Hydrostatic Head, and Spray Rating and Shower Room. The hydrostatic head test looks at a fabric s resistance to water penetration; water moving through the fabric from one side to the other. A test is considered failed if 3 drops of water make it through to the opposite surface before a pressure of 10 m of H 2 O is reached, this includes if the fabric tears before this pressure. The spray rating test looks at a fabric s surface wetting. This gives more information to a fabric s surface tension; how the water reacts while sitting on the surface of one side. After the fabric is sprayed, it is compared to a set of ISO standards to find its rating. In contrast to the first two tests, the shower room test evaluates an entire garment s performance in rain. However, in similarity to the previous two tests, it also looks at the garment s resistance to water penetration and surface wetting. Methodology: For hydrostatic head and the spray rating testing, follow the method outlined in BS , method 29C. The water was applied from below the test specimen. The hydrostatic head tested three different types of fabrics, one that is coated(blue), one that is laminated(green), and one that has nothing done to it(white). Each sample of fabric was tested before it was stretched, and after it was stretched. The water was applied to the side which, if the fabric was used in a garment, would be exposed to outside environment (rain). For spray rating testing, follow the method outlined in BS , method 29D. The spray rating test was completed on 4 different jackets, but only on sections displaying one type of fabric, no seems. For rain room testing, follow the method outlined in BS EN and the Template for Test Report of Rainroom Testing handout 3. Only one jacket tested, and a simple woven jumper with non-wicking material placed underneath. Once the test was completed the jacket was checked for ingress and the jumper underneath examined for wetting out.

2 Results: For Hydrostatic head. Table 1.1: Pressure at point of failure Pressure (m of H 2 0) Pre-stretched Trial 1 Trial 2 Trial 3 White fabric Green fabric Blue fabric >10(pass) 6 >10(pass) Stretched White fabric Green fabric Blue fabric 9.5(1 drop, 1 rip) >10 (2 drops) -

3 For Spray rating. From BS : Table 1.1: Spray rating test results Jacket type Trial 1 Trail 2 Leisure 1 - Fireman 1 1 Postman Other

4 For Shower room. The blue spots are areas of ingress wetting. The jumper was checked for wetting out but none was found.

5 Discussion: The hydrostatic head test gave a good idea of how waterproof a sample fabric is, however it doesn t seem entirely realistic. It is difficult to think of an example of when a small section of fabric would be subjected to such a high intensity of water exposure. The blue fabric was the most water resistant out of the three fabrics tested, with passes at pressures greater than 10m of H 2 O both pre-stretched and stretched. It was a coated fabric, and the one time it did fail, there is a possibility that there was a coating discrepancy in that particular area. Another interesting observation was with the green laminated fabric, the spaces between the glue drops would soak through with water before the drops actually pushed through the fabric. Stretching the fabric didn t seem to have much of an effect on the water permeability of the fabrics; at least no correlation was apparent as the stretched test results were all very similar to the pre-stretched results. The spray rating test was good at demonstrating the different surface energies of fabrics. The drops seemed very large; larger than any rain drops, but if even the large drops manage to roll of the sample than smaller rain drops should perform the same. The other jacket was extremely hydrophobic with ISO rating between 2 and 3. It water was able to form a close to sphere shape and roll of the fabric. The leisure and fireman jackets were the most hydrophilic and had ISO ratings of 1. The water droplets flattened on the fabric was not able to run off. The shower room gave a good representation of a rain storm (15mm/hr) 4. The water spraying set-up created accurate sized droplets, whereas other testing methods create larger droplets more representative of the water pooling at the edge of something and spilling over. It would have been beneficial to have a mannequin with moving limbs, but the rotating base was a good alternative. The jumper underneath the jacket wasn t long enough to cover the mannequin as much as the jacket. Some of the ingress wetting on the bottom edge of the jacket was very soaked through. There is a possibility that it might have been wet enough to wet out in this area had the jumper been there to show evidence of it. Most other seemed areas seemed to be fine, but perhaps this area was in an awkward location and so wasn t able to be tape-sealed properly or at all.

6 1. BS :1990, Testing coated fabrics: Part 26: Methods 29A, 29B, 29C and 29D. Methods for determination of resistance to water penetration and surface wetting, London: BSI 2. BS EN 14360, Protective clothing against rain Test method for readymade garments Impact from above with high energy droplets, London: BSI 3. Performance Textiles and Clothing Group, Template for Test Report of Rainroom Testing, School of Design, University of Leeds 4. As mentioned as part of the set up discussion.

BS EN 14605: 2005 Type 3 or 4 Protective Clothing

BS EN 14605: 2005 Type 3 or 4 Protective Clothing Protective Clothing against liquid chemicals Performance requirements for clothing with liquid-tight (Type 3) or spray tight (Type 4) connections, including