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ISO 16925:2014 pdf free

ISO 16925:2014 pdf free.Paints and varnishes – Determination of the resistance of coatings to pressure water-jetting
The temperature shall be adjusted in accordance with Annex A. Necessary safety devices on the pressure side of the unit, as e.g. pressure relief valve and by-pass valve, shall exist. If the jetting is unsteady, a flow calming section may be installed in front of the nozzle. A pulsation of the water jet at the opening of the pump is inadmissible. In order to reach a reproducible result, the nozzle shall be solidly mechanically fixed and the test specimen shall be secured against slipping. For the adjustment of the volumetric flow rate, a nozzle with a jet angle of 25° and a volumetric flow rate of 6 l/min at 2 MPa (20 bar) is required (see Annex A).
Introduce both of the cuts or scribes vertically through the coating into the substrate using the cutting or scribing tool, as shown in Figure 2. The depth of the cut or scribe into the substrate should be as minimal as possible. The length of the first cut or scribe shall be at least 100 mm, if the geometry of the part allows that. At an angle, introduce a second cut or scribe with a minimum length of 20 mm. The cuts or scribes shall be introduced straight-line at an angle of approximately 30°. An automatic cutting or scribing device may be used. Residues of the coating shall be removed from the cut or scribe.
NOTE The depth of the cut or scribe into the substrate influences the result.The cutting or scribing tools should be checked regularly and replaced if necessary.The repeatability limit r is the value below which the absolute difference between two test results (each the mean of valid duplicates) can be expected to lie when this method is used under repeatability conditions. In this case, the test results were obtained on identical material by one operator in one laboratory within a short interval of time using the standardized test method. In this International Standard, the repeatability limit r is one characteristic value with a preset probability of 95 %.ISO 16925 pdf download.

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