Page 115 - QRedition5.0 062021

Quality Requirements Edition 5.0 European Enamel Association

8.6 Testing of porcelain and vitreous enamel coatings 29. to 33. day daily water-replacement (5. week)
34. and 35. day no water-replacement

8.6.1 Determination of resistance to boiling water by long-term exposure 36. to 40. day daily water-replacement (6. week)
41. and 42 day no water-replacement

Purpose and scope 43. day: The test plates are, just like on the 22. day,
The enamelling of devices and receptacles, that have to face repetition of stress by means cleaned, dried and weighed.

of boiling or hot water, is tested for its constancy by a long-term exposure. Because of the
high expenditure of time that is necessary for the test according to EN ISO 28706-2/13, one Testing-device

has to - especially for hot water tanks - take some peculiarities into account. Apparatus according to EN ISO 28706-2/5

Method of testing Testing-time

The tests will be made according to EN ISO 28706-2 and the DIN 4753. Deviating from If no further arrangements have been made, a testing-time of 2 x 3 weeks is valid; the
the, under 7.3 mentioned boiling period, the testing time is set for 6 weeks, but during the second testing round is rated.

vapour phase a glass-plate (borosilicate glass 3.3 according to DIN 3585). The testing
solution is completely desalinated water of 1 mS/m conductance maximum. The water is to Testing-temperature

be renewed according to the following scheme: If no further arrangements have been made, a testing-temperature of ‘boiling’ is valid.

1. to 5.day daily water-replacement (1. week) Test plates
6. and 7.day no water-replacement The test plates should be made out of the same steel as the to be tested receptacle. Be-
8. to 12. day daily water-replacement (2. week) cause of the weighing accuracy, the plates should not be thicker than 2 mm. The enamel-
13. and 14.day no water-replacement ling should be of a thickness of at least 0.25 mm and its surface should be free of weak or
15. to 19. day daily water-replacement (3. week) defective spots.
20. and 21. day no water-replacement
22. day: The test plates are removed out of the The test plates can be produced either in the laboratory or in the enamel shop. In the last
device and are cleaned and weighed. case, the test plates should be hooked on a stainless steel hook and should be fired in the
After the weighing, the test plates interior of a receptacle of the production. Using this method, the sample enamelling gains
are put in the device again. The second the same thermal treatment experience as the receptacle-enamelling. Three test plates

testing round starts just like the first day. have to be tested. The average weight loss should not be higher than 8.5g/m .
2
23. to 26. day daily water-replacement (4. week)
27. and 28. day no water-replacement

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