Bitumen test
The distance between the two lower sites is 25.4 mm. There are three holes in the middle site: the average for the thermometer 3 by 200 ° and two extreme 4 and 5 for brass rings with an internal diameter of 15.88 mm, a height of 6.35 mm. One ring for bitumen, another for steel balls with a diameter of 9.53 mm, weighing 3.45-3.55 g.
The molten bitumen is poured into the rings, let it freeze, align it with the edges of the ring with a knife and the ring is laid in the holes of the middle tripod site; Steel balls are placed on bitumen. A tripod with an inserted thermometer is immersed in a glass filled 50 mm above the level of rings with distilled water or glycerin with a temperature of 50 °. After 15 minutes. The device begins to heat at a speed of 5 ° per min. At the moment when Bituma deforming in the rings touches the lower tripod site, measure the temperature, which will be the temperature of softening of the tested bitumen. The Sofia online store offers its own production doors, details on the site
Glycerin is used when the estimated temperature of the softening of bitumen is above 80 °. The result of the test is the readings of the thermometer, between which the discrepancies should not be more than +0.5 °.
Each roll of aluminum foil is being checked. At the same time, they determine:
1) the thickness of the sheet (from 9 to 13 mk) with a micrometer with an accuracy of 0.5 mk and width (440-460 mm)-a metal ruler with an accuracy of 1.0 mm;
2) the weight of 1 m2 of the folga tape with an accuracy of 0.1 g (share of foil 2.7);
3) check the cleanliness and evenness of the surface, and also look through the ribbons, whether there are tears on them;
4) the diameter of the roll, the cleanliness of its ends, the tension of the foil, the presence of short ends (there should not be more than 10) and the correct dimensions of the sleeve, on which the roll is wound.