Measurements show that the inertial material sifted through the roar corresponds to the norm, but the quality of the finished canvas leaves much to be desired. The reason is in the wrong form of the holes of sifting equipment.
Norms and attitude towards them
In world practice, it is generally accepted that the roar inertial for sifting bulk materials works satisfactorily if the amount of impurities of other fractions in the material obtained is 10% or less. In practice, they often allow an error up to 15-17%, due to unwillingness to bear unnecessary costs for frequent repair of worn equipment. This is allowed by construction standards, but the problem is that the actually used equipment has completely different characteristics.
In the manufacture at the factory, all installations, including a strip feeder and crushers, are certified and guaranteed to have the parameters indicated in the documents. But at the place of work, they are often subjected to artisanal modernization in order to increase the efficiency. At the same time, it does not undergo a check in the road laboratory, which is why for the increased speed of work you have to pay the error of cleanliness of sifting about 30-40%. This could be eliminated by calibration if not for one nuance.
Road laboratories are not to blame
The fact is that GOST, according to which an inertial roar is evaluated, is developed under an outdated sieve with a circular cell cell. Whereas the vast majority of manufacturers have long been used by Sita with square cells. As a result, practical measurements may correspond to regulatory indicators, but in fact, the signs of the wems will be 5-7% higher than the poor quality of the coating is explained even if all standards and technological requirements are followed during operation.
The measurements are based on the fact that the diameter of the round cell and the length of the side of the square are identical, which means that only pieces of breed of no more specific size can pass through them. However, the length of the diagonal of the square is greater than the diameter of the circle and when it enters the sieve at a certain angle, several larger fractions pass through it through it. As a result, a breed of far from the cleanliness on which the technological process of manufacturing the roadway is designed to the strip feeder.
