Accuracy Level

First level accuracy is the national standard kept in environmentally controlled conditions by your equivalent of the National Standards Authority.

Second level accuracy are the weights used to calibrate your scale. These will have been tested against the national standard and will have a dated certificate to prove it. Usually these weights need retesting every one or two years.

The third level accuracy is your scale. Minor discrepancies are introduced each time one weight is calibrated against another weight or in your case a set of scales. There are many other causes of discrepancy to your material flow reading, and provided the scale is calibrated regularly, typically once per year, and zeroed regularly, typically once per month, you will display a material flow that is within most industrial tolerances. Some industries such as pharmaceuticals are special cases and require extreme tolerances but they don't weigh materials on belt conveyors.