GRAVITATIONAL LIQUID DOSING

LIQUID DOSING

One of the standard functions of modern weighing indicator is dosing, i.e. the control over filling of the packaging with a product. The indicator, by means of digital inputs/outputs, controls the opening of the valve and enables liquid to flow until the declared net weight value is obtained. In order to provide repeatability of indications, automatic correction is used - the average result of several processes is compared with the pre-set value and the calculated deviation is eliminated by closing the valve earlier/later in subsequent cycles. The problem arises when due to change of product quantity in the container the liquid pressure in the installation changes. In such a case, the calculated corrections do not work and the dosing process is inaccurate.

RADWAG engineers managed to solve this problem by introducing an innovative method of gravitational liquid dosing. The method consists in control of flow, not mass. 90% of the declared net weight of a product is pre-dosed. On the basis of the knowledge concerning the duration of the process, the instantaneous flow is calculated. Knowing its value, the indicator calculates the valve opening time needed to fill the container with a product until the pre-set value is obtained. As a result, the change in fluid pressure does not influence the accuracy of obtained results. This function is available for modern PUE HY10 indicators.