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Gravimetric Feeders
Gravimetric Feeding Principle
The bulk material or liquid is discharged from a hopper by weighing the material being fed and regulating the speed of the feeding device. The weighing system with control compensates for non-uniform material flow characteristics and variations in bulk density, and therefore provides for a high degree of feeding accuracy. Applications: Monitored feeding.Material control. Set point input manually or by host computer or in master/slave operation.
K-Tron generally employs following types of gravimetric feeding: Loss-in-weight feeding Weigh belt feeding Flow metering Loss-in-weight feeding principle: A feeding device with a hopper containing the material to be fed is placed upon a platform scale or suspension scale weighing system. The weight of the feeding device and hopper is electronically tared. The bulk material or liquid is discharged from the hopper by the feeding device and the resultant weight loss is determined by the weighing and control system.
This actual weight loss is compared to a desired weight loss per unit of time based upon a desired continuous feed rate set point. Any difference between the actual and desired weight loss per unit of time results in a correction to the speed of the feeding device. When the hopper content reaches a predetermined minimum weight level, the control by weight loss is briefly interrupted and the hopper is refilled. During the refill period, weight is increasing and the controller regulates the speed of the feeding device based upon the historical weight and speed information that was determined during the previous weight loss cycle.
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