MATERIALS HANDLING: Gravimetric Stand Enhances Liquid Color Use

Riverdale Global will showcase its new Riverdale Gravimetric Stand for liquid color metering at NPE 2015.

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As part of a total system that aims to prevent the handling complications and workplace mess traditionally associated with liquid color, Riverdale Global, Perth Amboy, N.J. (riverdaleglobal), has developed the Riverdale Gravimetric Stand (RGS), which the company will showcase at NPE 2015. According to the company, gravimetric control has added a new dimension of accuracy and economy to its “no spill/zero waste” system for the supply, dosing, and replenishment of liquid color.

With Riverdale’s system, the color container is never opened, and drip-proof connections keep the color completely contained. The RGS enhances this system, whereby a liquid color drum is mounted on a self-calibrating loss-in-weight scale that continually reports the weight of the contents to the controller as a means of ensuring that the target let-down ratio is maintained. Flow is modulated through an air-regulated actuator that is connected to the liquid color pump, which is located inside the sealed drum, in accordance with the company’s proprietary “Pump in a Drum” design.

“Gravimetric metering holds color-delivery tolerance to within 0.1%, preventing over-coloring and making it possible to reduce costs while maintaining target color levels. Often, it is possible to reduce color usage by 5-10% in comparison with properly calibrated volumetric metering systems. The RGS controller adds to this accuracy,” says company president Paul Maguire. An operator in injection molding, for instance, simply enters into the controller the target shot weight and letdown ratio. The controller reportedly maintains accuracy automatically once it determines cumulative error over a number of cycles, eliminating the most costly cause of color waste—operator setting errors, he adds.