Riverdale gravimetric metering system for liquid colors

Automatic refill system for liquid colors refills drums on-line

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  • “Pump in a Drum” design
  • Eliminating downtime for switching drums
  • Gravimetric control holds color-delivery tolerance within 0.1%

Riverdale Global has developed a material handling system that automatically refills one or more liquid color drums during the molding or extrusion process, eliminating downtime for switching drums and reducing the occurrence of transitional or off-specification product with little or no color.

Auto-refill system refills drums on-line

The company supplies liquid color in patented pump-equipped drums that remain sealed while color is metered to the processing machines. The RGInfinity auto-refill system eliminates need to replace these drums when empty by refilling them from a large central container, or “tote.” One central container can serve one machine or, if desired, be configured to refill multiple machines running the same color.

Liquid color kept completely sealed off from workplace

Sealed connections throughout the system, from tote to delivery tubes to drums to metering tubes, keep liquid color completely sealed off from the workplace. Each drum is mounted on a Riverdale Gravimetric Stand (RGS), which monitors the weight of color in the drum and signals a pump valve on the tote when the drum is nearly empty and again when it is full. This prevents uncolored product. When the central container needs to be replaced with a full one, the sealed connectors make possible a quick changeover.

The company can provide containers in various shapes and sizes. A typical example is a 200-gallon rotomolded plastic vessel within a steel supporting framework, but it is possible to use a standard-size drum for refilling the on-line drum, replacing the empty “refill” drum with a full one while color metering continues uninterrupted.

RG Infinity System for liquid colors

RG Infinity System for liquid colors (source: Riverdale)

System eliminates time and labor required to monitor color levels

“Besides preventing downtime, the RGInfinity auto-refill system eliminates the time and labor required for operators to monitor color levels, transport and prepare replacement drums, and wait until on-line drums are finally ready for replacement,” said Kevin Cabana, vice president of process technologies. “Also prevented is the human error that creeps in during these procedures, particularly when there are multiple drums metering color to multiple processing machines.”

“Pump in a Drum” design

The RGInfinity auto-refill system is an extension of Riverdale Global’s Sealed Color technology, which eliminates the complications of handling liquid color, such as spillage, leakage, cleanup, pump maintenance, unused color, environmental concerns, and disposal costs. Central to the technology is the proprietary “Pump in a Drum” design, which enables the drum to remain sealed during delivery from Riverdale Global, metering into the process, and replenishment through return of the drum to Riverdale Global.

Gravimetric control holds color-delivery tolerance within 0.1%

In the Riverdale Gravimetric Stand, used as part of the auto-refill system, a liquid color drum is mounted on a self-calibrating loss-in-weight scale that continually reports the weight of the contents to the RGS 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 pump inside the sealed drum. The gravimetric control holds color-delivery tolerance to within 0.1%, preventing over-coloring and making it possible to reduce costs while maintaining target color levels.

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