Challenge Exeter Engineering was asked to design a sweet potato packing line that would gently unload, wash, grade, and package the product at an incoming weight of 70,000 lbs. per hour. The customer’s major considerations were increased packing flexibility and reducing labor requirements and associated costs.


Exeter Engineering worked closely with the client to understand their needs, budget, and the space where the line was to go. The resulting design starts with the sweet potatoes delivered in packing bins 1,000 lbs. each, stacked three bins high. An Exeter Engineering XTR 500 Portal Dumper unstacks the full bins one at a time, submerging the entire bin in the water of our Series 4000 Wet Reception Tank. The Series 4000’s innovative design features an auger at the bottom of the tank that drives out the accumulated soil on a pre-timed basis, allowing for most soil to be removed without removing the water.

After submerging, the XTR500 empties the bin onto a conveyor, which passes them under a fresh water finish rinse. From there, the product goes through a telescoping infeed conveyor to our Series 1200 Horizontal Brush Washer. As product skin set and dirt condition change, the infeed conveyor telescopes atop the Series 1200 Brush Washer, allowing for more or less time for the product to be scrubbed.

From the Series 1200, the sweet potatoes pass through a Lift-Roll Diameter Sizer that evenly distributes the product, by diameter, across the infeed of one of our 12 lane AccuVision sorters. For this line, pre-sizing by diameter improves product singulation on the transport lanes. The AccuVision separates the product via any combination of sizer, shape, calibrated weight, color and major external defects. The AccuVision separates the sweet potatoes over 16 different drop points for various packaging options. Ten of the sixteen drops are equipped with Exeter Engineering’s AccuFill automatic carton fillers, which automatically fill 6kg, 12kg, 40 lb. and RPC containers as required by the customer’s needs. Three other drops feed electronic bagging machinery selected by the client, while the remaining three drops feed re-binning stations, mostly for process and second grade product.


The new packing line doubled the customer’s volume and reduced their labor costs by 25%. In addition, the total pounds of product packed per hour/per person have increased by approximately 300%. The customer also reports that product utilization (amount of dollar value per bin) also increased as a result of increased packing flexibility and ability to meet different market opportunities.