Monday, 19 November 2018


Unloading potatoes in a processing plant might be a challenge for any equipment producer. To learn how to best handle this first and important step in potato processing, Potato Business Digital spoke with specialists from Haith, Tong and Charlottetown Metal Products (CMP), who shared insights.

By Ioana Oancea

Nigel Haith, managing director Haith Group, explained that the first thing an equipment producer needs to know is how the potatoes will be delivered to the factory, by either truck, farm trailer or bins. The intake can be designed to handle all of these options. They also need to determine whether they need a sampling system before unloading, to make sure the quality is good, and what capacity the intake is required to handle, as well as an approximate percentage of soil they need to deal with. The equipment provider also needs to know if a small fraction of potatoes require grading out before storage, what access is required for inspection and maintenance and if they require inspection, manual or optical.

Edward Tong, managing director at Tong, says that storing potatoes in bulk or boxes will affect the equipment required at the end of the sorting line – box fillers vs. elevators, for example. Other parameters that need to be considered are the length of storage time, the storage temperature, ensuring gentle handling, soil removal and if the crop needs to be split graded.  

“For longer periods of storage, optimum storage conditions will be achieved by storing in boxes, meaning box filling equipment will be the preferred choice,” Tong says. The storage temperature is a key consideration for ensuring post-storage crop quality and that the store temperature requirements will differ for main crop versus processing crop. Regarding the handling, the equipment must be gentle to avoid bruising, he says. Removing the soil ensures the best conditions for storage, while facilitating good air movement and circulation through the crop during the storage period. If the crop needs to be graded – it will affect whether the unloading system needs to be equipped with grading equipment to split grade bakers, pre-packed etc prior to storage.

Trevor Spinney, CMP president, explains some of the possible methods of unloading potatoes from a truck. This can be done with an unloading system in the rear of the truck, by having a truck come into an angle that allows it to drop the potatoes out, or a when a truck unloads the potatoes trough the bottom.

Spinney says that it is important to determine from the beginning how the potatoes are going to be received and how they will be unloaded. In a modern French fry plant, usually the trucks will store 70,000 pounds of potatoes. The capacity and the speed of the unloading process are also important. “We need to determine what’s the size of the load what kind of production rate or off-load rate is required. Usually, potatoes are off-loaded as fast as possible. We’ve seen typical times at 20 minutes or 24 minutes to offload,” Spinney adds.

How to Avoid Damaging the Load

Damaging the charge is one of the challenges of the process.

“Damage is one of the main considerations when designing the system; we must keep all drops and transfers to a minimum. At any critical transfer point we would use padded, soft landing material,” Haith Group managing director recommends.

Tong’s managing director offers some advice for designing such a system.

Hopper equipment is designed with gentle handling in mind, for example with rubber ‘soft-landing’ hoppers. A cleaning unit that is effective yet gentle on crop is also important. “For example, the Tong EasyClean separator offers exceptional grip on leaf matter, soil and debris but does not grip the crop, ensuring the gentlest handling,” he mentions. Integrating an effective cleaner within the potato unloading system is a key factor in good storage conditions for crop, according to Tong’s specialist.

“In order to achieve the gentlest handling and very best control of crop cleaning in all conditions, on all crop types, the EasyClean is fitted with advanced touch screen controls to offer a simplified ‘touch of a button’ means of setting the machine to suit different crop cleaning requirements,” Tong adds. He explains that users can select crop conditions such as ‘Wet’ or ‘Dry’ and crop type from the display menu, setting the machine to automatically change the speed, position and direction of the cleaning rollers at the touch of a button. This makes adjusting the cleaner settings to suit different crop types and loads quick and easy.

In general, good practice when transferring crop from the trailer to the hopper can ensure a safe and gentle transfer of crop to ensure minimal bruising. Making sure the trailer is positioned correctly and closely to the hopper minimizes drop from trailer to hopper, according to Tong. Unloading crop into the hopper and securing a continuous steady speed of the hopper belt allows crop exiting the trailing to transfer in the hopper, meaning a very close transfer point and minimal damage, the expert says.

On the other hand, CMP’s Spinney points out that a very important aspect is to minimize the drop height from where you unload potatoes.
When the potatoes are transported, a series of conveyors are required, so the equipment producer has to pay attention to the transition from one conveyor to the next conveyor. “Often times, the actual drive from the roll head of the conveyor has a quite a large diameter, and you are incorporating various chutes from one conveyor to the next, so that you minimize the fall of the potatoes. Most uses are well under 12 inches or some more specified 16-18 inches drop as the maximum,” Spinney adds.  

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