Although BS 7611 outlines six size codes HK predominantly manufacture the more common size codes B and D.

Size Code B

Plan Dimensions:
Side 1830mm
End 1195mm

Maximum overall height 1070mm and maximum internal depth 945mm. It is possible to manufacture a box within these parameters which will hold a nominal 1.15 tonnes of potatoes.

Size Code D

Plan Dimensions:
Side 1525mm
End 1195mm

Maximum overall height 1220mm and maximum internal depth 1095mm. It is possible to manufacture a box within these parameters which will hold a nominal 1.1 tonnes of potatoes.

Connector Plates

BS7611 introduced higher strength requirements for potato boxes. In order to produce a box which conformed to Class 8 of the standard, yet have a clear internal finish with no trapping points during tipping, HK developed a design incorporating toothed metal plates. These are mechanically pressed into the boards of the side panel, literally binding the individual boards together. They sit between the side boards and the vertical battens and therefore do not come into contact with the crop also ensuring that replacing boards is practical. Boxes made with plates on the outside of the box prove very difficult to repair.

This method of construction considerably reduces racking movement in the box, and tests have proven this method to be stronger than the more conventional diagonal side bracing.

Diagonal Bracing

Although connector plates have eliminated the need for diagonal braces to provide resistance to racking forces, HK timbers use braces in the ends of boxes where less hindrance is caused when tipping. Connector plates can be supplied in box ends if required.

The incorporation of intermediate posts, which extend from the top of the box and through the deck to the floor, leads to an overall improvement in a box's strength compared to a box with vertical sides, and in particular an increase in the bowing resistance of the lower boards of the side panels, and a more even transfer of weight through the box during stacking. The central bearers also reduce the likelihood of damage to the post from fork lifts. However, there is more protrusion of the battens into the box, which may cause additional bruising on filling and emptying.

The choice between a gapped or close boarded box tends to be dictated by the end user's preference and the type of storage environment used. Both types can be manufactured to conform to BS7611 Class 8.

Any design of box can be altered to allow the addition of a pallet type deck to assist with tipping. By increasing the number of bearers, additional bottom battens are fitted across the length of the box, replacing the two battens which are otherwise fitted across the width of the box at each end.