An order of grain to be loaded aboard a ship, referred to as a "lot", is divided into smaller units called "sublots" for inspection purposes. A sublot which does not pass inspection, referred to as a "material portion," is not allowed to be loaded onto the ship. Grain is Inspected by sublots rather than waiting for the entire lot to be loaded so the lot will be of uniform quality. A lot is often divided among several customers at its destination, so it is important for no customer to be stuck with a pocket of bad grain. Also, a pocket of bad grain could spoil during the voyage and contaminate the rest of the shipment.
Every elevator has a different layout. The following diagram shows the essential equipment arranged in a typical way. Blue represents grain coming from storage, being weighed, sampled, and held in a shipping bin while it is being graded. Yellow represents grain which has passed inspection and is being loaded onto a ship. This diagram is also an image map. Click on a piece of equipment in the diagram for an explanation of that piece of equipment.
The scales in a grain elevator are a critical piece of equipment, and are tested carefully by FGIS. Follow this link for a demonstration of scale operation and testing.
Samples of grain which are conveyed to the lab for official inspection are extracted from the grain stream by a Diverter-Type (D/T) Sampler. Follow this link for a Virtual Reality Model of a D/T Sampler.
Large elevators typically use a good deal of automation. Follow this link for a brief description of electronic controls and limit switches.
Follow this link for a Virtual Reality Model of a Shipping Bin.