Detailed background information about grain inspectioncan be found in the Grain Inspection Handbook, downloadable in Adobe Acrobat format from the U.S. Department of Agriculture. The price of grain varies with its grade or quality so there is great economic incentive to have the representative samples be as accurate as possible. There are many different grades of acceptable grain and these are mixed by the grain elevator operator to produce a more consistent final blend. Frequent samples are also necessary to identify containers transporting unacceptable grain or deceptively loaded grain. Strict guidelines define exactly how samples are taken and how much bad grain in a container is enough to condemn the entire container.
Grain is sampled often and according to well defined rules.
The grain elevator operator stays informed about the quality of grain brought to the elevator by truck or rail and checks the grain again during the blending process using automated samplers. Probe samplers are allowed for use on trucks and railroad cars. The depth of the carrier or container dictates the length of probe used to draw the sample. Probes consist of two tubes, one inside the other. The inner tube is divided into compartments.