Determination of commercially clean
Duration: 2 minutes, 45 seconds
The Canada Grain Act states Canadian grain must be commercially clean when it is shipped to export markets.
In order to assess if Canadian wheat is commercially clean, Canadian Grain Commission inspectors use a precise process called Determination of Commercially Clean. The Canadian Grain Commission has strict tolerances for the presence of different components: small seeds, attrition, roughage, large seeds, wild oats and broken grain.
Two hand sieves are used. One sieve has triangular openings while the other has round openings. These sieves allow different components to pass through.
The process requires a representative sample. Wheat is sampled continuously throughout the loading of a vessel and is analyzed incrementally.
The sample is sieved in smaller portions. One complete motion is from the centre to one side, back to the centre, to the other side and back to the centre. This is repeated 30 times for each portion until the entire sample has been sieved.
Components are now segregated. The top sieve contains the sample along with large seeds, wild oats and roughage. The second sieve contains large seeds, whole grain and broken grain. The pan contains small seeds, broken grain and attrition.
The contents of the top sieve are set aside for now. This will be used later in the process.
The contents of the second sieve are separated. Components are placed in containers and set aside for use later in the process. Large seeds are recombined with the contents of the top sieve.
The contents of the pan are separated. Components are placed in containers and set aside for use later in the process.
A Boerner divider creates a representative working portion for further assessment. The contents of the top sieve are used for this part of the process. Wheat runs through the divider and splits into equal portions. The bowl contains the representative working portion. The remaining contents of the top sieve are set aside for use later in the process.
Large seeds, wild oats and roughage are separated from the representative working portion. The remaining wheat is recombined with the contents of the top sieve. This is no longer needed for this process. It is set aside to be used for further evaluation of the sample.
The process for the Determination of Commercially Clean is almost complete.
The components are weighed individually. The percentage of each component is calculated and recorded.
If the sample meets Canada’s strict tolerances it is determined commercially clean.