Guide to Taking a Representative Sample

Chapter 5: Reducing your composite grain sample

5.1 Overview

Use the equipment and steps specified below to mix and reduce your composite sample into smaller samples. This will help ensure your samples are representative of the grain they were taken from and make the samples easier to handle and store. Keep in mind that you may need multiple samples for different purposes.

5.2 Boerner-type divider

A Boerner-type divider is a gravity-operated dividing apparatus that separates a grain sample into 2 smaller equal portions. The sample is placed in the upper hopper and released by opening the valve in the hopper throat. The sample flows downward and is evenly dispersed over a cone with evenly spaced separations. The divided sample is then directed into 2 grain streams, which empty into 2 collecting pans at the bottom.

The following are requirements of the Canadian Grain Commission’s Official Grain Grading Guide and the Canada Grain Regulations.

  • Official and unofficial samples used for dockage assessment and grading purposes shall be at least 1 kg.

Grading is done on representative samples that have been cleaned and then divided down using a Boerner-type divider.

A diagram of the components of a Boerner-type divider. Text version below.

Figure 38: Boerner-type divider

Figure 38 - Text version

A Boerner-type divider consists of the following components, beginning at the top of the divider: hopper, valve, cone, ducts, outer funnel, inner funnel, collecting pans

Procedure to divide a sample using a Boerner-type divider

  1. Clean the divider and collection pans.
  2. Close the valve at the bottom of the hopper and place a collecting pan under each of the 2 outlets.
  3. Pour the grain into the hopper.
  4. Open the valve quickly. The grain will fall by gravity over the cone and will be evenly distributed through the channels and spaces. The grain is divided into 2 halves, with each part being collected in one of the 2 collecting pans.
  5. To mix the grain, take the collecting pans and repeat steps 2 to 4 at least once for free-flowing grain and at least twice for chaffy grain.
  6. To reduce a sample, repeat steps 2 to 4. This will result in half of the sample in each collecting pan. Always use the collecting pan from the same side.

5.3 Sample dividing with pails

To divide a sample on a farm when a Boerner-type divider is not available, use this procedure to reduce your composite sample into a smaller sample that’s still representative of the grain in the bin. This will make the sample easier to handle and store. Keep in mind that you may need multiple samples for different purposes.

The Canadian Grain Commission’s Official Grain Grading Guide requires that unofficial samples used for dockage assessment and grading purposes shall be at least 1 kg.

To reduce a composite sample, you will need 3 pails: 1 pail labelled A, 1 pail labelled B and 1 pail labelled C.

mix the contents of pail A thoroughly by hand
1. Place the sample you’re dividing into pail A and mix thoroughly by hand.
place the two empty pails labelled B, side by side and touching on a level surface
2. Place the empty pails labelled B and C side by side and touching on a level surface.
pour the contents of pail A at the point where the pails touch, ensuring that half the stream flows into each pail labelled B
3. Pour the contents of pail A at the point where the pails touch, ensuring that half the stream flows into each pail B and pail C.
pour one pail of sample labelled B back into pail A
4. Pour the pail labelled B back into pail A.
pour the contents of the other pail labelled B back into the bin
5. Pour the contents of pail C back into the bin or truck in which it came from.
repeat this process with the remaining sample until you have the amount you need for your marketing purposes
6. Repeat this process with the remaining sample until you have the amount you need
place the final sample into the remaining pail labelled A
7. Place the final composite sample or samples in sealed containers and label each container to show the bin or truckload it represents.

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