Mixed grain - Chapter 9 | Official Grain Grading Guide

Determination of dockage

Important:

When a sample is to be graded as mixed grain, return dockage to the cleaned sample, and begin Normal cleaning procedures described in this section.

Definitions

Dockage is assessed and recorded to the nearest 0.1%.

Dockage is defined under the Canada Grain Act as “any material intermixed with a parcel of grain, other than kernels of grain of a standard of quality fixed by or under this Act for a grade of that grain, that must and can be separated from the parcel of grain before that grade can be assigned to the grain.” Dockage is removed by following the cleaning procedures described in this section of the guide.

The sample as it arrives is referred to as the uncleaned or dirty sample. Its weight is the gross weight of the sample. Dockage is assessed on the gross weight of the sample.

Dockage is assessed in two stages.

  1. Follow Normal cleaning procedures, using the Carter dockage tester.
  2. Follow procedures for Cleaning for grade improvement. This cleaning can be done at any time after the cleaning assessment has been completed.

Dockage not reported

Important:

Dockage is not reported for samples grading.

  • Mixed Grain, Sample CW/CE Account Fireburnt
  • Mixed Grain, Sample Salvage
  • Mixed Grain, Sample Condemned

Normal cleaning procedures

1. Set up the Carter dockage tester as follows:
Feed control 6
Air control Minimum 4
Riddle No. 6
Top sieve No. 6 buckwheat
Centre sieve No. 5 buckwheat
Bottom sieve No. 4.5 round-hole
Sieve cleaner control Off

2. Using a Boerner-type divider, divide the uncleaned sample to obtain a representative portion.

  • Official samples shall be at least 1 kg.
  • Unofficial samples shall be at least 1 kg.

3. Turn on the Carter dockage tester

4. Pour the sample into the hopper.

5. After the sample has passed through the machine, turn on the sieve cleaner control for two to three seconds to remove kernels lodged in the sieve.

6. Turn off the dockage tester.

7. Lightly snap the retainer rod of the aspiration pan to loosen material gathered on the air screen.

8. Remove the aspiration pan.

9. Determine dockage, using the list under Composition of dockage.

Composition of dockage

Dockage includes

  • Material handpicked or removed over the No. 6 riddle
  • Lightweight material removed by aspiration
  • Material that passes through the No. 4.5 round-hole sieve
  • Material such as large seeds removed by the No. 5 buckwheat sieve in excess of the grade tolerence for total foreign material
  • A maximum of 10% of soft earth pellets handpicked from the clean sample
  • Material removed by Cleaning for grade improvement

Cleaning for grade improvement

If the grade of a sample can be improved by additional cleaning, perform the cleaning and add the additional material to dockage. Cleaning for grade improvement can be done at any time after the cleaning assessment has been completed.

  1. After the cleaning assessment has been completed, sieve the sample, using the No. 6 buckwheat hand sieve.
  2. Weigh the additional dockage and add it to the original dockage.

Important:

When you use a hand sieve, move the sieve from left to right 30 times, using a sifting motion. One time is one complete motion from the centre, to one side, to the other side, and back to the centre. The total distance from left to right is 20 cm, or about eight inches.

Cleaning for grade improvement - Mixed grain
Material to be removed Equipment Effect on composition of dockage
Large seeds No. 6 buckwheat hand sieve Large seeds are seeds that pass through the No.6 buckwheat sieve. Add them to dockage.
Stones No. 6 buckwheat hand sieve Add all stones that pass through the No.6 buckwheat sieve to dockage.

Optional analysis

Where a shipper requests special cleaning of a carlot of grain at a terminal elevator, and the elevator manager agrees, dockage material will be analyzed for the presence of grain. The percentage and grade of any grain contained in the dockage will be reported.

Procedures

  1. Analyze the official sample.
  2. Record the following on inspection records:
    • The percentage by gross weight to the nearest 0.1% and the grade of mixed grain.
    • The percentage by gross weight to the nearest 0.1% and the grade of grain separable from dockage.
    • The percentage of dockage.
Example:

95.0% Mixed Grain CW Wheat

4.0% Domestic Mustard Seed, No. 1 CAN Oriental

1.0% dockage