Lentils – Chapter 18 | Official Grain Grading Guide

Determination of dockage

Definitions

Dockage is not assessed on lentil samples that meet the commercially clean specifications set out in the Lentil Export Shipments section. All samples must be analyzed to determine if they meet commercial cleanliness standards prior to dockage being assessed. The analysis of samples which are clearly not commercially clean may consist of a visual assessment. For example, if there is no doubt that a sample contains more than 0.2% of foreign material then dockage will be assessed using the procedures defined under Determination of Dockage. Where there is any doubt regarding whether the sample is commercially clean the sample must be analyzed.

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 three stages.

  1. Follow Determination of cleaning procedures using the No. 14 round-hole hand sieve.
  2. Follow Normal cleaning procedures, using the Carter dockage tester.
  3. Follow procedures for Cleaning for grade improvement. This cleaning can be done any time after the cleaning assessment has been completed.

Determination of cleaning procedures

Important:

Wear gloves and a mask to handle any samples that you suspect may contain hazardous substances.

  1. Using a Boener-type divider, divide from the uncleaned sample, a representative portion of approximately 250 g.
  2. Sieve the representative portion over the No. 14 round-hole hand sieve. When using hand sieves, move the sieve from left to right 20 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.
  3. Determine the portion remaining on top of the No. 14 round-hole sieve.

Note:

When results may be affected by excessive dockage material, reduce the material through sieving or handpicking without removing whole lentils.

Determination of clean lentils
If . . . The sample will be cleaned as . . .
10% or more remains on top of the No. 14 round-hole sieve Large
Less than 10% remains on top of the No. 14 round-hole sieve Small

Dockage not reported

Normal cleaning procedures

Important:

Dockage is not reported for samples grading:

  • Lentils, Sample Canada Account Fireburnt
  • Lentils, Sample Salvage
  • Lentils, Sample Condemned

Note:

Select the riddle that will achieve the maximum removal of large dockage material with the minimum removal or lodging of lentils.

1. Set up the Carter dockage tester as follows:

Setting Small Large
Feed control #5 #6
Air control #7 #7
Riddle No.1 or No.25 No.25 or No.6
Top sieve No. 9 round-hole No. 12 round-hole
Centre sieve blank tray blank tray
Bottom sieve none none
Sieve cleaner control Off 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. Turn off the dockage tester after sample passes through.

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

7. Remove the aspiration pan.

8.Determine dockage using the list under Composition of dockage.

Composition of dockage

  • Material other than whole lentils that remain on top of the riddle—whole sound lentils are returned to the sample
  • Material which passes through the selected round-hole sieve
  • Material removed by aspiration
  • Material removed by special cleaning for grade improvement procedures if the grade can be improved

Commercially clean (CC)

Primary samples are considered commercially clean when they contain 0.2% or less by weight of dockage material. No dockage is reported.

Cleaning for grade improvement

If the grade of a sample can be improved by additional cleaning to remove foreign material, 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 by hand using the appropriate hand sieve.

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.

2. Weigh the additional dockage and add it to the original dockage.

Cleaning for grade improvement
Size of lentil Equipment Effect on composition of dockage
Small No. 9x9 wire hand sieve, No. 10 round-hole hand sieve Material removed by the sieve is added to dockage. Not more than 5% of whole sound lentils may be removed for each single grade improvement.
Large No. 9x9 wire hand sieve Material removed by the sieve is added to dockage. Not more than 5% of whole sound lentils may be removed for each single grade improvement.