Sampling Systems Handbook and Approval Guide

4. Manual sampling

4.1 Manual stream sampling

Samples taken from the grain stream must be drawn at regularly timed intervals from the beginning to the end of the transfer. Equipment that can be used for manual sampling under these conditions is described as follows:

Hand scoop

The hand scoop is a sampling device consisting of a rigid material scoop attached to a 50-100 centimetre handle which is stiff and durable. The sample collector capacity must be a minimum of 50 grams and not more than 200 grams.

Diagram of 3 types of hand scoops.
The line drawing shows 3 different hand scoops

When manual stream sampling with a hand scoop off the top of a belt, insert the sampling tool into the stream at an alternate point across the stream (left, middle, right) for each sampling action. The scoop should be placed into the flow of product “upstream” and matching the belt speed, moved “downstream”, as the scoop is turned to fill with grain. Moving the scoop with the flow allows sampling of the appropriate location on the belt without splashing product or overflowing the scoop.

When manual stream sampling free-flowing product, the scoop should be placed in to the flow of product upside down, then rotated 180 degrees to fill, and then pulled out of the product flow.

4.11 Determining sampling frequency when stream sampling

Caution: Sampling must be done in an area where the entire grain stream is accessible. All safety precautions must be adhered to when attempting to sample from a grain stream or near a moving conveyor.

Stream sampling bulk grain into containers

The sampling frequency is determined by the how much time is needed to load the grain and the lot size. The Canadian Grain Commission requires a minimum of 5 primary samples per 20 tonne container, collected systematically at evenly spaced timed intervals (at least one primary sample every 4 metric tonnes). If a larger composite sample is required, reduce the interval between primary sample collections throughout the entire loading process.

Example to determine sampling frequency:

The grain lot is 2 containers of 20 tonnes each and will be loaded in approximately 30 minutes.
40 tonnes total weight ÷ 4 (1 sample per 4mt) = 10 samples minimum are required.
30 minutes to load the lot ÷ 10 required samples = 3 minutes.

A sample will be taken at timed intervals every 3 minutes throughout the entire loading of the 40 tonne lot.

The hand scoop that is being used in this example has a capacity of 200 grams.

10 scoop samples x 200 grams per scoop = 2000 gram sample will be collected for this lot.

Note: if a larger composite sample is required, the solution is to shorten the interval between samples, and not increasing the size of the scoop.

Stream sampling large bulk lots

Procedure:

  1. The sampling frequency must be at least one primary sample selection per minute taken systematically throughout the entire transfer.
  2. On commencement, insert the hand scoop into the grain stream at alternating points across the stream (left, middle, right). The scoop should be placed into the grain flow “upstream” and overturned. While moving “downstream”, the scoop is turned to fill grain. Moving the scoop with the grain flow allows sampling of the appropriate location in the grain stream without splashing grain or overflowing the scoop.
  3. Examine the primary samples for uniformity while sampling.
  4. Combine the primary samples in a sample container to form a composite sample.
  5. Reduce the composite sample to the appropriate size using a Boerner-type divider.

4.2 Manual sampling static lots

Grain may be sampled when stored in bags or totes. Bags are considered to be grain sacks generally weighing 100 kilograms or less, totes are considered to be grain stored in sacks generally weighing 100 kilograms or more. The equipment used to sample grain stored in totes or bags is the double sleeved trier, or nobbe trier.

A photograph of grain storage totes.
Grain storage totes

A photograph of stacked grain storage bags.
Grain storage bags

Equipment - double sleeve trier

The double sleeve trier consists of a hollow tube with a solid pointed end and a close fitting inner tube such that the product cannot slip between the two sleeves.  The inner tube may be with or without partitions (fixed or removable plugs) between the slots. Partitioned double sleeve triers may be used horizontally or vertically. Double sleeved triers without partitions may only be used vertically when sampling sacked grain weighing greater than 100 kilograms.  Vertical sampling of sacked grain 100 kilograms or less must be undertaken with the partitions in place.

A photograph of 3 different sizes of double sleeve triers.
Double sleeve trier (various sizes)

Multiple openings (slots/holes) are cut into both the inner and outer tubes so that turning the inner tube aligns the openings of the inner and outer tubes. There is a greater risk of contamination with this type of trier. Care must be taken to ensure that all the openings in both the inner and outer tubes are clean and no small seeds or particles are lodged between the two tubes. When closing the openings there is a risk of damaging the product trapped between the edges of the slots but this damage can be reduced by closing the openings slowly to the point where resistance is felt.

The contents of the entire tube represent one primary sample. When sampling horizontally, the trier must be long enough to reach the opposite end of the bag. When sampling bags vertically (weighing 100 kilograms or less), a partitioned trier must be used and the trier must be long enough to reach the bottom of the container or bag. When vertically sampling bags weighing greater than 100 kilograms, the trier may be used with or without partitions. The tier must be long enough to reach the bottom of the bag or tote.

Equipment - Nobbe trier

The Nobbe trier is a pointed tube with an oval opening near the pointed end. It is relatively compact, making it easy to transport. The risk of contamination is low as the trier is easy to keep clean. A Nobbe trier is suitable for sampling free-flowing product in bags, but only where the trier can reach to the centre of the bag. It may only be used horizontally and its use is limited to penetrable containers.

Photograph that shows three different sizes of Nobbe triers.
Three different sizes of Nobbe triers

Note: Facilities bagging grain after cleaning and processing may sample with a hand scoop off the top of the bag (100 kg or less) once filled, and prior to closing provided the following conditions are met:

  1. The same sampling tool is used to sample the entire lot.
  2. The sampling tool is of sufficient size (within the range of 50 to 200 grams) to ensure that the composite is a minimum of 1000 grams.
  3. The sampling of the lot is done at evenly spaced structured intervals at the intensity determined by the table Determining sampling intensity for static lots (bags).

4.21 Approved triers by crop type for grain

Canadian Grain Commission approved methods of manual sampling a static lot is done using a double sleeve trier or the Nobbe trier. The sampling device should not select the product by size or damage the product being sampled. The appropriate trier is selected by crop type as described in the following chart.

Approved triers by crop type for grain
Grain Trier size
Barley large (20 mm or greater)
Beans large (20 mm or greater)
Buckwheat large (20 mm or greater)
Canola small (8 mm to 14 mm)
Chickpeas large (20 mm or greater)
Corn large (20 mm or greater)
Flaxseed medium (15 mm to 19 mm)
Lentils medium (15 mm to 19 mm)
Mixed grain large (20 mm or greater)
Mustard small (8 mm to 14 mm)
Oats large (20 mm or greater)
Peas large (20 mm or greater)
Rapeseed small (8 mm to 14 mm)
Rye large (20 mm or greater)
Safflower large (20 mm or greater)
Soybeans large (20 mm or greater)
Soybeans (natto type) medium (15 mm to 19 mm)
Sunflower large (20 mm or greater)
Triticale large (20 mm or greater)
Wheat, Amber Durum large (20 mm or greater)
Wheat medium (15 mm to 19 mm)

4.22 Requirements for probing sacked grain

Caution: Safety precautions must be adhered to while sampling stacked grain sacks.

  1. Sacked grain refers to grain in any type of bag or tote.
  2. The facility/requestor must provide personnel to move sacks as necessary.
  3. All sacks in the lot must be accessible.
  4. All sacks in the lot must be of the same product, weight value and identification.
  5. All sacks must be tagged or stencilled with lot number/identification.

4.23 Procedure for sampling horizontally - double sleeve trier

  1. Carefully insert the trier diagonally on the horizontal plane into the container in the closed position until it reaches the opposite corner of the container. The outer tube opening must be facing upward. Care should be taken not to push the trier through the opposite corner of the container.
  2. Open the trier until the inner and outer openings are aligned, then agitate it slightly to allow the openings to fill.
  3. Close the trier gently (to the point of resistance) and then withdraw.
  4. Place each primary sample into a suitable clean container(s) (pan/pail) to allow for checking for uniformity.
  5. If necessary, reduce the sample to the appropriate size using a boerner-type divider.

Training video: Horizontal sampling with a double sleeve trier

4.24 Procedure for sampling vertically - double sleeve trier

  1. Insert the closed trier through the top of the container on an angle until it reaches the bottom of the container.
  2. Turn the inner sleeve until the inner and outer openings align and agitate the trier slightly to allow the openings to fill.
  3. Gently close the trier and withdraw.
  4. Collect the sample on a clean, long piece of paper or into a clean container that is the same length as the trier. (When sampled using partitions < 100 kilogram bags)
  5. Collect the sample in a clean container. (When sampled without using partitions > 100 kilogram bags)
  6. Check for uniformity with the primary samples already drawn before adding to the composite sample.
  7. If necessary, reduce the sample to the appropriate size using a boerner-type divider.

Training video: Vertical sampling with a double sleeve trier

4.25 Procedure for sampling - Nobbe trier

  1. Insert the trier gently into the centre of the bag with the trier opening facing downward and the trier tilted upwards at an angle of approximately 30 degrees to the horizontal.
  2. When sampling from the end of a bag, the opening of the trier must reach the centre of the bag. Insert the trier as close to the bottom edge of the bag as possible (i.e. below stitching).
  3. When sampling from the side, the opening of the trier must reach the opposite side of the bag. Insert the trier at the bottom edge of the bag such that the 30 degree angle is achieved.
  4. Rotate the trier through 180 degrees, bringing the slot to face upwards.
  5. Withdraw the trier with gentle agitation to help maintain an even flow of product into the collecting pail/bag.
  6. The trier must not be agitated without withdrawing.
  7. When sampling from the end, withdraw with decreasing speed so that the quantity of product obtained from successive locations increases progressively from the centre of the bag.
  8. When sampling from the side, withdraw with a constant rate of speed.
  9. Each primary sample must be placed into a suitable clean container/pan/pail/clear bag to allow for checking for uniformity.
  10. Readjust the bag fibres to close the gap by running the point of the trier across the hole a few times in opposite directions.

4.26 Determining sampling intensity for static lots (bags)

A composite sample must be a minimum of 1000 grams for submission to the Canadian Grain Commission. However, if the sample is to be utilized for multiple purposes, care must be taken to ensure the composite sample is sufficient in size to accommodate all necessary requirements. The numbers of primary samples indicated in this chart are minimums. If required, additional primary samples may be taken to construct a larger representative composite sample. All primary samples are to be drawn randomly throughout the entire lot.

Sampling intensity for static lots (bags) - up to the maximum lot size of 10 containers or 5000 bags per composite
Item Number of bags in lot Minimum number of primary samples to be taken Totes
1 1 - 20 All bags must be sampled All totes must be sampled-minimum 2 primary samples per tote. (maximum 300 totes per lot)
2 21 - 1000 6% of all bags in the lot, but not less than 20 samples randomly selected throughout
3 >1000 3% of all bags in the lot, but not less than 60 samples randomly selected throughout  

4.27 Sampling intensities of grain stored in totes

All totes must be sampled with a minimum of 2 primary samples per tote whether stream sampling (see stream sampling procedure defined above) while the tote is being filled, or probed after the tote is full.

Sampling intensity for totes
Item Number of bags in lot Minimum number of primary samples to be taken Totes
1 1 - 20 All bags must be sampled All totes must be sampled-minimum 2 primary samples per tote. (maximum 300 totes per lot)
2 21 - 1000 6% of all bags in the lot, but not less than 20 samples randomly selected throughout
3 >1000 3% of all bags in the lot, but not less than 60 samples randomly selected throughout  

Totes are grain sacks generally weighing 100 kilograms or more.

  1. All totes in the lot must be accessible and must be sampled.
  2. The maximum number of totes in a lot or sub-lot is limited to 300.
  3. Insert the closed probe into the tote to the maximum depth (bottom of the tote).
  4. Open the probe and agitate slightly to fill the inner tube.
  5. Close the probe slowly to the point where resistance is felt in order to minimize any damage to the sampled product.
  6. Extract the probe and release the sample onto a cloth, trough or into a sample container and examine it for uniformity. Based on the quality and quantity of sample taken by the probe, determine if multiple probes are required.  It is important to note that each tote in the lot must be sampled the same number of times to ensure equal representation within the lot.
  7. A minimum of 2 probes per tote is required.
  8. If necessary, reduce the composite sample to the appropriate size using the Boerner divider.

Note: Totes may be sampled as they are being filled using the procedure outlined for manual stream sampling as defined in section 4.1 of this guide. A minimum of two primary samples for each tote must be taken while being filled, at evenly spaced intervals. For example, one primary sample would be taken at the midway point, and one taken at completion.