Moisture determination guidelines for Canadian grains

Moisture meter models

The following moisture determination guidelines can be used by producers and elevator operators who use the model 919/3.5” or equivalent moisture meter.

For moisture meters using the Unified Grain Moisture Algorithm (UGMA), models AM5200-A and GAC2500, please follow the manufacturer’s directions on the use and maintenance of the moisture meter.

Moisture testing steps for model 919/3.5" or equivalent moisture meters

Step 1 Prepare for moisture testing

  • Ensure the sample is free of dockage.
  • Check your thermometer to make sure it is working properly.
  • Ensure the temperature of the sample is between 11°C and 30°C.
  • If you see moisture on the surface of the grain, leave it in a sealed plastic container at room temperature until the moisture has been absorbed into the grain.
  • Check your scale’s accuracy with a set of weights or a sample of known weight.
  • Ensure you use the correct conversion table for the model 919/3.5” or equivalent moisture meter or enter the data into our moisture calculator.

Step 2 Calibrate model 919/3.5" or equivalent moisture meters

How often you test samples influences how often you need to check the calibration of your moisture meter.

  • If you are continuously testing samples, calibrate the moisture meter at least every 10 minutes.
  • If you are intermittently testing samples, calibrate the moisture meter before testing each sample.

To calibrate a model 919/3.5" or equivalent moisture meter:

  • Move the ON-OFF switch to ON.
  • Turn the function knob to CAL.
  • Turn the large knob on the moisture meter’s right side until the dial reading 53 is directly beneath the hairline. Dial reading 53 has a red arrow marked CAL.
  • Rotate the small knob on the moisture meter’s left side until the meter needle reaches the lowest possible position on the meter movement.
  • Note: For Sunflower and Safflower a dial reading of 73 is used for calibration.

Step 3 Measure temperature of grain samples

  • Use a sample of grain that has been weighed and cleaned. You will find the required sample weight in the moisture conversion table or by using the moisture calculator for model 919/3.5” or equivalent.
  • Place the sample in the warm-up container or dump cylinder.
  • Insert a thermometer in the grain sample. Important: Make sure the thermometer’s bulb does not touch the container walls.
  • Wait 1 to 3 minutes to stabilize the thermometer.
  • Record the temperature of the sample:
    • If the temperature is from 11°C or 30°C, determine the moisture content.
    • If the temperature is under 11°C or over 30°C, keep the sample in an airtight container until its temperature is between 11°C and 30°C.
  • Using the average dial reading and sample temperature, review the percent moisture on the conversion table for that grain.

Step 4 Take a meter reading

  • Set the function knob on the moisture meter to OP.
  • Record the grain sample temperature.
  • Place the loaded dump cylinder on the measuring cell.
  • Push the release button to dump the sample into the test cell.
    • Important: If grain contacts the surface of the centre post’s inverted cone portion, the sample is probably lightweight. This means the moisture meter’s reading will be inaccurate. You must estimate the moisture content for lightweight samples.
  • Remove the empty dump cylinder from the measuring cell.
  • Turn the dump cylinder over to prepare it for the next sample.
  • Turn the large knob on the meter’s right side until the needle reaches the lowest position on the meter movement.
  • Record the dial reading directly beneath the hairline to the nearest 0.5 of a division.
  • Return the weighed grains sample to the dump cylinder. Make sure that you do not lose any kernels.
  • Repeat twice to take a total of 3 dial readings.

Step 5 Determine moisture content of grain

Our moisture calculator or conversion tables can be used to estimate the moisture content.

Calculator

Use the moisture content calculator for moisture conversion (calculator was created by using information directly from the moisture conversion tables for grains).

Use the conversion tables to estimate the moisture content.

  • Calculate the average of 3 meter readings.
  • Convert the average meter reading and sample temperature to percent moisture using the conversion table for that grain.
  • If the reading is higher than those on the conversion table, you must estimate moisture content for high-moisture samples.
  • For beans without a conversion table, estimate the moisture content.

Maintain accuracy of model 919/3.5" or equivalent moisture meters

  • Avoid switching grain cells between moisture meters. A moisture meter cell and body are calibrated as one unit. Errors may occur if they are interchanged.
  • Keep the test cell clean.
  • Occasionally check the connection between the cell and the moisture meter. To do this:
    • Put the moisture meter in the CAL position.
    • Wiggle the test cell. If the moisture meter’s needle moves sharply, 1 or both of the cell contacts need to be replaced.
  • Check the moisture meter’s electronic alignment at least once a year. To do this:
    • Create 3 samples. On your moisture meter, each sample should give a different reading: approximately 75, 50 and 15.
    • Keep the sample temperature the same when testing the 2 moisture meters. Store samples in moisture-proof containers between tests.
    • Retest these samples on another moisture meter to see if the results are similar.

Lightweight samples (model 919/3.5” or equivalent)

Weight at which grain is lightweight

Type of grain Weight
Wheat, Canada Western Red Spring (CWRS) Less than 66 kg/hL or 320 g/0.5L
Oats Less than 48 kg/hL or 220 g/0.5L
Barley Less than 52 kg/hL or 250 g/0.5L

Samples of wheat, oats and barley are considered lightweight if grain touches the surface of the inverted cone portion of the centre post in the measuring cell.

This drawing shows the measuring area of the centre post in a test cell.
The measuring area of the centre post in a test cell.

Estimate moisture content for lightweight samples of Wheat, Canada Western Red Spring, oats and barley

Use conversion tables to estimate moisture content for lightweight Canada Western Red Spring wheat, oats and barley samples. These tables are for use with model 919/3.5" or equivalent moisture meters.

Estimate moisture content for lightweight wheat classes other than Wheat, Canada Western Red Spring

These procedures are for estimating the moisture content of lightweight samples of the following wheat classes:

  • Wheat, Canada Western Soft White Spring (CWSWS)
  • Wheat, Canada Western Red Winter (CWRW)
  • Wheat, Canada Western Amber Durum (CWAD)
  • Wheat, Canada Western Extra Strong (CWES)
  • Wheat, Canada Prairie Spring Red (CPSR)
  • Wheat, Canada Prairie Spring White (CPSW)

To estimate moisture content:

  • Test a 225-gram sample within the acceptable temperature range (11°C to 30°C).
  • Determine the moisture using the conversion table Wheat, Canada Western Red Spring, less than 66 kg/hL.
  • Subtract or add the correction factor.

Correction factors for lightweight wheat classes other than Wheat, Canada Western Red Spring

Correction factors for different wheat classes based on moisture content range
Moisture range % CWSWS CWRW CWAD CWES CPSR/CPSW HWS
10.0 – 12.0 0.0 -0.1 -0.4 -0.2 0.2 -0.1
12.1 – 14.0 -0.1 -0.3 -0.6 -0.3 0.0 -0.1
14.1 – 16.0 -0.3 -0.5 -0.8 -0.4 -0.3 -0.1
16.1 – 18.0 -0.4 -0.6 -0.9 -0.5 -0.5 -0.2
18.1 – 20.0 -0.6 -0.8 -1.1 -0.6 -0.7 -0.2

Example

Using a 225-gram sample of lightweight Wheat, Canada Western Soft White Spring at 15°C.

  • Sample gives a meter reading of 40.0 on a Model 919/3.5” moisture meter, which corresponds to 16.2% moisture on the Wheat, Canada Western Red Spring, less than 66 kg/hL conversion table.
  • The correction factor for Wheat, Canada Western Soft White Spring is -0.4. The corrected moisture for the lightweight sample is 16.2 minus 0.4 or 15.8%.

High-moisture samples

This calculator is used when the moisture content of the grain is higher than the limit for your moisture meter. For UGMA (Unified Grain Moisture Algorithm) type moisture meters, a sample exceeding the limits will give an error message stating that the moisture is too high. For model 919/3.5” or equivalent moisture meters, the limit is listed on our moisture conversion tables.

Calculator

Moisture content of high-moisture grain can be calculated using our moisture content calculator for high moisture grain or by using the following steps.

  1. Take a sample of grain and ensure it is free of dockage.
  2. Weigh out a larger portion of the original sample than is required for testing on your moisture meter and record the weight (A).
  3. Spread the sample in a single layer on paper. Let the sample dry at room temperature.
  4. Weigh the air-dried sample and record the weight (B).
  5. Calculate the percentage weight loss using this formula:
    • C = 100(A B) A
    • A = Original sample weight
    • B = Sample weight after air drying
    • C = percentage of weight lost during air drying
  6. Mix the sample thoroughly.
  7. Measure the moisture content of your air-dried sample on your moisture meter. For model 919/3.5” or equivalent moisture meters, follow the instructions to calibrate your model 919/3.5" or equivalent moisture meter and to convert your meter reading to a moisture value using the conversion tables or calculator.
  8. Repeat step 7 twice more for a total of 3 moisture measurements.
  9. Calculate the average of the 3 meter measurements (D).
  10. Determine the total moisture content of the sample using this formula:
    • E = [ (100 C) x ( D 100 ) ] + C
    • C = percentage of weight lost during air drying (found in Step 5)
    • D = moisture content determined by the moisture meter (found in Step 9)
    • E = total moisture content
  11. Report the result to the nearest 0.1%.

Beans with no conversion tables (model 919/3.5” or equivalent)

The damp moisture range for beans is over 18%. These procedures are for the model 919/3.5" or equivalent moisture meter.

Dutch Brown Beans

  • Use the Canadian Grain Commission conversion table number 3 for Pea Beans.
  • Subtract 0.8 from the table result.

Kintoki Beans

  • Use the Canadian Grain Commission conversion table number 2 for Beans, Dark Red Kidney.
  • Read the percentage moisture directly from the table.

Pink Beans

  • Use the Canadian Grain Commission conversion table number 3 for Pea Beans.
  • Subtract 0.8 from the table result.

Yellow Beans

  • Use the Canadian Grain Commission conversion table number 1 for Beans, Light Red Kidney.
  • Read the percentage moisture directly from the table.

Example using Pink Beans

Use the Canadian Grain Commission conversion table number 3 for Pea Beans. According to the conversion table, a 250-gram sample is required.

A sample of Pink Beans at 18°C gives a reading of 25 on a moisture meter. According to the conversion table, the moisture content of Pea Beans is 13.2% for a dial reading of 25.

To adjust the moisture content for Pink Beans subtract 0.8% from 13.2%. The actual moisture content for Pink Beans is 12.4%.

Official moisture testing

The Canadian Grain Commission uses several different instruments for official moisture testing of grain samples:

  • Perten Model AM5200-A moisture meter
    • Unified Grain Moisture Algorithm (UGMA) technology
  • Foss Infratec 1241
    • Near Infrared by transmittance
    • For use with Wheat and Barley (less than or equal to 14.5% moisture)

The Canadian Grain Commission monitors all calibrations for grains regulated under the Canada Grain Act on the 919 and UGMA-type moisture meters on an annual basis (depending on sample availability). However, changes are made to the calibrations where there is a consistent difference outside assigned tolerances to the results obtained by the reference procedure for at least 3 years. Changes may be made sooner on a case-by-case basis and after other testing has been completed.

Calibrations on moisture instruments focus on the normal trading moisture range for that particular commodity in order to be as accurate as possible to the reference result. Once outside that range, such as for wet or dry samples, the measurement variation increases.

Calibration development for both model 919 and UGMA-type moisture meters are based on best-fit regressions to our reference oven results. This means that in choosing the best calibration, the overall fit of the regression is evaluated, not specific samples.

Canadian Grain Commission moisture meters are checked for precision every month. The analytical services moisture laboratory maintains a check test system to ensure that all of our moisture meters operate within allowable tolerances of plus or minus 0.2% moisture.

Check test samples are made available to all grain companies so they may:

  • Compare their standard meter results with Canadian Grain Commission moisture meter results.
  • Use those standard meters to establish their own check test systems.

Definitions

Class
Class, in respect of grain, means any variety or varieties of grain designated by order of the Canadian Grain Commission as a class for the purposes of the Canada Grain Act.
Dockage
According to the Canada Grain Act, dockage is material that must be removed from grain by the use of approved cleaning equipment so that the grain can be assigned a grade. Once it has been removed from the grain, dockage is called screenings.
Moisture content
The measure of water content of grain. Grain that is within acceptable limits of moisture is referred to as a straight grade. With increasing moisture content, grain may be referred to as tough, damp, moist or wet.

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