Moisture determination guidelines for model 919/3.5" and 393/3.5" moisture meters

The CGC uses the Model 919/3.5" moisture meter for official testing of grain samples and operates over 100 of these meters at locations across Canada. The CGC's Grain Research Laboratory provides conversion tables for use with these meters.

Every two weeks, the GRL performs a check test on all CGC meters. The check test is performed to ensure that all CGC meters operate within our allowable tolerances of +0.2 percent moisture.

Check test samples are made available to the head offices of all major grain companies. Companies use these to compare the results of one of their meters with all CGC meters. This meter can be used as a standard if a company wishes to establish its own check test system.

Before you begin moisture testing

• Ensure the sample is free of dockage.
• Ensure the temperature of the sample is between 11°C and 30°C.
• If there is visible moisture on the surface of the grain, leave the grain in a sealed plastic container at room temperature until the moisture has been absorbed into the grain.
• Ensure your scale is accurate. Follow Tips for effective use of your Model 919/3.5" or 393/3.5" moisture meters.
• Ensure you have the right conversion tables.

Tips for effective use of your Model 919/3.5" or 393/3.5" moisture meters

• Each day that you use your scale and thermometer, check them to verify their accuracy.
  • For scales, use a set of weights or weigh a sample of a known weight.
  • For thermometers, ensure there are no separations in the mercury or alcohol columns.
• Determine the temperature of each sample and record it.
  • Test samples when their temperature is between 11°C and 30°C.
• Verify the calibration of the meter.
  • At least every 10 minutes during continuous use
  • After each sample with intermittent use
• Do three tests on each sample.

Maintaining the accuracy of your moisture meter

• Do not interchange grain cells between meters. The cell and body are calibrated as a unit and errors may occur if they are interchanged.
• Keep the test cell clean.
• Check the cell connection to the meter occasionally. To do this,
  1. Put the meter in the CAL position.
  2. Wiggle the test cell. If the meter needle moves sharply, one or both of the cell contacts needs replacing. List of meter service locations.
• Check the electronic alignment of a meter at least once a year. To do this, you create three subsamples that give specified readings on your meter, and then you retest these samples on another meter.
  1. Create three subsamples of different sizes. The first should give a meter reading of approximately 75, the second, approximately 50, and the third, approximately 15. Keep the sample temperature the same when using the two meters. Keep the samples in moisture proof containers between tests.
  2. Check these three samples with another meter (preferably a CGC meter) to see if they give similar results

Calibrating the meter

If you are testing samples continuously, check the calibration at least every 10 minutes.

If you are testing samples intermittently, check the calibration before each sample.

1. Move the On-Off switch to On.
2. Turn the function knob to Cal.
3. Turn the large knob on the right side of the meter until dial reading 53 is directly beneath the hairline. Dial reading 53 has a red arrow marked Cal.
4. Rotate the small knob on the left side of the meter until the meter needle reaches the lowest possible position on the left side of the meter scale.
5. Turn the function knob to Op.

Measuring temperature

If you are testing samples continuously, check the calibration at least every 10 minutes.

If you are testing samples intermittently, check the calibration before each sample.

1. Place a weighed and cleaned sample of grain in the warm-up container or dump cylinder.
2. Insert the thermometer into the grain sample.
   Important : Make sure that the bulb of the thermometer does not touch the container walls.
3. Wait one to three minutes to stabilize the thermometer.
4. Record the temperature of the sample.

If the temperature is from 11°C to 30°C

Then determine the moisture content.

If the temperature is under 11°C or over 30°C

Then keep the sample in an airtight container until its temperature is from 11°C to 30°C.

Important: Wait one to three minutes to stabilize the thermometer.

Procedures for determining moisture content

1. Read Before you begin moisture testing.
2. Calibrate the meter, if required. Follow Calibrating the meter.
3. Set the function knob on the moisture meter to Op.
4. Record the temperature of the grain. Follow Measuring temperature.

Taking the reading

1. Place the loaded dump cylinder on the measuring cell.
2. Push the release button, which dumps the sample into the test cell.
   Important : If kernels are in contact with the surface of the inverted cone portion of the centre post, the sample is probably light weight, and the meter reading will be inaccurate. Follow Estimating moisture content for light weight wheat and barley samples.
3. Remove the empty dump cylinder from the measuring cell.
4. Turn the dump cylinder over, to prepare it for the next sample.
5. Turn the large knob on the right side of the meter until the needle reaches the lowest position on the left of the meter scale.
6. Record the dial reading directly beneath the hairline, to the nearest 0.5 of a division.
7. Return the weighed grain sample to the dump cylinder. Make sure that you do not lose any kernels.
8. Repeat steps 5 to 11 two more times. That is, take three meter readings.

Determining the moisture content

1. Calculate the average of the three meter readings.
2. Look up the percentage moisture on the conversion table for the grain.

If the reading is higher than those on the conversion chart then follow Estimating moisture content for high moisture samples.

Estimating moisture content for lightweight wheat, oats and barley samples

Use these procedures for lightweight wheat, oats and barley samples.

• Canada Western Red Spring (CWRS) wheat is light weight if it is less than 66 kg/hL or 320 g/0.5 L.
• Oats are lightweight if its test weight is less than 48 kg/hL or 220 g/0.5 L.
• Barley is lightweight if its test weight is less than 52 kg/hL or 250 g/0.5 L.
• Samples of wheat, oats and barley are also considered lightweight if grain touches the surface of the inverted cone portion of the cell post in the measuring cell.

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

Canada Western Red Spring (CWRS) wheat, oats and barley

Conversion tables are available for lightweight CWRS, oats and barley. See Conversion tables for use with model 919/3.5 and 393/3.5 moisture meters.

Other wheats

These are the procedures for estimating the moisture content of lightweight samples of Canada Western Soft White Spring (CWSWS), Canada Western Red Winter (CWRW), and Canada Western Amber Durum (CWAD), Canada Western Extra Strong (CWES), and Canada Prairie Spring Red or Canada Prairie Spring White (CPSR and CPSW) wheat.

1. Test a 225-gram sample using the Procedures for determining moisture content.
2. Determine the moisture using Moisture Conversion Table Number 9 (Red Spring Wheat, test weight less than 66 kilograms/hectolitres).
3. Subtract or add depending upon the correction factor for the appropriate class by moisture range according to the following Correction factors table.

Correction factors

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

Examples

Step 1

Use a 225-gram sample with the appropriate temperature.

Example

A 225-gram sample of light weight CWSWS wheat gives a meter reading of 40.0 at 15°C.

Step 2

Determine the moisture using Moisture Conversion Table No. 9 (Canada Western Red Spring wheat, weight less than 66 kg/hL).

Example

Conversion Table Number 9 (CWRS, test weight less than 66 kilograms/hectolitre) gives a percentage moisture of 16.2.

Step 3

Add or subtract the correction factor from the chart for the appropriate class according to the moisture range.

Example

The correction factor from the Correction factors table is -0.1. The corrected moisture for the light weight sample is (16.2 - 0.1) or 16.1%

Estimating moisture content for high moisture samples

If the meter reading on a sample is higher than those on the conversion table, use the following procedure to estimate moisture content.

1. Accurately weigh out a portion of the original sample larger than the quantity required for testing. For example, use 300 grams of red spring wheat, not 250 grams as required for meter testing.
2. Spread the sample on paper and let it dry at room temperature.
3. Reweigh the sample.
4. Calculate the percentage weight loss.
   A = original sample weight
   B = sample weight after air drying
   Percentage loss in weight during air drying = 100 (A - B) / A = C
5. Mix the sample thoroughly.
6. Weigh out the amount required for a meter test.
7. Determine the temperature of the sample.
8. Follow Procedures for determining moisture content.
9. Determine the total moisture content of the sample using the following formula.
   C = percentage by weight of moisture loss on air-drying (step 4)
   D = moisture content determined by meter (step 8)
   Percentage moisture by weight = [(100 - C) x (D/100)] + C
10. Report the result to the nearest 0.1%.

Calculator for estimating moisture content for high moisture samples

Estimating moisture content for beans with no conversion tables

For beans, the damp moisture range is over 18%.

Azuki beans

1. Use a 250-gram sample.
2. Use the CGC Cranberry Bean Conversion Table Number 2.
3. Subtract 2.5 from the table result.

Dutch brown beans

1. Use the CGC Pea Bean Conversion Table Number 2
2. Subtract 1.1 from the table result.

Great northern white beans

1. Use the CGC Pea Bean Conversion Table Number 2
2. Subtract 1.4 from the table result.

Pink beans

1. Use the CGC Pea Bean Conversion Table Number 2
2. Subtract 1.1 from the table result.

Eastern white kidney beans

1. Use the Dark Red Kidney Bean Conversion Table Number 2 and add 0.5 to the result.
2. Read the percentage moisture directly from the table.

Light red kidney beans

1. Use the Dark Red Kidney Bean Conversion Table Number 2.
2. Read the percentage moisture directly from the table.

Small red beans

1. Use a sample size of 250 grams.
2. Take a reading using Proceduces for determining moisture content.
3. Apply the regression formula, where T is the sample temperature in degrees Celsius.
   • Percentage moisture = 0.155 x Meter Reading + 8.03 + {0.1x (22 - T)}

Otebo Beans

1. Use the CGC Pea Bean converion Table Number 2.
2. Subtract 0.3 from the table result.

Kintoki Beans

1. Use the Dark Red Kidney Bean Conversion Table Number 2.
2. Read the percentage moisture directly from the table.

Example

The Pea Bean Conversion Table Number 2 shows a sample of 250 grams is required.

A sample of Great northern white beans shows a meter reading of 25 at 18°C. According to the table, the moisture content for Pea beans at this reading is 13.6%.

To adjust this moisture content for Great northern white beans, subtract 1.4.

The moisture content (of the beans) is 13.6 - 1.4, or 12.2.

Moisture content disputes

Most times, you and your elevator operator probably agree on the moisture content of grain delivery, as you do with grade and dockage assessment. When you cannot agree, you or the operator has the right to obtain a binding decision from the CGC. Payment for the grain must be made according to the CGC's decision.

To take advantage of this service, called Subject to Inspector's Grade and Dockage-moisture content only, the following procedure must be followed. The CGC charges a fee for this service.

1. While the grain is being delivered to the elevator, the operator must take a representative sample in the presence of the owner or the owner's representative, and the sample must be satisfactory to that person. The sample is not kept unless the owner or the owner's representative requests it. The representative sample must
   • Weigh at least 300 grams
   • Be placed in an unbreakable airtight container supplied by the operator of the elevator
   • Be properly identified with the owner's name
   • Be marked Subject to Inspector's Grade and Dockage-moisture content only
2. The elevator operator issues an interim primary elevator receipt.
3. The elevator operator sends the sample directly to CGC Industry Services. The sample must
   • Be accompanied by a fully completed CGC form IS-12-7 that includes the interim primary elevator receipt number
   • Have sufficient postage, if sent by mail
4. CGC Industry Services communicates the official result of the moisture test, which is final and binding, to both the elevator operator and the owner.

Contacts

• Determining moisture content contacts:
  • List of meter service locations
  • Moisture technician, Canadian Grain Commission
  • Inspection Services contacts