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Gilson Company, Inc.
4.0 ACCURACY
When testing soils, it is recommended that the procedures in ASTM D 4944, Standard Test Method for Field Determination
of Water (Moisture) Content of Soil by the Calcium Carbide Gas Pressure Tester Method be followed. This will insure accurate
and reliable results. For optimum accuracy with most materials, the Aqua-Check results should be correlated with oven-dry
tests for each material as shown in this summary. This simple procedure is outlined in detail in D 4944.
1. Select several samples of the material to be tested having a wide range of water content.
2. Carefully Divide each sample into two representative specimens.
3. Taking care to not lose moisture during handling, run a test on one specimen in the Aqua-Check, and record the gauge
reading. Oven dry the other specimen according to the procedure and calculate the percent moisture.
4. Plot the oven-dry moistures on a graph vs. the gauge readings and draw a best-fit curve through the points. A wide
scatter in the points may indicate operation errors or that the material is not suitable for this comparison.
5. When testing, find the point on the graph where the gauge reading intersects the correlation curve and record that
value as the corrected percent.
Exceptionally cool or warm ambient temperatures may cause fluctuations in test results. Repeated testing or hot weather
may heat up the vessel body, and show test results that are artificially high. Allow the vessel to cool down before further
testing. In cold weather, it may help to run two or three tests in rapid succession to warm up the vessel.
The maximum recommended particle size is 3/4in (20mm). Some test methods may have a smaller size limit.
Typical Calibration Curve
Calcium Carbide Tester
Gauge Reading, Calcium Carbide Tester
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Gilson Aqua-Check Moisture Tester: MA-26X
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