5.1 Gauge calibration is performed for the following purposes:
5.1.1 To formulate a mathematical equation, or density calibration equation, that relates the gauge density system response (the “density count”) to the soil-equivalent density of the standard on which this response is elicited.
5.1.2 To formulate a mathematical equation, or water content calibration equation, that relates the gauge water content system response (the “water content count”) to the water mass per unit volume value of the standard on which this response is elicited.
5.1.3 To ensure that the gauge has an in-place water mass per unit volume gauge precision level that is consistent with typical gauge response.
5.2 Gauge verification is performed for the following purposes:
5.2.1 To indicate to the party or agency performing the verification when the mathematical relationship between the in-place density reading indicated by the gauge and the corresponding gauge density test count needs to be adjusted so that the gauge calibration meets the required level of measurement uncertainty.
5.2.2 To indicate to the party or agency performing the verification when the mathematical relationship between the water mass per unit volume indicated by the gauge and the corresponding gauge water content test count needs to be adjusted so that the gauge calibration meets the required level of measurement uncertainty.
5.2.3 Gauge verification and calibration require specialized training and equipment. Gauge calibration and verification should only be conducted by those trained in the proper operation of the gauge, the calibration or verification standards, and any tables, charts, graphs, or computer programs required for the proper execution of these operations.
Note 1: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
1.1 This guide describes the process and objective of calibrating the density system of a nuclear surface moisture and density gauge, or formulating the mathematical relationship between the density system response (the “density count”) of a nuclear surface moisture and density gauge and the corresponding density value of the density standard upon which the density system response was observed.