Temperature Correction; Figure 12: Typical Crackmeter Calibration Sheet; Equation 4: Thermally-Corrected Displacement Calculation; Equation 5: Thermal Coefficient Calculation - Geokon 4420 Series Instruction Manual

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FIGURE 12: Typical Crackmeter Calibration Sheet

5.2 TEMPERATURE CORRECTION

's vibrating wire displacement transducers have a small coefficient of
GEOKON
thermal expansion. Correction may not be necessary in most cases. However, to
achieve maximum accuracy, there are corrections that you can apply.
Use the following equation to provide thermal correction of the instrument:
D = G(R – R ) + K(T
corrected 1 0 1

EQUATION 4: Thermally-Corrected Displacement Calculation

Where:
R
is the current reading
1
R
is the initial reading
0
G is the linear gauge factor
T
is the current temperature
1
T
is the initial temperature
0
K is the thermal coefficient (see Equation 5)
Tests have determined that the thermal coefficient, K, changes with the position
of the transducer shaft. The first step in the temperature correction process is
determination of the proper thermal coefficient based on the following equation:
K = ((R x M) + B) x G
1

EQUATION 5: Thermal Coefficient Calculation

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