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4.2. Temperature Correction
The Model 4450 Vibrating Wire Displacement Transducers have a small coefficient of
thermal expansion so in many cases correction may not be necessary. However, if
maximum accuracy is desired or the temperature changes are extreme (>10° C) corrections
may be applied.
The following equation applies;
Equation 3 - Thermally Corrected Displacement Calculation
Where:
R 1 is the current reading.
R 0 is the initial reading.
G is the calibration Factor.
T 1 is the current temperature.
T 0 is the initial temperature.
K is the thermal coefficient (see Equation 4).
Tests have determined that the thermal coefficient, K, changes with the position of the
transducer shaft. Hence, the first step in the temperature correction process is
determination of the proper thermal coefficient based on the following equation;
Where:
R 1 is the current reading.
TM is the multiplier from Table 3.
TB is the constant from Table 3.
G is the calibration factor, usually millimeters or inches per digit.
Model:
4450-3mm
4450-0.125
Multiplier (TM):
0.000520
Constant (TB):
3.567
Model:
4450-150 mm
4450-6"
Multiplier (TM):
0.000384
Constant (TB):
-0.3482
D corrected = ((R 1 - R 0 ) G) + ((T 1 - T 0 ) K)
K = ((R 1 TM) TB) G
Equation 4 - Thermal Coefficient Calculation
4450-12 mm
4450-0.5"
0.000375
1.08
4450-200mm
4450-8.0"
0.000396
-0.4428
Table 3 - Thermal Coefficient Calculation Constants
4450-25 mm
4450-50 mm
4450-1"
4450-2"
0.000369
0.000376
0.572
0.328
4450-300mm
4450-12"
0.000424
-0.6778
7
4450-100 mm
4450-4"
0.000398
0.0864
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