13
4.2 Temperature Correction
The Model 4430 Deformation Meter has a very small coefficient of thermal expansion; therefore,
in most cases correction is not necessary. However, if maximum accuracy is desired or the
temperature changes are extreme (>10 °C) corrections may be applied. The following equation
applies:
Dcorrected = ((R
1
- R
0
)
×
G) + ((T
1
- T
0
)
×
K) + L
C
Equation 3 - Thermally Corrected Deformation 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.
L
C
is the correction for the gauge length.
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:
Thermal Coefficient = ((Reading in Digits
×
Multiplier)
+
Constant)
×
Calibration Factor
Or
K = ((R
1
×
M)
+
B)
×
G
Equation 4 - Thermal Coefficient Calculation
See Table 2 for the Multiplier and Constant values used in Equation 4. The Multiplier (M) and
Constant (B) values vary for the stroke of the transducer used in the Deformation Meter.
Model:
4430-
3 mm
(0.125”)
4430-
12 mm
(0.5")
4430-
25 mm
(1")
4430-
50 mm
(2")
4430-
100 mm
(4”)
4430-
150 mm
(6”)
4430-
300 mm
(12”)
Multiplier (M):
0.000520 0.000375 0.000369 0.000376 0.000398 0.000384 0.000424*
Constant (B):
3.567
1.08
0.572
0.328
0.0864
-0.3482 -0.6778*
Transducer
Length (L):
267 mm
10.5”
267 mm
10.5"
267 mm
10.5"
292 mm
11.5"
393 mm
15.49”
510.5 mm
20.1”
715.2 mm
28.2”
Table 2 - Thermal Coefficient Calculation Constants
* Calculated