Geokon 4400, Instruction Manual

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8
4. DATA REDUCTION
4.1. Deformation Calculation
The basic units utilized by Geokon for measurement and reduction of data from Vibrating
Wire Jointmeters are "digits". The units displayed by the GK-401, GK-402, and GK-403 in
position "B" are digits. Calculation of digits is based on the following equation;
Digits
Period






 

2
3
1
10
or
Digits Hz
 

2 3
10
Equation 1 - Digits Calculation
To convert digits to deformation the following equation applies;
Deformation

(Current Reading - Initial Reading)

Calibration Factor

Conversion Factor
or
D = (R
1
- R
0
)

G

F
Equation 2 - Deformation Calculation
Where; R
1
is the Current Reading.
R
0
is the Initial Reading usually obtained at installation (see section 2.4).
G is the Calibration Factor, usually in terms of millimeters or inches per digit.
F is an engineering units conversion factor (optional), see Table 1.
From

To

Inches Feet Millimeters Centimeters Meters
Inches 1 12 0.03937 0.3937 39.37
Feet
0.0833 1 0.003281 0.03281 3.281
Millimeters 25.4 304.8 1 10 1000
Centimeters 2.54 30.48 0.10 1 100
Meters
0.0254 0.3048 0.001 0.01 1
Table 1 - Engineering Units Conversion Multipliers
For example, the Initial Reading (R
0
) at installation of a jointmeter with a 12 mm transducer
range is 3150 digits. The Current Reading (R
1
) is 6000. The Calibration Factor is 0.00356
mm/digit. The deformation change is;
D = (6000

3150)

0.00356 = +10.146 mm
Note that increasing readings (digits) indicate increasing extension.