25
Geokon Model
Gauge Type
Description
4000
3
Strain Gauge
4100
1
Strain Gauge
4200
3
Strain Gauge
4204
6
Strain Gauge
4202/421X
1
Strain Gauge
4300BX
1
BX Borehole Stressmeter
4300EX
5
EX Borehole Stressmeter
4300NX
1
NX Borehole Stressmeter
4400
1
Embedment Jointmeter
4420
1
Crackmeter
4450
1
Displacement Transducer
4500
1
Piezometer
4600/4651/4675
1
Settlement Systems
4700
1
Temperature Transducer
4800
1
Pressure Cell
4850
1
Low Pressure Piezometer
4900
1
Load Cell
4910/4911/4912
1
Load Bolts
Table 2 - Vibrating Wire Gauge Types
Type Measurement
Type
Description
Output
Units
Linear Range
Polynomial Range
0
Vibrating Wire
Test frequency sweep, 400-4500 Hz
Digits
160 to 20250
0.160 to 20.250
1
Vibrating Wire
Middle frequency sweep, 1400-3500 Hz
Digits
1960 to 12250
1.960 to 12.250
2
Vibrating Wire
High frequency sweep, 2800-4500 Hz
Digits
7840 to 20250
7.840 to 20.250
3
Vibrating Wire Very low frequency sweep, 400-1200 Hz
Digits
160 to 1440
0.160 to 1.440
4
Vibrating Wire
Low frequency sweep, 1200-2800 Hz
Digits
1440 to 7840
1.440 to 7.840
5
Vibrating Wire Very high frequency sweep, 2500-4500 Hz Digits
6250 to 20250
6.250 to 20.250
6
Vibrating Wire
Low frequency sweep, 800-1600 Hz
Digits
640 to 2560
0.640 to 2.560
7-84
Not assigned
85
External
thermistor
Reads the thermistor encapsulated in the
Vibrating Wire instrument.
°C
-50 to +80
-50 to +80
86
Internal
thermistor
Reads the thermistor installed in the LC-2
Printed Circuit Board (PCB)
°C
-50 to +80
-50 to +80
87 Main battery: 12V
Reads the main 12V battery voltage
VDC
0 to 15
0 to 15
88-94
Not assigned
95 3V lithium battery
Reads the 3V lithium RTC battery
VDC
0 to 3.5
0 to 3.5
97 Main battery: 3V
Reads the main 3V battery voltage
VDC
0 to 7.5
0 to 3.5
Table 3 - Gauge Type Descriptions
NOTE: When using the Polynomial conversion method, the default reading units for a vibrating
wire instrument is the frequency squared multiplied by 10
-6
. For example, an instrument reading
3000Hz will output a value of “9.000” when A is entered as “0”, B is “1” and C is “0”. However,
typical calibration units for vibrating wire instruments are frequency squared multiplied by 10
-3
.
To adjust for this discrepancy between LC-2 expected units and calibration units
multiply the A
coefficient by 1,000,000 and the B coefficient by 1000. The A and B coefficients can be
found on the supplied calibration certificate.
The
C
coefficient should be calculated based on
an actual field reading.
The above multiplication is
only
necessary if the datalogger is being set
up via text commands (see Section 3.5 for an example setup using text commands)
AND
the
gage conversion is set for polynomial. When using LogView to setup the datalogger
configuration, the multiplication is performed by LogView. Refer to the appropriate sensor
manual for more information on how to calculate the
C
coefficient.