MODEL 4420 VIBRATING WIRE CRACKMETER
| MODEL 4420-3 LOW PROFILE CRACKMETER |
27
8.
Connect the cable to the readout box. Use the POS button to choose
position E and the MODE button to select microstrain (μ
ε
). The calibration
sheet indicates the minimum and maximum readings recommended based
on the setpoints utilized during the calibration process.
9.
Set the zero position by turning the oval point set screw until the desired
reading is achieved. The correct zero reading can be determined by the
following:
■
If the set screw end of the gauge is anticipated to move up only in
relationship to the 4150 gauge, set the zero reading near the 0.0 mm
displacement according to the calibration sheet (about 2000 digits).
■
If the set screw end of the gauge is anticipated to only move down in
relationship to the 4150 gauge, set the zero reading near the 25.4 mm
displacement according to the calibration sheet (about 12,000 digits).
■
For unknown movement or to set the gauge at midrange, set the zero
reading between the 10.2 mm and 15.2 mm displacement according to
the calibration sheet (about 7000 digits).
Note:
The above zero reading suggestions are given assuming the two
sides of the joint are on the same plane when the instrument is installed. If
there is a major discrepancy between the two sides, contact geokon to
determine if a custom solution is required.
10. Once the reading is set, tighten the locknuts to secure the set screw.
11. In areas of high traffic, the gauge should be protected by a cover plate. For
more information, see Section 3.2.
E.2
SPECIFICATIONS
The table below lists the specifications.
TABLE 11:
Model 4420-3 Crackmeter Specifications
Notes:
1
Depends on the readout, above figure pertains to the GK-404 Readout.
2
System Accuracy takes into account hysteresis, nonlinearity, misalignment,
batch factor variations, and other aspects of the actual measurement program.
System Accuracy to 1.0% FS may be achieved through individual calibration of
each crackmeter.
Range:
11:
3000
µ
ε
Resolution¹
0.4
µ
ε
Calibration Accuracy
0.1% FS
System Accuracy
2
2.0% FS
Stability:
0.1% / yr
Linearity:
2.0% FSR
Thermal Coefficient
12.2
µ
ε
/°C
Temperature Range:
-20 to +80 °C
-5 to +175 °F
Readout Position
E
Display Units
microstrain (
µ
ε
)
Frequency Range:
1400-3500 Hz
Coil Resistance:
+50
Ω
Dimensions (gauge)
57.2 x 6.4 mm
2.250 x 0.250"
Dimensions (coil)
19.1 x 6.4 mm (diameter)
0.750 x 0.250" (diameter)
Mid-Range Reading
2500
µ
ε
Minimum Reading
1000
µ
ε
Maximum Reading
4000
µ
ε