Geokon 4430 User manual

Instruction Manual
Model 4430
VW Deformation Meter
No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon®.
The information contained herein is believed to be accurate and reliable. However, Geokon®assumes no responsibility for errors,
omissions or misinterpretation. The information herein is subject to change without notification.
Copyright © 1988-2019 by Geokon®
(Doc Rev L, 1/09/2019)

Warranty Statement
Geokon warrants its products to be free of defects in materials and workmanship, under normal
use and service for a period of 13 months from date of purchase. If the unit should malfunction,
it must be returned to the factory for evaluation, freight prepaid. Upon examination by Geokon,
if the unit is found to be defective, it will be repaired or replaced at no charge. However, the
WARRANTY is VOID if the unit shows evidence of having been tampered with or shows
evidence of being damaged as a result of excessive corrosion or current, heat, moisture or
vibration, improper specification, misapplication, misuse or other operating conditions outside of
Geokon's control. Components which wear or which are damaged by misuse are not warranted.
This includes fuses and batteries.
Geokon manufactures scientific instruments whose misuse is potentially dangerous. The
instruments are intended to be installed and used only by qualified personnel. There are no
warranties except as stated herein. There are no other warranties, expressed or implied, including
but not limited to the implied warranties of merchantability and of fitness for a particular
purpose. Geokon is not responsible for any damages or losses caused to other equipment,
whether direct, indirect, incidental, special or consequential which the purchaser may experience
as a result of the installation or use of the product. The buyer's sole remedy for any breach of this
agreement by Geokon or any breach of any warranty by Geokon shall not exceed the purchase
price paid by the purchaser to Geokon for the unit or units, or equipment directly affected by
such breach. Under no circumstances will Geokon reimburse the claimant for loss incurred in
removing and/or reinstalling equipment.
Every precaution for accuracy has been taken in the preparation of manuals and/or software,
however, Geokon neither assumes responsibility for any omissions or errors that may appear nor
assumes liability for any damages or losses that result from the use of the products in accordance
with the information contained in the manual or software.

TABLE of CONTENTS
1. INTRODUCTION ...................................................................................................................................................1
1.1 THEORY OF OPERATION.......................................................................................................................................1
2. INSTALLATION ....................................................................................................................................................2
2.1 PRELIMINARY TESTS............................................................................................................................................2
2.2 SENSOR ASSEMBLY ..............................................................................................................................................2
2.3 DEFORMATION METER INSTALLATION ................................................................................................................4
2.3.1 Installation in Boreholes.............................................................................................................................4
2.3.2 Installation in Mass Concrete .....................................................................................................................5
2.3.3 Installation in Fills and Embankments – Soil Strain Gauges......................................................................5
2.4 CABLE INSTALLATION AND SPLICING ..................................................................................................................6
2.5 INITIAL READINGS ...............................................................................................................................................6
2.6 ELECTRICAL NOISE..............................................................................................................................................6
2.7 LIGHTNING PROTECTION .....................................................................................................................................7
3. TAKING READINGS.............................................................................................................................................8
3.1 GK-404 READOUT BOX.......................................................................................................................................8
3.1.1 Operating the GK-404 ................................................................................................................................8
3.2 GK-405 READOUT BOX.......................................................................................................................................9
3.2.1 Connecting Sensors with 10-pin Bulkhead Connectors Attached ...............................................................9
3.2.2 Connecting Sensors with Bare Leads..........................................................................................................9
3.2.3 Operating the GK-405 ................................................................................................................................9
3.3 GK-403 READOUT BOX (OBSOLETE MODEL)....................................................................................................10
3.3.1 Connecting Sensors with 10-pin Bulkhead Connectors Attached .............................................................10
3.3.2 Connecting Sensors with Bare Leads........................................................................................................10
3.3.3 Operating the GK-403 ..............................................................................................................................10
3.4 MEASURING TEMPERATURES.............................................................................................................................10
4. DATA REDUCTION ............................................................................................................................................11
4.1 DEFORMATION CALCULATION...........................................................................................................................11
4.2 TEMPERATURE CORRECTION .............................................................................................................................13
4.3ENVIRONMENTAL FACTORS ...............................................................................................................................14
5. TROUBLESHOOTING........................................................................................................................................15
APPENDIX A. SPECIFICATIONS.........................................................................................................................17
A.1 MODEL 4430 DEFORMATION METER ................................................................................................................17
A.2 THERMISTOR (SEE APPENDIX BALSO) ..............................................................................................................17
APPENDIX B. THERMISTOR TEMPERATURE DERIVATION.....................................................................18

FIGURES
FIGURE 1-MODEL 4430 DEFORMATION METER ........................................................................................................... 1
FIGURE 2-4435 PRINT .................................................................................................................................................. 2
FIGURE 3-O-RING BULLET ........................................................................................................................................... 3
FIGURE 4-BOREHOLE INSTALLATION ........................................................................................................................... 4
FIGURE 5-INSTALLATION ALONG CREST OF DAM ........................................................................................................ 5
FIGURE 6-BOREHOLE INSTALLATION IN EMBANKMENT............................................................................................... 5
FIGURE 7-LIGHTNING PROTECTION SCHEME ............................................................................................................... 7
FIGURE 8-LEMO CONNECTOR TO GK-404 ................................................................................................................... 8
FIGURE 9-LIVE READINGS –RAW READINGS............................................................................................................... 9
FIGURE 10 -ATYPICAL CALIBRATION SHEET ..............................................................................................................12
TABLES
TABLE 1-ENGINEERING UNITS CONVERSION MULTIPLIERS ........................................................................................11
TABLE 2-THERMAL COEFFICIENT CALCULATION CONSTANTS ...................................................................................13
TABLE 3-SAMPLE RESISTANCE ...................................................................................................................................16
TABLE 4-RESISTANCE WORK SHEET...........................................................................................................................16
TABLE 5-MODEL 4430 SPECIFICATIONS......................................................................................................................17
TABLE 6-THERMISTOR RESISTANCE VERSUS TEMPERATURE ......................................................................................18
EQUATIONS
EQUATION 1-DIGITS CALCULATION............................................................................................................................11
EQUATION 2-DEFORMATION CALCULATION ...............................................................................................................11
EQUATION 3-THERMALLY CORRECTED DEFORMATION CALCULATION ......................................................................13
EQUATION 4-THERMAL COEFFICIENT CALCULATION .................................................................................................13
EQUATION 5-GAUGE LENGTH CORRECTION ...............................................................................................................14
EQUATION 6-RESISTANCE TO TEMPERATURE .............................................................................................................18

1
1. INTRODUCTION
1.1 Theory of Operation
The Geokon Model 4430 Vibrating Wire Deformation Meter is designed to measure axial
deformations in boreholes in rock, concrete or soil. It can also be embedded in soils in
embankments such as earth dams and highway fills. The units can be installed in series providing
incremental deformation measurements over any length. Base lengths of the gauge can vary from
a minimum of one meter to over 25 meters.
The basic sensing element is a vibrating wire strain gauge in series with a precision music wire
spring that is coupled to a movable shaft. As the shaft moves in or out of the sensor body, the
tension changes in the spring as well as the vibrating wire element. This change in tension is
directly proportional to the amount of extension and, through calibration, a calibration factor that
relates the frequency of vibration to the amount of extension is determined. The unit is stress
relieved after manufacture providing for excellent stability over long periods of time.
The gauge sensor is attached to a flange at one end and by a connecting rod of some length to a
flange at the other end. The sensor and the rod are covered by a plastic (PVC) tube which holds
the end flanges apart at a predetermined distance (gauge length), and insures that the rod is free
to move. As the flanges move apart, the movement is conveyed by the connecting rod to the
sensor and measured by the readout system. Different combinations of gauge length and sensor
range provide for optimum sensitivity. For maximum strain resolution, a long base gauge with a
short range transducer will give best results. For maximum deformation: short base length,
longer transducer range. The flexibility of the system allows the user to choose the most useful
combination of range and sensitivity according to predicted movements.
Nominal Gage Length
(1m, 39")
End Flange
Swagelok Fitting
Instrument Cable
End Flange
Electromagnetic Coils Thermistor
(4 conductor, 22 AWG)
PVC Outer Tube
Transducer Shaft HousingAlignment Pin
Alignment Slot
Extension Rod Transducer Shaft
Figure 1 - Model 4430 Deformation Meter
Readouts available from Geokon, used in conjunction with the Vibrating Wire Deformation
Meter, will provide the necessary voltage pulses to pluck the wire and convert the measured
frequencies to display the reading.

2
2. INSTALLATION
2.1 Preliminary Tests
Upon receipt of the instrument, the gauge should be checked for proper operation (including the
thermistor). In position "B" the gauge will read between 2000 and 8000 digits (see Section 3 for
readout instructions). When pulling slightly on the end flanges (items number three and four in
Figure 2), the reading should increase.
Checks of electrical continuity can also be made using an ohmmeter. Resistance between the
gauge leads should be approximately 180Ω, ±10Ω. Remember to add cable resistance when
checking. (22 AWG stranded copper leads have a resistance of approximately 14.7Ωper 1000
feet or 48.5Ωper kilometer. Multiply these factors by two to account for both directions.)
Resistance between the green and white conductors should be approximately 3000 ohms at 25 °C
(see Table 6 in Appendix B for other temperatures), and between any conductor and the shield
should exceed two megohms.
2.2 Sensor assembly
Figure 2 - 4435 Print

3
Complete the following:
(Item numbers referenced in the following steps are detailed in Figure 2.)
1) Remove the 1.315” shipping tube (Item 6) from the back of the transducer and discard. At
this point, the shipping spacer, or shipping pin, can be removed and the push rod can be
gently retracted back into the transducer. Perform preliminary tests on the sensors to verify
proper operation (Section 2.1).
2) Install a length of flush-coupled connecting rod (Item 12) into the threaded rod of the
transducer. Use a thread locker if available. Caution: When threading the connecting rod into
the push rod of the transducer, ensure the pin of the pushrod is fully engauged in the slot of
the transducer tube to prevent rotation of internal components.
3) Slide the slip joint (Item 5) over the connecting rod and transducer until the end aligns with
the paint mark located on the flange to slip joint tube (Item 8). Tighten the nylon set screws
(Item 16) to maintain this position.
4) Spacers (Item 2) should be installed along the connecting rod at 3' (one meter) intervals to
prevent the rod from flexing in the tube. This is done by locating the spacer in its
approximate location and wrapping tape around the connecting rod on both sides of the
spacer using the provided electrical tape (Item 13).
5) Install the coupling to slip joint tube (Item 9) into the slip joint until the painted mark aligns
with the other side of the slip joint and tighten the nylon set screws (Item 16). Note:
Depending on the gauge length, this tube may couple directly to the shaft end flange (Item 4).
6) For longer gauge lengths, couplings and standard pipes are provided. Use PVC cement to
affix a coupling (Item 15) to the slip joint to coupling tube. On the other side of the coupling,
cement a length of standard pipe (Item 11). Continue to add couplings, tubes, spacers, and
connecting rod until there is only the shaft end flange to connect.
7) Attach the provided o-ring bullet (Item 7) to the final length of connecting rod. This will
allow the shaft end flange to be slid over the connecting rod without damaging the internal o-
rings. PVC cement the shaft end flange to coupling tube (Item 10) to the final coupling. The
o-ring bullet can now be removed and used with other assemblies.
Figure 3 - O-ring Bullet
8) At this point, the gauge length should be established. If minor adjustments are needed, the
nylon set screws in the slip joint can be loosened and either end adjusted to the proper
distance. Note: The assembly should only be adjusted by half the range of the sensor in either
direction from the painted mark.

4
9) To set the range of the transducer, take the end of the connecting rod (Item 12) protruding
out the back of the flange and pull it to the desired percentage of the range, either by
measuring the distance the rod was pulled, or by recording the reading of the sensor while
pulling on the connecting rod (preferred method). Make sure not to overextend the rod or
rotate it beyond 180 degrees as this may damage the sensor. Tighten the setscrews (Item 17)
in the rod end flange to lock the sensor's position in place. Any excess rod protruding out of
the back can be sawed off at this point, if needed.
10) Install the assembly, and then loosen the nylon setscrews. Take baseline zero readings for
comparison.
2.3 Deformation Meter Installation
2.3.1 Installation in Boreholes
The primary use of the Model 4430 is for the measurement of axial strains or
deformations in boreholes. The most common method of installation is by grouting.
Horizontal holes should be inclined slightly downward to make for easy grouting and to
avoid air pockets. Vertical up holes require special grouting apparatus and snap ring or
hydraulic anchors on the gauge to hold it in place while grouting the hole.
Horizontal and vertical down holes are instrumented as follows:
Drill the borehole at least 0.5 meters (≈two feet) beyond the location of the deepest
flange. The borehole must be a minimum of 60 mm (2.25") in diameter. Fill the hole with
grout mixture of one part Portland cement to one to two parts water by volume. An
expansive mix is helpful particularly in horizontal holes. Lower or push the sensor(s)
down the hole to the proper location as noted by a mark on the cable. If more than one
sensor is to be placed in a hole, be sure to maintain the position of the lower sensor while
installing shallower ones.
Grout
Instrument Cable
Deformation Meter
Fault
Borehole
Figure 4 - Borehole Installation
For situations such as soft ground or when the hole is cased and casing must be
withdrawn, it may be advisable to use a sensor with a hydraulic anchor for permanent
positioning. This should be discussed with the application engineers at the factory.