Geokon 1300, Instruction Manual

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2
2. INSTALLATION
2.1. Preliminary Tests
Before assembly and installation of the extensometer the transducers should be checked for
proper operation. See Section 3 for readout instructions. In position "B" of the GK-401, GK-
403 and GK-404 Readouts the gage will read between 2000 and 2500. The transducer may need
to be slightly extended to get a reading. Pull on the Swagelok affixed to the transducer shaft to
do this (see Figure 1).
Checks of electrical continuity can also be made using an ohmmeter. Resistance between the
gage leads should be approximately 180

, ±10

. Remember to add cable resistance when
checking (22 AWG stranded copper leads are approximately 14.7

/1000' or 48.5

/km, multiply
by 2 for both directions). Between the green and white should be approximately 3000 ohms at
25° (see Table B-1), and between any conductor and the shield or the case of the sensor should
exceed 2 megohms.
Checks on the actuation of the anchor pistons must be done with care. The anchor must first be
positioned inside a piece of pipe or tubing with an inside diameter of approximately 50mm(2
inch), before the pistons are actuated by pneumatic pressure. If the pneumatic pressure is applied
to the pistons while the anchor is not inside a tube, the pistons will over-range and in the process
the O-ring seals will be damaged and the pistons will then be unable to hold pneumatic pressure
without leaking
2.2. Extensometer Installation
If the transducers check out the assembly can proceed.
An adequate area must be located for the assembly of the extensometer. Preferably it should be
as long as the extensometer, clear of debris and obstructions. When assembling the extensometer
in the field be especially careful to keep dirt out of the Swagelok fittings for the inflation lines.
1. Determine the anchor positions, i.e. the depth or position in the borehole for each anchor.
Starting with the bottom, or deepest, anchor calculate the distance between it and the
second anchor; this is the increment over which the measurement will be made. The
connecting rod must now be cut to the proper length to make up this increment. For the
standard 25 mm (1") transducer positioned at mid-range the length of the transducer
assembly is 492 mm (19.375"). This length must be deducted from the increment length
in order to make the correct rod length. For example, if the increment length is 3 meters
the rod length is 2.508 meters (3.0 - 0.492). Calculate the rod lengths for all anchor
positions and cut rods to length. Be careful when cutting the fiberglass rod that it does
not splinter. Use a file to deburr the edges.