Geokon 4580, Instruction Manual

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2.2.3 Pressure Transducer
The transducer has 1/4" NPT female thread on the front end allowing for connection to
various types of fittings. Both vented and unvented transducers are used in this version
and the choice depends upon the application and whether barometric changes must be
automatically eliminated from the readings.
The wrench flats on the transducer should be used when tightening fittings into the
transducer.
Prior to use, flush the transducer with water to remove all air from inside the sensor. This
can be done by removing the seal screw and pumping water through the sensor. Replace
the seal screw when bubbles no longer appear.
2.3 Splicing and Junction Boxes
Because the vibrating wire output signal is a frequency rather than a current or voltage,
variations in cable resistance have little effect on gauge readings. Therefore, splicing of cables
has no effect, and in some cases, can in fact be beneficial. For example, if multiple transducers
are installed in a borehole, and the distance from the borehole to the terminal box or datalogger is
great, a splice (or junction box) could be made to connect the individual cables to a single multi-
conductor cable. This multi-conductor cable would then be run to the readout station. For these
types of installations, it is recommended that the transducer be supplied with enough cable to
reach the installation depth, plus extra cable to pass through drilling equipment (rods, casing,
etc.).
Cable used for making splices should be a high-quality twisted pair type, with 100% shielding
and an integral shield drain wire.
When splicing, it is very important that the shield drain
wires be spliced together. Splice kits recommended by Geokon incorporate casts that are placed
around the splice and then filled with epoxy to waterproof the connections. When properly made,
this type of splice is equal or superior to the cable in strength and electrical properties. Contact
Geokon for splicing materials and additional cable splicing instructions.
Junction boxes and terminal boxes are available from Geokon for all types of applications. In
addition, portable readouts and dataloggers are also available. Contact Geokon for specific
application information.
2.4 Electrical Noise
Care should be exercised when installing instrument cables to keep them as far away as possible
from sources of electrical interference such as power lines, generators, motors, transformers, arc
welders, etc. Cables should never be buried or run alongside AC power lines as they will pick up
the noise from the power cable, which will likely cause unstable readings. Contact the factory
concerning filtering options available for use with the Geokon dataloggers and readouts.