E10160-200722
FOP
Page 19
Use a combination of horizontal and vertical snaking at transition zones.
The trench dimensions should be 25 cm wider than the laid out width of the cable. The
trench should be a minimum of 60 cm deep. A 12 cm bedding layer of minus 0.8 mm sand
is placed along the trench bottom. As required, bentonite must be added to the sand to form
impervious sections or plugs.
The cable is then covered with one 15cm lift of minus 0.8 mm material.
Backfill the trench with selected material completely and compact the selected material with
light hand operated machines.
During the cable routing, read the instruments at regular intervals to ensure continued
proper functioning.
4
Relation between gauge factor and calibration factor
The Gauge Factor (GF) is specific for each pressure sensor and is written on the fiber
optic cable near the connector. It gives the relationship between the deflection of the
diaphragm and the applied pressure. The Gauge Factor is a 7-digit number, for example
6025192. The structure of the Gauge Factor is given below:
6 0 2 5 1 9 2
6 X Y Z Z Z Z
The following table presents the meaning of each digit contained in the Gauge Factor.
6
This first digit is the same for every pressure sensor;
this is an identifier indicating to the readout unit that it is
a pressure sensor.
X
This digit is a sensor number. It is used if more than one
sensor have the same calibration factor; generally, this
value equals zero.
Y
This digit is an exponent used in the conversion
calculations from cavity distance variation (nm) to
pressure unit (psi).