E10160-200722
FOP
Page 13
3
INSTALLATION
Fiber optic piezometers can be installed in various ways to suit each individual application.
Specific guidelines for the installation of piezometers have been set for piezometer
installation by various agencies and specialists. A list of references is given in appendix.
The following instructions summarize the generally accepted practice for:
filter saturation,
initial reading after installation
cable identification,
piezometers installed in clay fill, granular material or boreholes,
piezometers driven into soft soil,
cable routing.
3.1 FILTER SATURATION FOR FOP PIEZOMETERS
Two types of filters are available; high air entry ceramic or low air entry sintered stainless
steel filters. Saturation of the filter:
reduces the possibility of filter clogging,
decreases response time,
ensures hydraulic continuity between the pore water and the piezometer diaphragm
in unsaturated soils.
Low air entry sintered stainless steel filters
The filter on the FOP piezometer body is removed by holding the piezometer in one hand
and pulling and twisting the filter housing with the other hand.
Saturate the filter by placing it in a receptacle of clean water for at least 15 minutes.
Immerse the piezometer housing with the filter removed in a water bath. With the diaphragm
end pointing upwards and submerged, reassemble the filter. Tap piezometer housing lightly
to remove any air bubbles present. As soon as the filter is saturated, it must stay
submerged until ready to install.
High air entry ceramic filters
The ceramic filter is delivered cased in a bottle and pre-saturated in water. If the ceramic
filter is not pre-saturated, install the filter in a receptacle of clean water and boil the porous
ceramic filter for a minimum of two-hour period.
Final installation must be carried out under water to avoid any air intrusion.
Connect the piezometer to a readout unit.
Put the piezometer upside-down in a container filled with clean water. The
piezometer tip should be up and completely submerged.