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5.4 Vented Piezometers
Vented piezometers are designed to eliminate barometric effects. The space inside the transducer
is not hermetically sealed and evacuated; instead, it is connected via a tube (integral with the
cable) to the atmosphere. A chamber containing desiccant capsules is attached to the end of the
tube to prevent moisture from entering the transducer cavity. Vented piezometers require more
maintenance then unvented types, and there is always a danger that water can find its way into
the inside of the transducer and ruin it.
In order to keep the desiccant fresh during storage and transportation, the outer end of the
desiccant chamber is closed by means of a seal screw when shipped from the factory.
THIS
SEAL SCREW MUST BE REMOVED BEFORE THE PIEZOMETER IS PUT INTO
SERVICE!
The desiccant capsules are blue when fresh. They will gradually turn pink as they absorb
moisture. When they have turned light pink in color, they should be replaced. Contact Geokon
for replacement capsules.
5.5 Environmental Factors
Since the purpose of the piezometer installation is to monitor site conditions, factors that may
affect these conditions should always be observed and recorded. Seemingly minor effects may
have a real influence on the behavior of the structure being monitored, and may give an early
indication of potential problems. Some of these factors include, but are not limited to: blasting,
rainfall, tidal levels, traffic, temperature and barometric changes, weather conditions, changes in
personnel, nearby construction activities, excavation and fill level sequences, seasonal changes,
etc.
