Geokon 4580, Instruction Manual

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2.2.2 Piezometer
When used as a piezometer or weir monitor, the vented version is usually chosen. In this
case, care must be taken to be sure the entire pressure cavity surrounding the capsule is
filled with water. A hole with a seal screw is provided on the body of the transducer to
allow water to flow through the pressure chamber. Flush water through the body of the
sensor with the water entering at the tip of the sensor and exiting through the seal screw.
Agitate the body of the sensor until no bubbles are seen exiting the seal screw port. The
screw should be replaced with the transducers held under water to prevent air from
reentering the sensor. (Air trapped in the chamber can cause inaccurate and/or unstable
pressure readings in changing temperature environments.)
The vented versions incorporate a moisture trap on the end of the vent line. Desiccant
inside the moisture trap prevents moisture from entering the inside of the sensor capsule.
The vent trap screw must be removed during the measurement period to equalize the
changes in barometric pressure both inside and outside the pressure capsule. (When the
desiccant turns from blue to pink it should be replaced.)
Transducer Cable
Vent Line
Moisture Trap
Cap
Slotted Pipe
Ground Surface
Weir
Transfer Pipe
Model 4580 Pressure Transducer
Water Level
Figure 3 - Model 4580 Weir Monitor Installation