Users’ Manual
ESM-40S High sensitivity settlement monitoring system
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2.5 ESM-40S/3 Moisture trap
A moisture trap with desiccant and hydrophobic filter is used to terminate the vent line. It helps in
maintaining the barometric pressure in the settlement monitoring system. When air pressure (barometric
pressure) changes, the fluctuations are transmitted to the sensor through air vent tube. This results in
cancelling out the effect of barometric pressure on the sensor. Desiccant and hydrophobic filter ensure that
the air inside the moisture trap is dry. This prevents any moisture to enter into the vent line.
The moisture trap unit is mounted near the reservoir, preferably above the top level of the reservoir. It has
two quick connectors – to connect to the vent line from the reference sensor and another vent tube from
the reservoir.
2.6 ESM-40S/4 Fluid and air vent tubes
8 mm od tubes are used as fluid and air vent tubes. Air vent tube is required to compensate the barometric
pressure inside the sensor. It ensures that the air pressure both inside and outside the sensor are same
so that any change in atmospheric pressure does not affect the reading of the transducer.
2.7 ESM-40S/5 Pressure gage and valve assembly
Pressure gage and valve assembly consists of an air pressure gage with regulator to control the pressure.
This is required when the water is being filled in the system using pressure vessel and compressor/pump.
It also consist of suitable valves to maintain the pressure.
This system is very important to control the fluid pressure within limit (0.1 bar). The pressure transducer
used in the settlement sensor is of very low range.
Even a slightly higher pressure than 0.1 bar may damage
the sensor.
Figure 2-5 Gage and valve assembly
