3
3. PRELIMINARY TESTS
Upon receipt of the piezometer the zero reading should be checked and noted. A Model 4700
VW Temperature Sensor is included inside the body of the sensor for the measurement of
temperature. (See Section 5 for readout instructions.)
Calibration data are supplied with each gage and zero readings at six different temperatures and
barometric pressure is included. Zero readings at the site should coincide with the calibration
zero readings within ±50 digits after barometric and temperature corrections are made. The
factory elevation is +580 ft. Before March 21, 1995 factory barometric pressure readings were
corrected to sea level; readings after this date represent absolute pressure. (Barometric pressure
changes with elevation at a rate of
≈
1/2 psi per 1,000 ft.) See Section 6 for sample calibration
reports.
4. INSTALLATION IN BOREHOLES
Before installing make sure both pressure and temperature sensors are working and record initial
readings with a portable readout box (GK-403 or GK 404).
Push the sensor into the borehole by whatever means are chosen. This may include attachment to
grout pipes, special installation rods or other apparatuses being inserted into the borehole at the
same time.
5. TAKING READINGS
The 4500HT is usually connected to a datalogger, but for initial set up it is often more
convenient to use a portable readout box. When the 4500HT piezometer is connected to a
datalogger the pluck voltage must be set to 12 volts.
5.1 GK-404 Readout Box
The Model GK-404 Vibrating Wire Readout is a portable, low-power, handheld unit that is
capable of running for more than 20 hours continuously on two AA batteries. It is designed for
the readout of all Geokon vibrating wire gages and transducers, and is capable of displaying the
reading in either digits, frequency (Hz), period (µs), or microstrain (µε).
5.1.1 Operating the GK-404
Before use, attach the flying leads to the GK-404 by aligning the red circle on the silver
Lemo connector of the flying leads with the red line on the top of the GK-404 (Figure 3).
Insert the Lemo connector into the GK-404 until it locks into place.
Содержание 4500HT
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Страница 15: ...9 Figure 5 A Typical Model 4700 VW Temperature Sensor Calibration Report ...
Страница 16: ...10 Figure 6 Typical Calibration Report at 25 C ...
Страница 17: ...11 Figure 7 Typical Calibration Report at 100 C ...
Страница 18: ...12 Figure 8 Typical Calibration Report at 150 C ...
Страница 19: ...13 Figure 9 Typical Calibration Report at 200 C ...
Страница 20: ...14 Figure 10 Typical Calibration Report at 250 C ...