Campbell Scientific PST3/PST8 Pump and Slug Test System - Manual (Page 22)

4-1
SECTION 4. TECHNICAL DETAILS - HARDWARE
4.1 STORAGE MODULE
An optional SM192 or SM716 storage module
can be used to collect data from the PST or to
provide additional memory capacity. A bracket
is available (PST-BKT) for mounting the storage
module to the PST.
To collect data, simply plug the storage module
into the connector for the CR10KD
keyboard/display. An SC90 line monitor can be
used to monitor when the data collection is
complete.
The PST will not transfer any data to the
storage module during the first 20 minutes of a
Delta test, or the first 20 seconds of a
logarithmic test. All data will be transferred at
the end of a test (when recording is turned off).
To avoid possible data loss, wait at least 60
seconds after ending a test before changing
setup information in the *4 table.
NOTE: Do not turn the power off until you
have retrieved data from the Storage
Module. Otherwise, automated data
retrieval using PCPST will not be possible.
4.2 PRESSURE TRANSDUCERS
4.2.1 FACTORY CALIBRATION
Table 4.2-1 is an example of a calibration sheet
furnished with a Keller PSI Series 169/173
pressure transducer. The column labelled
"BFSL" is a best fit straight line calculated using
factory test data for this sensor. Please note
that each calibration is unique. Your data will
be different.
To obtain the multiplier in feet for each sensor:
M = (full scale pressure in psi) x (2.31 ft/psi)
(BFSL value at full scale - BFSL value at 0.0 psi)
The offset is set in the field. See Section 3.2.
4.2.2 TWO-POINT CALIBRATION
A two-point or multi-point calibration can be
calculated by using an initial multiplier of 1 and
offset of 0.0. Scan the sensors by setting the
scan switch to the ON position. Use *6 Mode to
monitor the appropriate input location. Record
on a sheet of paper the observed level and the
corresponding voltage for two or more points.
For a two point calibration:
Multiplier (m) = (depth 2 - depth 1)/
(voltage 2 - voltage 1).
Offset (b) = depth 1 - m X voltage 1.
For a multi-point calibration, use the desired
method to fit a straight line to your data.
4.2.3 OVERRANGE
The PST measures the output of the transducer
on a 0 to +25 millivolt input range. If the psi
range of the transducer is exceeded, the output
voltage of the transducer potentially could
exceed 25 mV. An overrange occurs if the
sensor outputs more than 25 mV. A -6999 in
the data file represents an over-range. In the
monitor mode of PC208 program GraphTerm,
an overrange is represented by a -99999.
Two excitation codes can be specified in *4
mode to match the full scale output of the
transducer to the +25 mV input range. Select
the default of "0" for transducers in the range of
5 to 20 psi. If the transducer is 30 psi or
greater, the corresponding excitation code
should be set to "1" in *4 mode.
NOTE: Unexpected overrange readings
may indicate a sensor problem, such as
poor connection.
4.3 LOGARITHMIC SAMPLING
INTERVALS
Logarithmic sampling is based on the execution
interval set in *4 mode. The default interval is
0.25 seconds which results in the following
intervals:
Points per
Elapsed Time Interval Interval
0 - 20 sec. 0.25 sec. 80
20 - 120 sec. 5 sec. 20
2 - 10 min. 30 sec. 16
10 - 100 min. 2 min. 45
100 - 1000 min. 10 min. 90
1000 min. plus 60 min.
# of seconds in *4 location 13 (PST3)
or 28 (PST8)