Geosense VW PIEZOMETERS, Инструкция по эксплуатации

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35
Version 1.4 May 09
Linear Calculation
This is the most simple calculation to convert ‘raw’ data to engineering units. It can
be easily carried out using a simple calculator. It assumes that the reading is in
Linear Digits ( Hz
2
/1000 ). Where this is not the case, the reading should be
converted to these units prior to application of the calibration factors. For most
applications this equation is perfectly adequate and is carried out as follows:
Pressure ( psi ) =
Linear Factor for psi (k) x ( Current Reading - Base Reading )
Polynomial Calculation
This calculation is slightly more precise, as it accommodates some of the slight
deviation of the data from a straight line. However, in its standard form it does not
easily accommodate site recorded base reading or environmental changes that may
affect the zero ( such as altitude ).
Pressure ( psi ) =
[ Factor A for psi x (Reading)
2
] + [ Factor B for psi x Reading]
+ Factor C for psi
Where the Pressure is required in an alternative format, mH
2
O for example, a simple
conversion using standard conversion factors can be applied to each factor or at the
end of the equation. (1 psi = 0.7031 mH
2
O for example).
An instrument calibration sheet similar to the example in the appendix of this manual
includes the following information:
Model
This refers to the Geosense or RST model number.
Serial Number This is a unique sensor identification number that can be found
on the cable just behind the piezometer body and, for long
cables, at the end of the cable.
Works ID Unique works batch and range code
Cal Date Date the calibration was performed
Baro Barometric Pressure at the time of calibration
Temp
o
C Temperature at which the piezometer was calibrated
DPI No. Serial number of the Digital Pressure Indicator used in
conjunction with the pressure generator
Readout No. Serial Number of the readout used to display the transducer
output
R/O Cal Date The date on which the Readout was calibrated to a traceable
standard
Applied Pressure Pressure applied to the transducer as part of the calibration
cycle in both psi and kPa
Readings [digit] Readings from the transducer as pressure is applied and as
pressure is reduced, in steps. The average is calculated.
Calculated Pressure Calculation of the applied pressure using the calculated Linear
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