RST Instruments VW2100-DP - Second Order Polynomial Pressure Equation

VW2100 Vibrating Wire Piezometer
Instruction Manual
ELM0005P
RST Instruments Ltd.
Page 12
S
i
= 1003.1 mbar
S = 995 mbar
P = [(0.11594) x (8776 - 7200)] - [(-0.03413) x (22.9 - 5.0)] + [0.1 x (1003.1 - 995)]
= [182.72] - [-0.61] + [0.81]
= 184.14 kPa
NOTE: BAROMETRIC COMPENSATION IS NOT REQUIRED WITH VENTED AND
DIFFERENTIAL PRESSURE TRANSDUCERS.
4.4.2 Second Order Polynomial Equation
𝑃 = 𝐴(𝐿)
2
+ 𝐵
(
𝐿
)
+ 𝐶 − 𝑇
𝐾
(
𝑇
0
− 𝑇
)
+ 𝐹(𝑆
0
− 𝑆)
EQUATION 2 SECOND ORDER POLYNOMIAL EQUATION
Where:
P = Corrected Pressure in kPa
A = Polynomial Gauge Factor A in kPa/B-Unit
2
(Second Order Polynomial
Expression derived from the VW Piezometer Calibration data, for each
individual sensor)
B = Polynomial Gauge Factor B in kPa/B-Unit (Second Order Polynomial
Expression derived from the VW Piezometer Calibration data, for each
individual sensor)
C = Polynomial Gauge Factor C kPa (Second Order Polynomial Expression
derived from the VW Piezometer Calibration data, for each individual
sensor)
NOTE: POLYNOMIAL GAUGE FACTOR C MUST BE CALCULATED USING THE SITE
ZERO READINGS, AS PER THE EQUATION BELOW.
C = - [A(L
0
)
2
+ B(L
0
)]
L
0
, L = Initial and Current B-Unit reading (Frequency
2
x 10
-3
)
T
K
= Temperature Correction Factor in kPa/ºC (From the VW Piezometer
Calibration Record sheet in each individual sensor)
T
0
, T = Initial and current temperature readings in (ºC)
F = Barometric Pressure Constant = 0.1 kPa/mbar
S
0
, S = Initial and Current Barometric pressure readings in mbar