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18
6. DATA REDUCTION
6.1 Pressure Calculation
The pressure measured by the piezometer is determined by the following linear equation:
Pressure = (Current Reading - Initial Reading) × Gage Factor
Where;
P is the applied pressure in kPa or psi.
R
is the initial output in millivolts, volts, or milliamps.
0
R
is the current output in millivolts, volts, or milliamps.
1
G is the gage factor, as shown on the supplied calibration report.
For Example;
Model 3400-1-100KPA Input Voltage = 12.0 volts
R
= -0.0.006 mV
0
R
= 18.0 mV
1
G = 1.004 kPa/mV
P = 1.004 (18.0 – (– 0.006)) x 10/12= 15 kPa
The Initial Reading (R
4.1. To convert the output to other engineering units, multiply the Calibration Factor by the
conversion multiplier listed in Table 2.
From →
To
↓
"H 2 O
psi
psi
1
.036127 .43275 .0014223 1.4223 .49116 .019337 14.696 .014503 14.5039 .14503 145.03
"H 2 O
27.730
1
'H 2 O
2.3108 .08333
mm H 2 0 704.32 25.399 304.788
m H 2 0 .70432 .025399 .304788
"HG
2.036 .073552 .882624 .0028959 2.8959
mm HG 51.706 1.8683 22.4196 .073558 73.558
.06805 .002458 .029499 .0000968 .0968 .03342 .001315
atm
mbar
68.947 2.4908 29.8896 .098068 98.068 33.863 1.3332 1013.2
bar
.068947 .002490 .029889 .0000981 .098068 .033863 .001333 1.0132
6.8947 .24908 2.98896 .0098068 9.8068 3.3863 .13332 101.320
kPa
.006895 .000249 .002988 .0000098 .009807 .003386 .000133 .101320 .0001
MPa
P = (R
Equation 1 - Convert Digits to Pressure
) is normally obtained at the time of installation, as described in Section
0
'H 2 O mm H 2 0 m H 2 0
12
.039372 39.372 13.596 .53525 406.78 .40147 401.47 4.0147 4016.1
1
.003281 3.281
1
1000
.001
1
Table 2 - Engineering Units Multiplication Factors
Or
– R
)×G
1
0
"HG mm HG
atm
1.133 .044604 33.8983 .033456 33.4558 .3346
345.32 13.595 10332 10.197 10197 101.97 101970
.34532 .013595 10.332 .010197 10.197 .10197 101.97
1
.03937 29.920 .029529 29.529 .2953
25.4
1
760
1
mbar
bar
kPa
.75008 750.08 7.5008 7500.8
.000986 .98692 .009869 9.869
1
1000
10
.001
1
.01
.1
100
1
.1
.001
MPa
334.6
295.3
10000
10
1000
1
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