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"H 2 O
psi
1
.036127 .43275
psi
"H 2 O
27.730
1
'H 2 O
2.3108
.08333
mm H 2 0 704.32
25.399 304.788
.70432 .025399 .304788
m H 2 0
2.036
.073552 .882624 .0028959 2.8959
"HG
mm HG 51.706
1.8683 22.4196
atm
.06805 .0024583 .0294996 .0000968
mbar
68.947
2.4908 29.8896
bar
.068947 .0024908 .0298896 .0000981 .098068 .033863 .001333 1.0132
6.8947
.24908 2.98896 .0098068 9.8068
kPa
MPa
.006895 .000249 .002988 .00000981 .009807 .003386 .000133 .101320 .0001
Note: Due to changes in specific gravity with temperature, the factors for mercury and water in
Table 3 are approximations.
D.2 Temperature Correction
Careful selection of materials is made in constructing the vibrating wire piezometer to minimize
thermal effects; however, most units still have a slight temperature coefficient. Consult the
supplied calibration report to obtain the coefficient for a given piezometer.
Since piezometers are normally installed in a tranquil and constant temperature environment,
corrections are not normally required. If however, that is not the case for a selected installation,
corrections can be made using the internal thermistor for temperature measurement.
Temperature correction equation is as follows:
(Current Temperature - Initial Zero Temperature) × Thermal Factor
The calculated correction would then be added to the Pressure calculated using Equation 10. (If
the engineering units were converted, remember to apply the same conversion to the calculated
temperature correction!) For example, assume the initial temperature was 22° C, the current
temperature is 15° C, and the thermal coefficient is −.01879 PSI per °C rise. The temperature
correction is 0.13 PSI. Adding this to the calculated pressure in the beginning of this appendix
results in a temperature corrected pressure of 19.98 PSI.
'H 2 O
mm H 2 0 m H 2 0
.0014223 1.4223
12
.039372
39.372
1
.003281
3.281
1
1000
.001
1
.073558
73.558
.0968
.098068
98.068
Table 3 - Engineering Units Multiplication Factors
Temperature Correction =
P
= (T
T
Equation 11 - Temperature Correction
"HG mm HG
atm
.49116 .019337 14.696 .014503 14.5039 .14503
13.596
.53525 406.78 .40147
1.133
.044604 33.8983 .033456 33.4558
345.32
13.595 10332 10.197
.34532 .013595 10.332 .010197 10.197
1
.03937 29.920 .029529 29.529
25.4
1
760
.75008
.03342 .0013158
1
.0009869 .98692 .009869
33.863
1.3332 1013.2
3.3863
.13332 101.320
Or
-T
) x K
1
0
mbar
bar
kPa
401.47
4.0147
.3346
10197
101.97
.10197
.2953
750.08
7.5008
1
1000
10
.001
1
.01
.1
100
1
.1
.001
MPa
145.03
4016.1
334.6
101970
101.97
295.3
7500.8
9.869
10000
10
1000
1
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