49
TROLL
9500
Operator’s Manual
0095110 rev. 007 01/09
Liquid Density
4HECONVERSIONFROM03)UNITSTOMETERSORFEETOFmUIDREQUIRES
several conversion factors. One of these is the density (
R
) of the
AQUEOUSSOLUTIONBEINGMONITORED0UREGROUNDWATERAT½#HASA
density of 0.998 grams per cubic centimeter (g/cm
3
).
Use the values in the table for density if you do not otherwise know
it. However, since these data assume pure water, there is no ac-
commodation for other variables (such as salinity) that can affect
your actual water conditions. Alternatively, you could compute the
mUIDDENSITYUSINGTHEPROCEDUREGIVENINTHE!PPENDIX
Fluid density by temperature
Temp.
Density Temp.
Density Temp.
Density
½#
GCM
3
½#
GCM
3
½#
GCM
3
)
1 0.999900 11 0.999605 21 0.997992
2 0.999941 12 0.999498 22 0.997770
3 0.999965 13 0.999377 23 0.997538
4 0.999973 14 0.999244 24 0.997296
5 0.999965 15 0.999099 25 0.997044
6 0.999941 16 0.998943 26 0.996783
7 0.999902 17 0.998774 27 0.996512
8 0.999849 18 0.998595 28 0.996232
9 0.999781 19 0.998405 29 0.995944
10 0.999700 20 0.998203 30 0.995646
3. CONVERTING PRESSURE TO DEPTH OR LEVEL
The conversion from pressure in pounds per square inch (psi) to
depth or level in meters or feet requires some knowledge of the
PROPERTIESOFTHEmUIDBEINGMONITOREDANDOPTIONALLYOFTHEDEVICES
location on the earth’s surface.
Conversion Using Specific Gravity
0RESSUREMAYBEADEQUATELYCONVERTEDTOFEETORMETERSOFmUIDUSING
a dimensionless specific gravity value. A specific gravity of 1.0 (char-
ACTERISTICOFPUREWATERAT½# ISADEQUATEFORMANYGROUNDWATER
applications.
Conversion Using Density, Latitude, and Elevation
Pressure in the English unit psi is first converted to the SI unit Pascal
(Pa). Conversion from Pascals to meters or feet requires two ad-
ditional values:
s
Liquid Density.
0UREGROUNDWATERAT½#HASADENSITYOF
g/cm
3
. A table of density by temperature appears on this page. The
Appendix includes a method to experimentally determine liquid
DENSITYIFTHEWORKINGmUIDISNOTPUREWATER
s
Gravitational Acceleration.
The acceleration due to gravity that
an object experiences is location-specific. Given your latitude and
elevation, Win-Situ can calculate a value for gravitational accelera-
tion for your location.
TIP:
Either
specific gravity
or
density, latitude & elevation
may be used to convert from pressure (psi) to depth/level
(meters or feet ). A gain in accuracy may be realized by
selecting the density, latitude & elevation option.
4. LEVEL REFERENCE
If you selected a level display mode (Surface or Top of Casing), you
will be prompted to enter a level reference. This is a user-specified
starting point for level display modes, and can be any value you
choose. Here are some examples:
s 3URFACE)FYOUCALCULATETHEWATERLEVELABOVEMEANSEALEVEL
(MSL) and enter this as the Level Reference, then data will be
displayed as elevations above MSL.
s 4OPOF#ASING)FYOUMEASURETHEDISTANCETOTHEWATERSURFACE
(DTW) from the top of the well casing and enter this number as the
Level Reference, then data will be displayed as DTW values.
s !,EVEL2EFERENCEOFISEQUIVALENTTOhZEROINGvTHEPROBE$ATA
will be displayed as changes, either positive or negative, from the
starting water level.
Reference Time
The MP TROLL takes a “snapshot” of the sensor’s raw pressure read-
ing, then your Level Reference is substituted. You can specify that the
snapshot be taken now or when the test starts. The data file will show
the Reference (raw pressure) Reading and when it was taken.
s
Now:
the pressure is measured when you finish setting up the
pressure parameter, and the value is stored until the test starts. All
measurements taken during the test will be relative to the water
level at the time you finished the wizard.
s
Start of Test:
the Reference measurement will be taken at time
t=0. All measurements taken during the test will be relative to the
water level at the moment the test starts.
TIP:
After setting up the pressure channel with the desired
display options, select the units you want to see. Use Win-
Situ’s Options menu, or Pocket-Situ’s Setup button.
SECTION 7: MONITORING PRESSURE (WATER LEVEL)