In-Situ Win-Situ 2000 Operators Manual - Manual (Page 23)

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SECTION 5: PRESSURE PARAMETER SETUP
• Level - Surface: Commonly used for
surface water elevations. Data file
readings are “positive up.” Increasing
water levels will result in increasing
readings. Decreasing water levels
correspond to decreasing readings.
• Level - Top Of Casing: Commonly
used for drawdown in groundwater
wells. This mode is “positive down.”
Decreasing water levels correspond to
increasing readings, because the water
level is getting further from the top of
the well casing. Increasing water levels
result in decreasing readings.
Level/Depth Conversion Information
The conversion from pressure in pounds per square inch (psi) to depth
or level in meters or feet requires several conversion factors. Pressure
in the English unit psi is converted to the SI unit Pascal (Pa).
Conversion from Pascals to meters or feet requires two additional
values:
• Liquid Density. Pure groundwater at 20°C has a density of 0.998 g/
cm 3 . Refer to the Appendix for a temperature/density table and a
method for experimentally determining liquid density if the working
fluid is not pure water.
• 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.
Earlier versions of Win-Situ before Win-Situ 2000 used a dimensionless
specific gravity value to convert from pressure to feet or meters of fluid.
A specific gravity of 1.0 is adequate for many groundwater applications.
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.