In-Situ Win-Situ 4 / Pocket-Situ 4 Operators Manual - Manual (Page 94)

94
rev. 003 11/04
DETERMINING DENSITY
The density of water in a well can be determined using an accurate tape
measure and a pressure transducer. A change in pressure is recorded
between two points as the transducer is lowered into the water and the
corresponding change in depth is recorded using the measuring tape.
Density is then calculated using a simple formula. This method is valid if
the pressure and depth measurements are accurate and the water within
the well is homogeneous throughout the entire depth of the well.
Note: Density can also be measured using a hydrometer if it is possible to
withdraw a water sample from the well. We recommend an accuracy of
±0.0005
Procedure
There are two possible methods for measuring the change in water depth.
Choose the method that is the most convenient and accurate.
• Attach the tape measure to the transducer cable using an adhesive
(e.g., duct tape). The tape measure can be attached to the transducer
itself or to a segment of the cable that will be adjacent to the top of the
well casing. Read the cable positions directly from the measuring tape.
The measuring device must have a resolution of at least 1 mm or 1/16
in.
• Alternatively, mark the positions of the cable with a felt tip pen. The
distance between marks is then determined with a tape measure after
the corresponding cable segment is removed from the well.
1. Lower the transducer into the well until it is submerged under about
one meter of water.
2. Secure the transducer at a fixed depth using the cable at the top of the
well casing. Wait an hour or so for the system to equilibrate.
TIP: If using a
tape measure
calibrated in feet,
1 ft = 0.3048 m (exactly).
APPENDIX A: LIQUID DENSITY