RANGES
This pressure and temperature recording system is manufactured in three ranges: (a) 0 to 5 metres (b) 0 to 10 metres (c) 0 to 20 metres

MEASUREMENT RESOLUTION
(a) 0 to 5 metres : approx 1.5mm
(b) 0 to 10 metres: approx 3.0mm
(c) 0 to 20 metres: approx 6.0mm

TEMPERATURE RESOLUTION
The temperature sensor provides temperature readings with a resolution of 0.02 degrees centigrade.

RECORDER MEMORY
The Odyssey data recorder has 64k memory.

READINGS
The data recorder records 8190 dual sensor readings (temperature and pressure). The interval between readings can be set when the recorder is started at any interval between 20 seconds (4320 readings per day) and 8 hours (3 readings per day).

CALIBRATION
The PC software supplied with the recorder allows linearity correction of the sensor calibration using a polynomial mathematical program. This will generally give a linearity of approx +/-0.1% over the full scale range of the sensor. The PC software also allows complete elimination of the very slight temperature drift of the pressure sensor.

SIZE
The physical size of this system (data recorder and pressure/temperature sensor) is 39mm diameter and 160mm long.

VENT TUBE
To achieve maximum accuracy, all underwater pressure sensors must be vented to atmosphere to remove atmospheric pressure variations from the water height measurement. The data recorder uses a very tough nylon tubing to vent the sensor to atmospheric pressure. The top of the tube has a suspension and vent opening unit. This unit has provision for fitting a suspension line if the vent unit is to be suspended below ground level in groundwater level measurements.

BATTERIES
The data recorder includes two ½ AA Lithium cells spot welded together. The batteries can be purchased from Dataflow Systems.

APPLICATIONS

• Groundwater bores.
• Surface water measurements.

Dimensions                   Length 200mm, diameter 39mm

Weight                         350gm

Housing Material                                    PVC / Acetal

Operating Temperature Range   0 to 65 °C

Maximum Operating Depth (Submerged)            30m

Mounting Method            Suspended by wire attached to the top cap for bore applications or by a clamp to a fixed object in open water applications.

Method of Operation

The salinity of free water is measured by induction where the conductivity of the water alters the signal coupling between two wire coils embedded in the housing.  The lower 100mm of the recorder must be fully immersed for proper operation.  A temperature sensor inside the logger housing measures the water temperature at the same time as the conductivity. The logger must remain immersed in the water long enough for the temperature inside the logger to stabilise at the water temperature.

Power Supply               7.2V 1200mAH Lithium Battery Pack

                                    20mA peak current, 0.01mA idle current

Battery Life                  Better than 12 months with a 10 minute sample rate

                                    Better than 18 months with a 30 minute sample rate

                                    ** Not guaranteed.  Assumes new batteries.

Conductivity Ranges       Range 1          0 to 80 mSiemens cm^-1

                                       Range 2          0 to 40 mSiemens cm^-1

                                       Range 3          0 to 15 mSiemens cm^-1

                                                    Selected at time of manufacture.

                                                Ranges overlap slightly.

            Resolution                   Range 1 ⁺  0.1 mS cm^-1

                                                Range 2 ⁺  0.1 mS cm^-1

                                                                Range 3 ⁺  0.05 mS cm^-1

** displayed resolution can be changed by the user in the Odyssey Software Program **

Accuracy                     ⁺ 5% F.S.

                                    *Depends on calibration accuracy and whether linear or polynomial scaling is used *

Temperature Range               0 to 70 °C

            Resolution                 ⁺ 0.1 °C

            Accuracy                   ⁺ 1 °C     * depends on calibration accuracy *

Stabilisation Time            30 minutes for a step change in the immersed temperature

Clearances                               The recorder should be mounted at least 25mm clear of any metal objects and 25mm clear of the bottom of any bore or container to prevent erroneous readings.