HOBO U24 Conductivity Logger Manual
5
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Note for both methods:
If you record the meter calibration readings in measured electrical conductivity, you will need to
convert the readings to specific conductance at 25°C to enter them into the Conductivity Assistant. The formula for Specific
Conductance (C
s
) at 25°C is:
C
s
= Y
e
/ (1 - ((25-T) * a / 100))
Where: Y
e
= Measured Electrical Conductivity
a = 2.1 % / degrees C for seawater or Sodium Chloride solutions, or 1.8% / degree C for Potassium Chloride
solutions; the value used for (a) must match what you enter in the Conductivity Assistant
T = water temperature in degrees C
Deploying the Logger
The HOBO U24 Conductivity logger is designed to be easy to deploy in many environments. The small size of the logger is
convenient for use in small wells and allows the logger to be
mounted and/or hidden in the field. Follow these guidelines
when deploying the logger:
•
Make sure the logger is located where it will receive a
steady flow of the water that is being monitored.
•
When deploying the logger in rivers, streams, and
ponds, insert the logger in a PVC or ABS pipe if
possible. The PVC pipe should have enough holes to
ensure good circulation of water.
•
To avoid bubbles collecting on the sensor, make sure
the sensor face is vertical and avoid sudden
temperature changes.
•
Do not place any conductive materials or metals within
2.5 cm (1 in.) of the sensor.
•
Avoid deploying the logger in freezing water with
moving ice.
•
Use the U2X Protective Housing (HOUSING-U2X) for
added protection to the logger in harsh environments.
To deploy the logger at each site:
1.
Launch the logger with a laptop or shuttle.
2.
Take a calibration reading as described on page 4.
3.
Deploy the logger in the water (if it hasn’t already been placed in the water) following the guidelines recommended
above.
4.
Repeat steps 1 through 3 for each logger deployed. Be sure to take a new calibration reading for each logger that
you deploy.
Reading Out the Logger and Calibrating Data with HOBOware
Your readout and maintenance schedule will be determined by the amount of fouling at the site. To read out the logger in
the field:
1.
Calibrate the field conductivity meter before using it to take field readings.
2.
Measure the specific conductivity with the field meter using one of the calibration methods on page 4.
3.
Remove the logger from the water (if it hasn’t already been removed for the calibration measurement).
4.
Read out the data from the logger using a shuttle.
