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HOBO® U24 Conductivity Logger (U24-00x) Manual
The HOBO U24 data logger family measures actual conductivity and
temperature, and can provide specific conductance at 25°C and salinity
with the HOBOware® Conductivity Assistant. These easily deployable,
rugged loggers provide the data you need for monitoring water purity,
the impact of pollutants, salt water intrusion, and coastal ecosystems.
The U24-001 model is ideal for deployment in fresh water, while the
U24-002 model is designed for saltwater bays and estuaries. There is
also an optional U2X Protective Housing accessory (HOUSING-U2X)
available for both HOBO U24 models to further protect the logger and
simplify mounting in harsh environments.
Specifications
Measurements
Conductivity Calibrated
Measurement Ranges
Conductivity Calibrated Range –
Temperature Range
Conductivity Extended Ranges
Temperature Measurement Range
Specific Conductance Accuracy
(in Calibrated Range)
Conductivity Resolution
Temperature Accuracy (in
Calibrated Range)
Temperature Resolution
Conductivity Drift
Response Time
Operating Range
Memory
Sample Rate
Clock Accuracy
Battery
Battery Life
Maximum Depth
Weight
Size
Wetted Housing Materials
© 2011 Onset Computer Corporation. All rights reserved. Onset, HOBOware, and HOBO are trademarks or registered trademarks of Onset Computer
Corporation. Delrin is a registered trademark of DuPont. All other trademarks are the property of their respective companies.
14787-A MAN-U24-x
U24-001
Actual Conductivity, Temperature, Specific
Conductance at 25°C (calculated)
Low Range: 0 to 1,000 µS/cm
Full Range: 0 to 10,000 µS/cm (see Plot B on
next page for specific conductance; see Plot C
on next page for a comparison of ranges)
5° to 35°C (41° to 95°F)
Low Range: 0 to 2,500 µS/cm
Full Range: 0 to 15,000 µS/cm
0° to 50°C (32° to 118°F)
Low Range: 3% of reading, or 5 µS/cm, and
Full Range: 3% of reading, or 20 µS/cm,
whichever is greater, after correction with
Conductivity Data Assistant
1 µS/cm
0.1°C (0.2°F)
0.01°C (0.02°F)
Less than 3% sensor drift per year in saltwater, exclusive of drift from fouling
1 second to 90% of change (in water)
0° to 50°C (32° to 122°F) - non-freezing
18,500 temperature and conductivity measurements when using one conductivity range; 14,400
sets of measurements when using both conductivity ranges (64 KB total memory)
1 second to 18 hrs, fixed or multiple-rate sampling with up to 8 user-defined sampling intervals
± 1 minute per month
3.6 Volt lithium battery
3 years (at 1 minute logging)
70 m (225 ft)
193 gm (6.82 oz), buoyancy in freshwater: -59.8 gm (-2.11 oz)
3.18 cm diameter x 16.5 cm, with 6.3 mm mounting hole (1.25 in. diameter x 6.5 in., 0.25 in.
hole)
Delrin®, epoxy, stainless steel retaining ring, polypropylene, Buna rubber O-ring, titanium
pentoxide (inert coating over sensor); all materials are suitable for long-term use in saltwater
The CE Marking identifies this product as complying with all relevant directives in the European
Union (EU).
U24-002
Actual Conductivity, Temperature, Specific
Conductance at 25°C (calculated), Salinity
(calculated using PSS-78, the Practical Salinity
Scale 1978)
Low Range: 100 to 10,000 µS/cm
High Range: 5,000 to 65,000 µS/cm (see Plots
A and B on next page for salinity and specific
conductance; see Plot C for a comparison of
ranges)
5° to 35°C (41° to 95°F)
Low Range: 50 to 30,000 µS/cm
High Range: 1,000 to 65,000 µS/cm
(readings below these ranges reported as 0)
0° to 50°C (32° to 118°F)
3% of reading, or 50 µS/cm, whichever is
greater, after correction with Conductivity
Data Assistant
2 µS/cm
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Related Manuals for Onset HOBO U24
Summary of Contents for Onset HOBO U24
- Page 1 Union (EU). © 2011 Onset Computer Corporation. All rights reserved. Onset, HOBOware, and HOBO are trademarks or registered trademarks of Onset Computer Corporation. Delrin is a registered trademark of DuPont. All other trademarks are the property of their respective companies.
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Page 2: Operation
Do not attempt to open the logger case or sensor housing. Disassembling of the logger case or sensor housing will cause serious damage to the sensor and logger electronics. There are no user-serviceable parts inside the case. Contact Onset Technical Support at 1-800-LOGGERS (1-800-564-4377) or an authorized Onset dealer if your logger requires servicing. -
Page 3: Launching The Logger
(the calibrated ranges are also printed on the logger housing). The logger will not record readings outside of the extended range selected. (For the U24-002, readings below the extended range are reported as 0.) If in doubt HOBO U24 Conductivity Logger Manual onsetcomp.com... - Page 4 4. When using the Conductivity Assistant, look for the spot in the data where there are three similar readings in a row and link the last of those readings to the meter reading. The Conductivity Assistant uses that value to calibrate the specific conductance and salinity readings for that data series. HOBO U24 Conductivity Logger Manual onsetcomp.com...
- Page 5 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.
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Page 6: Maintenance
“bad battery” event in the datafile. If the datafile contains “bad battery” events, or if logged battery voltage repeatedly falls below 3.3 V, the battery is failing and the logger should be returned to Onset for battery replacement. Note that the logger does not have to be recording the battery channel for it to detect bad battery events.
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