User Manual

HOBO U12 Temp/RH/Light/External Data Logger
3
Using the RH sensor
In order to take humidity measurements, the temperature
sensor must be used in conjunction with the RH sensor.
Conditions outside the recommended range may offset the RH
signal. Vapors may also affect the RH sensor. The diffusion of
chemicals into the sensor may cause a shift in both offset and
sensitivity. High levels of pollutants may cause permanent
damage to the sensor.
Upon returning to normal conditions, the RH sensor will
slowly return towards calibration state by itself. However,
prolonged exposure to extreme conditions may accelerate
aging and eventually lead to a permanent shift. To recondition
the sensor, do the following:
1. Remove the battery
2. Warm 24 hours 80–90°C (176–194°F) at < 5% RH
3. Re-hydrate 48 hours 20–30°C (70–90°F) at 75–95% RH
Protecting the Logger
The logger can be permanently damaged by corrosion if it gets
wet. Protect it from condensation. If it gets wet, remove the
battery immediately and dry the circuit board with a hair dryer
before reinstalling the battery. Do not let the board get too hot.
You should be able to comfortably hold the board in your
hand while drying.
Note! Static electricity may cause the logger to stop
logging. To avoid electrostatic discharge, transport the logger
in an anti-static bag, and ground yourself by touching an
unpainted metal surface before handling the logger. For more
information about electrostatic discharge, visit
http://www.onsetcomp.com/Support/support.html.
Mounting
There are four ways to mount the logger using the materials in
the mounting kit included with the logger.
Use the hook and loop tape to affix
the logger to a surface.
Attach the magnet and then place the
logger on a magnetic surface.
Use the tie wrap and tie wrap mount
to tie the logger to an object.
Fasten the logger to a surface with the
two Phillips-head screws. The back of
the logger has two inserts for the
screws, 32 mm (1¼ inches) apart.
Battery
The logger requires one 3-Volt CR-2032 lithium battery.
Expected battery life varies based on the temperature and the
frequency at which the logger is recording data (the logging
interval). A new battery will typically last one year with
logging intervals greater than one minute. Deployments in
extremely cold or hot temperatures or logging intervals faster
than one minute may significantly reduce battery life.
To replace the battery:
1. Disconnect the logger from the computer.
2. Unscrew the logger case.
3. Lift the circuit board and carefully push the battery out
with a small blunt instrument, or pull it out with your
fingernail.
4. Insert a new battery, positive side facing up.
5. Carefully realign the logger case and re-fasten the screws.
WARNING: Do not cut open, incinerate, heat above
85°C (185°F), or recharge the lithium battery. The
battery may explode if the logger is exposed to extreme
heat or conditions that could damage or destroy the
battery case. Do not dispose of the logger or battery in
fire. Do not expose the contents of the battery to water.
Dispose of the battery according to local regulations for
lithium batteries.
32 mm
(1¼
inch)