54
Multi-Parameter
Water Quality
TROLL
®
TROLL
9500
Operator’s Manual
0095110 rev. 007 01/09
8 MONITORING TEMPERATURE
Pressure/Turbidity
or plug
Temperature
End view of sensor block
Platinum Resistance Thermometer
WHY MONITOR TEMPERATURE?
Water temperature plays an important role in water chemistry, which in
TURNINmUENCESTHEBIOLOGICALACTIVITYANDGROWTHOFAQUATICORGANISMS
In general, the higher the water temperature, the greater the biological
activity and the rate of chemical reactions. An important example of
the effects of temperature on water chemistry is its impact on oxygen.
Warm water holds less oxygen than cool water; the maximum amount
of oxygen that can be dissolved in the water decreases as water
temperature increases.
Artificially high temperatures are often referred to as “thermal pol-
lution,” which may result from discharge of municipal or industrial
EFmUENTS4HERMALPOLLUTIONCANHAVEASIGNIlCANTECOLOGICALIMPACT
In running waters, particularly small urban streams, elevated tempera-
tures from road and parking lot runoff can be a serious problem for
populations of cool or cold-water fish.
Changes in the growth rates of cold-blooded aquatic organisms and
many biochemical reaction rates can often be approximated by the
“Q
10
rule,” which predicts that growth rate will double if temperature
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Knowledge of water temperature is essential to the measurement of
dissolved oxygen, conductivity (salinity), pH, and many other water-
quality parameters. In limnological studies, water temperature as a
function of depth can be an important indicator. Industrial plants often
require data on water temperature for process use or heat-transmis-
sion calculations.
These are only a few of many reasons for measuring and recording
water temperature over the short or long term.
THE TEMPERATURE SENSOR
All models of the Multi-Parameter TROLL 9500 include a permanently
installed, factory-calibrated sensor for measuring solution tempera-
ture.
Do not try to remove the permanently installed
temperature sensor.
The MP TROLL 9500 temperature sensor is the Standard Platinum
Resistance Thermometer specified by the ITS-90 (International Tem-
perature Scale of 1990). A platinum resistance thermometer (PRT) is
a type of resistance temperature detector (RTD).
TIP:
After a drop or shock, if the end of the temperature
sensor is slightly bent, it may be carefully bent by hand (no
tools, please!) back to its original alignment. Note that a
severe shock may affect the accuracy of the temperature sensor.