User Manual
Table Of Contents
output August 19, 2019 8:28 Page 17
been seen from top to bottom of sewer head spaces).
Electrochemical sensors are sensitive to temperature changes,
and for this reason each transducer in the sensor heads is com-
pensated for temperature effects with reference to an internal
temperature measurement in the SulfiLogger
™
sensor’s sensor
head.
MEASURING IN DIFFERENT MEDIA - UNIT CONVERSIONS
The electrochemical microsensors in the SulfiLogger
™
sensor’ sen-
sor head measures the partial pressure of H
2
S. In the gas phase,
this can be converted to a
ppm
-reading if the total barometric
pressure is known, and in the liquid phase the measured value can
be converted to a concentration measured in either
µM
or
mg/L
by using Henry’s constant and the molar weight.
Each sensor is ordered with a specification of medium type, and
the signal output from the SulfiLogger
™
sensor is chosen as
ppm
for gas phase sensor heads and
S−mg/L
for liquid phase sensor
heads, the "S" in front of
mg/L
meaning that only the sulfur frac-
tion of the weight is counted in the specified measurement.
The
ppm
values for gas phase sensors is calculated by using a
standard barometric pressure of
1
atm =
101325
Pa, and the
mg/L
values for liquid phase sensors is calculated by using a tempera-
ture corrected value of Henry’s constant. Please note that other
dissolved substances and high salinity values may also influence
the conversion to
mg/L
units. For more information on this, please
contact Unisense.
SULFILOGGER™ SENSORS
An overview of the SulfiLogger
™
sensor types and their features
can be found in the table below.
17