Thermo Scientific Orion 320, User Manual

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2-6 Thermo Scientific Orion 320, 350 and 370 PerpHecT
®
LogR
®
Meter User Guide
PerpHecT pH meters allow for direct temperature measurement and
temperature compensation from your pH electrode . With simultaneous
measurement of pH and temperature, the patented digital LogR technology
makes this possible using most standard glass pH electrodes . The system
is based on using the electrical resistance of the glass sensing bulb as the
temperature probe . The logarithm of the resistance of the bulb varies
almost linearly with the reciprocal of the absolute temperature (see
Figure .5 ) . Almost all common pH glasses show a similar decrease in
resistance with increasing temperature, and can be used with other meters .
However, only the exact shape of the curve of PerpHecT electrodes is in
the meter’s memory . To maximize system performance and accuracy, use a
PerpHecT or PerpHecT ROSS pH electrode .
Figure .5 .– . .LogR .Resistance .vs . .Temperature .Graph