36
SECTION 4,
continued
reference temperature. The linear temperature correction value
for the meter has a default value of 2% per 1 °C.
Conductivity of samples that contain other salts or ions may
change at a different rate with temperature. This rate depends on
the solution temperature, the ion concentration, and the reference
temperature selected, and should be determined experimentally.
Once determined, enter the temperature correction value using
this setup option.
The Temperature Correction option must be on for the meter to
use a temperature correction value (see Section 4.2).
Table 6 shows some typical temperature coefficients (percent
change of conductivity per °C).
TDS Correction Factor — This setup lets the user choose a
linear or non-linear conversion from conductivity to TDS. TDS
measurements use conductivity readings that are temperature-
compensated. When the linear conversion is chosen, the meter
uses the reference temperature and the temperature-correction
option to determine temperature-corrected conductivity. The
non-linear (NaCl) conversion uses the non-linear temperature
correction function and a reference temperature of 25 °C,
regardless of the current temperature factor setting (Setup 6), to
convert temperature-compensated conductivity readings to
TDS readings.
In Reading mode, the TDS icon indicates the meter is reading
TDS. If the correction icon is also shown, the meter is using a
Table 6 Percentage Change of Conductivity per Degree C
Solution
Percent/°C
Ultrapure Water
4.55
Salt (NaCl)
2.125
NaOH
1.72
Dilute Ammonia
1.8810
10% HCl
1.325
5% Sulfuric Acid
0.9698
Sugar Syrup
5.64
