HND-C110
page 10
HND-C110 K05/0422
9.3 Resistivity measurement
The resistivity is the reciprocal value of the conductivity and the device displays it
in kOhm•cm.
Measuring ranges:
0.000 – 2.000 kOhm*cm
0.00 – 20.00 kOhm*cm
0.0 – 100.0 kOhm*c
If the range selection is set to „Auto Range“, the range with the best resolution is
automatically selected. However, interface operation requires a manual/fixed
selection of the measuring range from the table above (No interface operation
with Auto-range!).
9.4 TDS measurement
At the TDS (total dissolved solids) measurement the filtrate dry residue is
determined by means of the conductivity and a conversion factor (C.tdS). Well
suited for easy concentration measurements of e.g. salt solutions. The
determined value is displayed in mg/l.
Measuring ranges: 0,0 - 200,0 mg/l 0 – 2000 mg/l
Displayed value TDS = conductivity [in µs/cm, nLF-temp. comp. at 25°C] • C.tdS
(input at menu)
Approximately:
C.tdS
0.50
Monovalent salts with 2 ion types (NaCl, KCl, etc.)
0.50
Natural waters / surface waters, drinking water
0.65-0.70
e.g. salt concentration of aqueous fertilizer solutions
Attention: This are only approximate values – good for estimations, but no precise
measurement.
For precise measurements the conversion value has to be determined for the
corresponding solution for the relevant concentration range.
This may be done by comparison with known reference solutions or by actually
evaporating a certain amount of solution with determined conductivity and
subsequent weighing of the dry residue.
