H83.0.02.6C-10
Operating manual GMH 5430
page 8 of 18
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_____________________________________________________________________________
GHM GROUP
– Greisinger | GHM Messtechnik GmbH
Hans-Sachs-Str. 26 | 93128 Regenstauf | GERMANY
Phone +49 9402 9383-0 | Fax +49 9402 9383-33
www.greisinger.de
|
e
6.4 Resistivity measurement
The resistivity is the reciprocal value of the conductivity and the device displays it in kOhm
•
cm (MOhm
•
cm).
Range
CELL
- rAnG
1
2
3
4
0.01
0.10 - 50.
00 kOhm•cm
0.1 - 500.
0 kOhm•cm
0.000 - 5.
000 MOhm•cm 0.000 - 50.00 MOhm•cm
0.1
0.010 - 5.
000 kOhm•cm
0.01 - 50.
00 kOhm•cm
0.0 - 500.
0 kOhm•cm
0.000 - 5.
000 MOhm•cm
1
0.0010 - 0.
5000 kOhm•cm 0.001 - 5.000 kOhm•cm
0.00 - 50.
00 kOhm•cm 0.0 - 500.0 kOhm•cm
10
---
0.0001 - 0.
5000 kOhm•cm 0.000 - 5.000 kOhm•cm 0.00 - 50.00 kOhm•cm
If the range selection is set to „Auto Range“, the range with the best resolution is automatically selected.
6.5 TDS measurement
At the TDS (
t
otal
d
issolved
s
olids) 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.
Range
CELL
- rAnG
1
2
3
4
0.01
0.000 - 5.000 mg/l
0.00 - 50.00 mg/l
0.0 - 500.0 mg/l
0 - 5000 mg/l
0.1
0.00 - 50.00 mg/l
0.0 - 500.0 mg/l
0 - 5000 mg/l
---
1
0.0 - 500.0 mg/l
0 - 5000 mg/l
---
---
10
0 - 5000 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.
6.6 Salinity measurement
At the salinity measurement “SAL” the salinity (salt content) of seawater is determined (based on:
International Oceanographic Tables; IOT).
Standard seawater has a salinity of 35 ‰ (35 g salt per 1 kg
seawater).
Commonly the measured value is displayed dimensionless in ‰ (g/kg).
Additionally the term “PSU” (Practical Salinity Unit) is sometimes used, the displayed value is the same.
The salinity measurement has its “own” temperature compensation, i.e. the temperature is automatically
taken into account for the salinity measurement. The menu settings regarding the temperature compensation
are ignored.
The salt composition of the different seas is not the identical. Depending on place, weather,
tides, etc. there may be considerable divergences to the 35 ‰ according to IOT. Additionally
the salt composition may influence the ratio between salinity and actual salt content.
For many salts of the seawater aquaristics the corresponding tables are available (salt weight to salinity
according to IOT or conductivity). Considering these tables, very precise salinity measurements can be
performed (Therefore we recommend the 4-pole graphite measuring cells LF 400 or LF 425.).
