EIJKELKAMP 18.52.01 Manuel D'instructions page 136

Cell Constant Optimum Conductivity Range, 2-cell
0.1 0.5 to 200 µS/cm
1.0 0.01 to 2 mS/cm
10.0 1 to 200 mS/cm
You can calibrate your meter using TDS calibration standard solutions. The calibration standard only
needs to give the TDS value at a standard temperature such as 25 °C. To determine the conductivity-
to-TDS conversion factor use the following formula:
Definitions:
• Actual TDS: Value from the solution bottle label or as a standard you make using high purity water
and precisely weighed salts.
• Actual Conductivity: Value measured using a properly calibrated Conductivity/Temperature meter.
Both the Actual TDS and the Actual Conductivity values must be in the same magnitude of units. For
example, if the TDS value is in ppm the conductivity value must be in µS; if the TDS value is in ppt the
conductivity value must be in mS. Check your factor by multiplying the conductivity reading by the
factor in the above formula. The result should be in TDS value.
Calculating Temperature Coefficients
To determine the temperature coefficient of your sample solution use this formula:
Where: tc = Temperature coefficient 25 = 25 °C
CT = Conductivity at Temp1 CT
1
T = Temp 1 T
1
NOTE: A controlled temperature water bath is ideal for this procedure.
1. Immerse the probe into a sample of your solution and adjust the temperature coefficient to 0%
2. Wait for 5 minutes. Note T
3. Condition the sample solution and probe to a temperature (T
from T , and note the conductivity reading CT
1
NOTE: Record your results for future reference. Ideally T
temperature, and should not different by more than 5 °C.
SALINITY
The salinity scale which ranges from 0 to 80 ppt is a measure of all salts, not just sodium chloride. This
scale was originally devised for seawater, and is based on seawater at 15 degrees Centigrade has a
conductivity equivalent to that of a potassium chloride solution of a known concentration. This solution
(0.44 molar) is defined as having a salinity of 35 ppt. The conductivity – salinity conversion complies
with the International Oceanographic Table (IOT) and the Practical Salinity Scale (PSS).
Below table shows the EC – Salinty conversion at different temperatures.
EC (µS/cm) @ 15C
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
DISSOLVED OXYGEN PROBE
The probe is a galvanic measuring element which produces an output proportional to the oxygen
present in the medium in which it is placed. The galvanic probe design lets you take measurements
immediately – without the typical 15 minute wait of other dissolved oxygen probes.
The probe consists of two parts:
Factor = Actual TDS ÷ Actual Conductivity @ 25 °C
= Conductivity at Temp2
2
= Temp 2
2
and CT (conductivity at T
1 1
EC (µS/cm) @ 20C
1120
2242
3364
4484
5604
6722
7841
8960
10080
11198
Optimum Conductivity Range, 4-cell
Not Available
0.01 to 20 mS/cm
1 to 200 mS/cm
).
1
) that is about 5 °C to 10 °C different
2
.
2
and T should bracket your measurement
1 2
EC (µS/cm) @ 25C
1246
2492
3630
4984
6226
7468
8710
9951
11193
12433
136
Salinity (ppm) @15C
0,620
1,282
1,968
2,670
3,386
4,113
4,851
5,598
6,354
7,117
.
.