TDS, CF, EC, PPM Conversion

First of all:
In Germany, 0.1 mS/m at 25°C = 0.425 mg/l TDS (mg/l salinity) used to be used as an approximate value for the conversion.
According to Grohmann (somewhat imprecise): µS/cm = 5.48 + 1.43 * TDS. The conductivity of an aqueous electrolyte solution (acids, bases and salts are considered electrolytes) is calculated from the sum of the equivalent conductivities of all dissolved ions, multiplied by their respective concentrations. And: The equivalent conductivity depends on the concentration of the ion in question and, of course, all other ions in the solution. It follows from this: It only makes sense to draw conclusions about the salt content of a salt solution from its conductivity if (almost) nothing is dissolved in the water apart from the salt in question.

It is important to note that all ppm (TDS, Total Dissolved Solids) pens and probes first measure in EC (electrical conductivity) and then run a conversion program to display the reading in ppm. It is important to know that there are three different conversion factors (standards) that different manufacturers use for converting EC to ppm. These can be simply stated as follows:

 

USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

For example:
Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Billet 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

 

If the conversion factor on your ppm meter is e.g. 1 EC = 700 ppm, take the EC value given on the instruction manual and multiply it by 700. e.g.
1 EC = 1 x 700 = 700 ppm; 1.5 EC = 1.5 x 700 = 1050 ppm; 2 EC = 2 x 700 = 1400 ppm etc.

 

Conversions and connection of units:

1 S/cm corresponds to ...
S/cm: 1.0
mS/cm: 1.00e+3
microS/cm: 1.00e+6
EC: 1.00e+3 mS/cm
CF: 1.00e+4
mho/cm: 1.00
mho/m: 0.0100
ppm TDS: 6.40e+5

 

 

Conversion table

EC
mS/cm		Division 500
0,5 ppm		Division 640
0,64 ppm		Division 700
0,7 ppm		CF
0
0,1 50 ppm 64 ppm 70 ppm 1
0,2 100 ppm 128 ppm 140 ppm 2
0,3 150 ppm 192 ppm 210 ppm 3
0,4 200 ppm 256 ppm 280 ppm 4
0,5 250 ppm 320 ppm 350 ppm 5
0,6 300 ppm 384 ppm 420 ppm 6
0,7 350 ppm 448 ppm 490 ppm 7
0,8 400 ppm 512 ppm 560 ppm 8
0,9 450 ppm 576 ppm 630 ppm 9
1 500 ppm 640 ppm 700 ppm 10
1,1 550 ppm 704 ppm 770 ppm 11
1,2 600 ppm 768 ppm 840 ppm 12
1,3 650 ppm 832 ppm 910 ppm 13
1,4 700 ppm 896 ppm 980 ppm 14
1,5 750 ppm 960 ppm 1050 ppm 15
1,6 800 ppm 1024 ppm 1120 ppm 16
1,7 850 ppm 1088 ppm 1190 ppm 17
1,8 900 ppm 1152 ppm 1260 ppm 18
1,9 950 ppm 1216 ppm 1330 ppm 19
2 1000 ppm 1280 ppm 1400 ppm 20
2,1 1050 ppm 1344 ppm 1470 ppm 21
2,2 1100 ppm 1408 ppm 1540 ppm 22
2,3 1150 ppm 1472 ppm 1610 ppm 23
2,4 1200 ppm 1536 ppm 1680 ppm 24
2,5 1250 ppm 1600 ppm 1750 ppm 25
2,6 1300 ppm 1664 ppm 1820 ppm 26
2,7 1350 ppm 1728 ppm 1890 ppm 27
2,8 1400 ppm 1792 ppm 1960 ppm 28
2,9 1450 ppm 1856 ppm 2030 ppm 29
3 1500 ppm 1920 ppm 2100 ppm 30
3,1 1550 ppm 1984 ppm 2170 ppm 31
3,2 1600 ppm 2048 ppm 2240 ppm 32
3,3 1650 ppm 2112 ppm 2310 ppm 33
3,4 1700 ppm 2176 ppm 2380 ppm 34
3,5 1750 ppm 2240 ppm 2450 ppm 35
3,6 1800 ppm 2304 ppm 2520 ppm 36
3,7 1850 ppm 2368 ppm 2590 ppm 37
3,8 1900 ppm 2432 ppm 2660 ppm 38

 

Context: 

 ID: 143

Category: Technology
Also available:  German (Hochdeutsch)