Specific Conductance, Resistance & Approximate Electrolyte Content |
Specific
Conductivity |
Specific
Resistance in |
Approximate
Electrolyte |
0.1 |
10,000,000 |
0.04 |
0.2 |
5,000,000 |
0.08 |
1 |
1,000,000 |
0.4 |
2 |
500,000 |
0.8 |
4 |
250,000 |
1.6 |
6 |
166,000 |
2.5 |
8 |
125,000 |
3.2 |
10 |
100,000 |
4 |
20 |
50,000 |
8 |
30 |
33,333 |
14 |
40 |
25,000 |
19 |
50 |
20,000 |
24 |
60 |
16,666 |
28 |
70 |
14,286 |
33 |
80 |
12,500 |
38 |
90 |
11,111 |
43 |
100 |
10,000 |
50 |
200 |
5,000 |
100 |
Creating Spot-Free
Rinse Water
As electrolytes in the form of dissolved salts in water are
removed, the water's
ability to conduct electricity decreases. This causes an increase
in the water's
resistance, measured in ohms. Spot-free final rinse water for
typical paint
finishing lines must have resistivity greater than 50,000 ohms.
This
corresponds with a total dissolved solids (TDS) level of less
than 8.0
milligrams per liter parts per million (mg/1ppm).
A deionization unit with a cation/anion dual bed will
remove 99 percent of dissolved salts from
feedwater. The remaining one percent
TDS will yield more than 100,000 ohms
resistance. If the feedwater contains more than 500
ppm TDS, recirculated water loops will remove the
remaining electrolytes, approaching 1.5 million
ohms resistivity.
Likewise, a reverse osmosis unit (RO) can
remove 97 to 98 percent of an incoming
feedwater's TDS. To calculate the
approximate product water's electrolyte
content from an RO unit, multiply the
raw water TDS by 0.02. In some
instances, RO product water will
already have a 50,0000-ohm
resistivity. When feedwater TDS is
greater than 250 ppm, use RO
reclaim systems to provide spot-free final rinse
and low TDS make-up water to the entire washer.