Appendix A Fluids - Thermo Scientific NESLAB EX Series Installation, Operation And Maintanance Manual

Water Quality Standard and Recommendations

Appendix A Fluids

Microbiologicals
(algae, bacteria, fungi)
Inorganic Chemicals
Calcium
Chloride
Magnesium
Sulfate
Total Hardness
Unfavorably high total ionized solids (TIS) can accelerate the rate of galvanic
corrosion. These contaminants can function as electrolytes which increase the
potential for galvanic cell corrosion and lead to localized corrosion such as
pitting.
High water hardness (Calcium and Maganese) can also produce scaling. For
example, tap water in the U.S. averages 171 ppm (of NaCl). The recommended
level for use in a water system is between 0.5 to 5.0 ppm (of NaCl).
Recommendation: Initially fill the tank with distilled/deionized water. Do not use
untreated tap water as the total ionized solids level may be too high.
Maintain this water quality at a resistivity of between 1 to 10 MOhmcm (com-
pensated to 25°C) by using a purification system. Although the initial fill may
be as high as 18 MOhmcm (compensated to 25°C), the desired level for long
time usage is 1 to 3 MOhmcm (compensated to 25°C).
The above two recommendations will reduce the electrolytic potential of the
water and prevent or reduce the galvanic corrosion observed.
A - 1
Permissible (PPM)
0
<25
<25
<12
<25
<17
Desirable (PPM)
0
<0.6
<10
<0.1
<1
<0.05