MTS Landmark Site Prep Guide - Manual (Page 29)

HPU Considerations
Landmark Test System Site Prep Guide Additional Considerations 29
Softened or distilled water might not be good to use as a cooling liquid because
although most of the minerals have been removed there is a higher than desirable
level of carbon dioxide and oxygen present in the water. High levels of carbon
dioxide and oxygen will act to decrease the protective layer of minerals that form
on the surface of the tube, and increase the formation of copper oxide.
Some contaminants in the cooling water supply can operate together to create
corrosion rates a hundred times higher than would be seen by either contaminant
acting alone. Cooling towers, unless regularly treated and controlled, are the
systems that have had the most problems with corroded heat exchangers.
Local industrial water treatment specialists can provide information on your
water conditions and solutions to contaminant problems.
Water Chemistry
Compounds found in Water Allowable Quantity (parts per million)
Ammonia none
Bacteria must be bacteriologically safe
Calcium <800 ppm
Chlorides <5 ppm
Dissolved solids >50 but <500 ppm; limit to 150 ppm if abrasive
solids present
Iron 3 ppm
Nitrates <10 ppm
Nitrogen compounds none
Oxidizing salts or none
pH level 6–8.5 recommended
Silica as SiO
2
<150 ppm to limit silica scale
Sulfides <1 ppm
Sulfur dioxide <50 ppm