Water Quality And Blowdown - SPX Marley LW032 B Series User Manual

Note
14
operation

Water Quality and Blowdown

Maintaining Water Quality:
Galvanized steel structural and casing components used in LW fluid coolers
have been galvanized with a heavy zinc coating averaging 2.0 mils in thick-
ness. Other materials used (PVC fill, drift eliminators, and louvers, aluminum
fans, etc.) are selected to offer maximum service life in a "normal" fluid cooler
environment, defined as follows:
Recirculating water with a pH between 6.5 and 8; a chloride content (as NaCl)
below 500 ppm; a sulfate content (SO
CaCO ) below 500 ppm; calcium hardness (as CaCO
3
significant contamination with unusual chemicals or foreign substances; and
adequate water treatment to minimize scaling.
• Startup Conditions: The water conditions during initial fluid cooler opera-
tion are crucial in preventing premature corrosion of galvanized steel (white
rust). For at least the first eight weeks of operation, pH should be controlled
between 6.5 and 8.0 with hardness and alkalinity levels between 100 and
300 ppm (expressed as CaCO
• Chlorine (if used) shall be added intermittently, with a free residual not to
exceed 1 ppm maintained for short periods. Excessive chlorine levels may
deteriorate sealants and other materials of construction.
• An atmosphere surrounding the fluid cooler no worse than "moderate in-
dustrial", where rainfall and fog are no more than slightly acid, and they do
not contain significant chlorides or hydrogen sulfide (H
• Many proprietary chemicals exist for control of scale, corrosion, and biologi-
cal growth and should be used prudently. Also, combinations of chemicals
may cause reactions which reduce treatment effectiveness, and certain
chemicals such as surfactants, biodispersants and antifoams may increase
drift rate.
The structure your fluid cooler contains galvanized steel, and the
heat transfer coil is constructed with copper, therefore, your water
treatment program must be compatible with zinc and copper. In
working with your water treatment supplier, it is important that you
recognize the potential effects of the specific treatment program
you choose on zinc and copper.
) below 250 ppm; total alkalinity (as
4
) above 50 ppm; no
3
).
3
2
S).