The following case study is for a Griswold WAVE electronic field unit using no chemicals after initial system passivation. The system operated under stressed conditions of a heavy construction environment, pine tree contamination, and low TDS. The system uses a Pulsafeeder MVS conductivity controller and a Lakos separator filter.
Griswold WAVE 600 insatlled on the cooling tower riser pipe in April 2011. Open cooling tower is a closed circuit evaporative cooler. The basin is 304 SS with galvanized walls, support members and the closed loop tubes are galvanized steel.
Griswold 120VAC elecrical panel with Pulsafeeder controller, bleed meter, & coupon rack located just below the blue Reaction Chamber. The panel is connected to the Reaction Chamber with a 1" diameter signal cable.
Pine tree location is on the side of the tower and partially over the discharge flume creating a biologically "stressed" application. Pine trees loose needles and spray pollen locally in the sping which both add significant biological loads to the cooling tower.
Nearby Stadium construction additionally taxes the biological control of the tower treatment.
With over 1 year of operation and the system remains spotless even with year long construction and a pine tree overhang.
Corrosion Study Summary:
After one full year of operation the Griswold WAVE performance yields excellent biological and algae control. Using dip slide augers we never exceeded 1000 CFU of planktonic bacteria on any monthly test. The system is intermitantly on / off which would normally yield higher than normal corrosion rates when using a traditional chemical program since it would be dificult for the inhibitor to form and maintain its desired protective complex under these conditions. The indipendent corrosion coupon studies yielded very low and desirable corrosion rates as shown in the analysis document below. Additionally, during coupon testing the conductivity ran 30% lower than our target conductivity due to over purge of the Lakos filter. This would normally reduce the carbonaste cycle protection but has not negatively impacted the corrosion rates. With superior biological control the corrosion rates remain acceptable even in the low TDS environment. A traditional chemical program would have to over feed the inhibitor and increae biocide feedings in order to maintain acceptable corrosion rates under these conditions. We continue to run monthly field testings to make sure electrical field strength, cycles, conductivity, hardness, chlorides, LSI, alkalinity, and bacteria counts remain within recommended limits.
INDEPENDENT 3rd PARTY COUPON ANALYSIS FOR MILD STEEL YIELDING 1.587 MPY (< 2.0 MPY IS CONSIDERED EXCELLENT):