When it forms on the tubes, the silica acts as an insulator to heat transfer, which in turn increases the operational costs of the chillers. To keep the silica in suspension, LANL incorporates the use of a polymer base inhibitor and maintained low cycles of concentration (2.5 to 3) in the cooling towers. Still, the amount of buildup in the tubes requires regular manual cleaning, which is costly in terms of maintenance, downtime, and additional labor expenses, since the cleaning has to be scheduled over the weekends.
In early 2001, two 1,200-ton and two 600-ton chillers were installed in the LANL Super Computer Center (SCC). These chillers are equipped with an on-line Automatic Tube Brushing (ATB) system manufactured by Water Technology of Pensacola, Inc. (Pensacola, FL) in the condenser tubes to fight the silica problem.