Abstract: An improved method is disclosed for preparing zinc polyphosphate in a stable, concentrated solution, for water treatment purposes having a pH above 7.0 and in a preferred range of pH between 8.0 and 10.0. Without any acid solubilization required, an approximate 60% solution of tetrapotassium pyrophosphate (TKPP) is formulated and mixed thoroughly in a tank or similar container. Under constant stirring, a predetermined aqueous solution of a normal zinc salt, such as zinc chloride, gradually injected and mixed together into the TKPP solution at a preferred rate of about 5% of the zinc salt solution per minute and in a sufficient amount determined to add about 1 part of zinc to between 5-8 parts of TKPP by weight for maximum corrosion protection.

Abstract: A cooling tower system and associated method is disclosed for controlling an aqueous coolant circulated through a cooling tower without requiring discharge of the coolant during recirculation. The coolant pumped from the cooling tower is filtered and monitored for characteristics. Generally acceptable levels of pH, temperature and TDS are maintained in the coolant to reduce the corrosive and scale-forming tendencies thereof and with those levels being maintained and monitored, the calcium content of the coolant is then adjusted in order to balance the Langelier Saturation Index (Sl) at a zero level. A computer is programmed to resolve control algorithms for Sl=0 and, using stored tabular data corresponding to the respective values of the monitored characteristics of pH, temperature, alkalinity and TDS, the computer calculates the value of calcium necessary to maintain a zero index.