Drewgard corrosion inhibitors effectively control corrosion in open re-circulating and closed cooling water systems. These products, which are manufactured with inorganic or organic chemistries or combinations of both, form passivating complexes at the anodic and cathodic sites on metal surfaces. The resulting surface passivation not only protects system equipment from corrosion but also helps prolong equipment life. 
Some of the inorganic phosphate-based products are NSF/ANSI certified for use in potable water systems. Likewise, some of the organic-based products are formulated without nitrite or heavy metals, making them environmentally-friendly options. Recommendation for the appropriate Drewgard product and the corresponding application method depend upon a number of factors, including the cause of corrosion, the type of system and the water chemistry.