Nitrite based closed circuit inhibitor 1000ppm at 0.26% multi-functional, nitrite-based chemical treatment used for the control of corrosion in closed cooling systems and chilled water systems RXSOL-40-4021 is a high performance nitrite based closed circuit inhibitor with indicator. Nitrite > 1000ppm at 0.50%. It is multi-functional corrosion inhibitor for protecting recalculating cooling and heating water systems. RXSOL-40-4021 treatment is an excellent treatment for diesel engine primary and secondary cooling water. It is also ideally suited for use in chilled water systems because it forms a clear, non-staining solution, which protects the system from corrosion and hard water scale.