Inhibitors closed recirculating

DEWT L. [Drew Ind. Div.] Chromate/ (xgaiic blend corrosion inhibitor for closed recirculating water systems. 

Nitrites are not effective inhibitors. The presence of chloride and sulfate ions can damage the protective film formed by nitrites. They are often blended with borax in closed recirculating system. 

Recirculating systems are more easily controlled by inhibitors since higher concentrations can be applied because the water is reused. Sodium chromate or sodium nitrite are both effective in all-steel, closed recirculating systems. 

Inhibitors The use of various substances or inhibitors as additives to corrosive environments to decrease corrosion of metals in the environment is an important means of combating corrosion. This is generally most attractive in closed or recirculating systems in which the annual cost of inhibitor is low. However, it has also proved to be economicaUv attrac tive for many once-through systems, such as those encountered in petroleum-processing operations. Inhibitors are effective as the result of their controlling influence on the cathode- or anode-area reactions. 

It is important not to leave the system empty of water for any long period, as rapid surface rusting will take place. As soon as the closed-loop system is declared free of contamination, sufficient corrosion inhibitor is added to provide long-term corrosion protection. The corrosion inhibitor is usually an anodic, passivating formulation, typically based on nitrite or tannin (and often in combination with phosphate, silicate, borate, or molybdate, etc.). Finally, after confirmation that the entire system is adequately treated (which usually requires the inhibited water in the system to be recirculated for a further 16 to 24 hours), the system is signed off and handed over. 

The dosing of a multifunctional inhibitor chemical through an injection point into a return, recirculating cooling waterline, too close to a similar injection point for bromine, resulted in oxidation of the inhibitor and a... 

Inhibitors are very important for corrosion of irons and other metals. The corrosion of irons and other metals in aqueous solutions can frequently be minimized or inhibited by the addition of soluble chromates, molybdates, silicates, and amines or other chemicals, singly or in combination. Such materials are called inhibitors and are generally attractive for use in recirculating systems or closed systems. They are also used in neutral or very slightly acid solutions. The concentration of an inhibitor for maximum control depends on the solution, composition, temperature, velocity, metal system, and the presence of dissimilar metals in contact in the solution. Care should be taken in the selection and application of inhibitors, since in some instances they can increase localized attack. 

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