Double Boiler Heating System

Heat uniformity for metal finishing applications can be achieved using the company’s Double Boiler tank design.

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Heat uniformity for metal finishing applications can be achieved using the company’s Double Boiler tank design. This tank-in-tank design features an inner process tank to hold process chemistry and an outer tank, which is filled with a heating medium such as glycol. The liquid medium in the outer tank is heated using electric immersion heaters or steam heat exchangers to a temperature 40-60°F above the desired operating temperature of the process bath contained within the inner tank. The inner process tank is heated evenly on all sides as well as on the bottom by the surrounding heated glycol jacket.  This approach is commonly found in Electroless Nickel applications where even heat distribution is critical for effective plating. The unit eliminates heat stratification and plating build-up found in direct heating installations. Materials of construction vary depending on process as well as budget requirements. Recent applications feature an inner tank, fabricated of 316-stainless steel, which has been elctropolished to a mirror finish. In this configuration the inner tank is made anodic with the addition of a small dc power supply and cathode. This approach reduces the down time and disposal problems associated with a flexible PVC tank liner that requires regular replacement due to metal buildup. The tank is a modular design that includes a circulation pump, heaters, and temperature controls. It can also be equipped with mechanical agitation assemblies as required.