| 摘要 |
A tank arrangement particularly adapted for processing parts in chemical milling operations, especially for circulation of water-base maskant fluid. The system includes a tank containing up-flow and down-flow draft tubes, each containing a low speed, high volumetric displacement impeller which minimizes shear stresses imparted on the maskant liquid. The up-flow tube provides circulation and establishes rapid surface flow velocities to prevent congealing of maskant liquid and the down-flow tube provides localized circulation and produces a fluid elevation change. A weir is provided at the top of each of the draft tubes, the use of which combined with the low speed impellers break up and disperse entrained air. The draft tubes include baffle plates suitably located to prevent the formation of vortices above, within and below the tubes. Adjustable fluid flow deflector plates are provided adjacent to the lower ends of the draft tubes to eliminate "dead spots" in the tank work zone. The tank is provided with rounded bottom portions at the opposite ends thereof to reduce turbulence and improve fluid flow in the lower regions of the tank. The tank design provides for containment, efficient agitation and circulation of water-base maskant fluid while preventing congealing thereof and minimizing mechanical energy transfer to the fluid.
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