Equipment for Immersion Systems

Tanks for cleaning solution should be constructed of hot-rolled steel. Depending on tank capacity , steel gage requirements are as follows:

All seams should be penetration welded and dye checked for leaks. Channel or angle iron reinforcements should be welded wherever they are required for strength or rigidity. All tanks should be built up on a frame so they can be insulated underneath and so they can be picked up. Tanks should have a minimum of 25 mm (1 in.) of insulation with light-gage, cold-rolled steel cover panels for energy efficiency.

Tanks can be heated with steam or immersion electric elements. Gas burners are not recommended because of potential flash. Where steam is used, coils are preferred to an open line. Condensate from an open line will dilute the solution. Coils must, of course, be fabricated of a substance compatible with the solution to be heated. Iron or steel tubing is recommended for alkaline solutions, while acid-resistant metals, graphite, and impervious carbon are recommended for acidic solutions. The steam coil length depends on the type of tank, the coil diameter (not less than 1 in.), the steam pressure available, and the speed with which the solution is expected to heat to optimum temperature. Commercially available plate coils are most efficient.

Electricity as a tank heating method is most efficiently applied by means of electrical resistance elements, encased in protective jackets and immersed within the solution. Where possible, the heat-transmitting medium should be readily removable from the tank. It should not be located on the tank bottom where scale or sludge can reduce its efficiency or where it could be damaged when sludge is shoveled out.

Emulsion solutions with pH > 8 will provide rust protection so the wash tanks can be carbon steel. Alkaline wash tanks can also be carbon steel. Rinse tanks should be stainless steel.

Provision of agitation is important. Agitation keeps bringing fresh solution into contact with the work and introduces a degree of physical force to supplement chemical activity. The result is faster cleaning.

Draining is an important consideration. An overflow surface drain permits surface grease and oil to be skimmed off, preventing rapid solution contamination. A bottom drain is also necessary, to discard solution.

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