Conservation of Solvent

The maintenance of an adequate volume of solvent in the degreasing tank is important to the efficiency of the degreasing process. Loss of solvent can be minimized by observing the following precautions:

• The vapor degreaser wall (freeboard) should extend above the top of the vapor zone by at least 75% of the width of the degreaser.

• The degreaser should not be located in an area subject to drafts from doors, windows, or fans.

• Dragout loss should be minimized by proper drainage. Specially designed racks or rotating baskets made from wire mesh or round stock are effective.

• Where the work is small and tightly packed into a basket, the basket should be allowed to drain in the vapor area before being removed from the degreaser.

• Spraying, when required, should be held to a minimum and performed well below the vapor level.

• Work should remain in the vapor until all condensation has ceased.

• Work should not be rapidly introduced into or withdrawn from the degreaser. Vertical speed of mechanical handling equipment should not exceed about 3.4 m/min (11 ft/min).

• The degreaser should be covered when not in use. Well-designed manually operated degreasers are provided with suitable covers; conveyorized degreasers are provided with hoods.

• Plumbing, cleanout ports, valves, and pumps should be checked periodically for solvent leakage.

• Introduction of moisture into the degreaser should be avoided. Except in special situations, work that has been wetted in a previous process should not be brought into the degreaser until it is completely dry.

• Work loads should not occupy more than 50% of the open cross-sectional area of the degreasing tank. When work is lowered into the vapors, it absorbs the heat in the vapors, causing the vapor level to drop. Work load should be sized to minimize this fluctuation of the vapor level.

• Porous or absorbent materials should not be degreased.

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