Coatings, as we know, typically contain a broad range of dispersed solids, ranging from additives to pigments and various extender pigments.

These solid materials are often used in the manufacturing process as fine powders. After their addition to the processing vessel, powerful high-speed dispersers are used to disperse the pigments into the vehicle. Obviously, the solids entry port must be closed securely or there would be splashing, and volatile materials could exit into the room. With multiple processing vessels this would not only create a hazardous situation, but also an unpleasant and dirty working environment that could lead to cross contamination.

Lockwood Greene was the engineer for a Degussa Huls America plant in Cincinnati, Ohio. The plant manufactures color-tinting concentrates. Lockwood Greene selected Roto-Disc® valves for this application. The simple internals allow for easy cleaning between batches. There is virtually no place for material to hide from the spray ball cleaning performed from below.

In operation, a funnel chute is placed over the Roto-Disc valve and clamped to its flange. Solids are weighed and placed in the funnel. Care in weighing and verifying these ingredients is critical to quality control. When the appropriate time in the process comes, the valve is opened. The entire dry product gets into the process because there is no hold up in these valves. The 8" valve has a 10" outlet, which assures an expanded flow area. The dome is wiped clean of product dust as it closes. The bottom of the dome is vertically down to allow any product to fall away. Over a dozen such valves have been in operation since 1998 at this facility and have had little maintenance.

For more information, contact Roto-Disc Co., 4612 Kellogg Ave., Cincinnati, OH 45226; phone 513/871.2600; e-mail, or visit