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Powder & Bulk Solids, June 2018

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www.PowderBulkSolids.com 27 J u n e 2 0 1 8 The closed or shrouded ro- tor has round end discs that are welded to the shaft and ends of the vanes. Looking at the ro- tor from the end of the shaft, you will not see the 'V' pockets but instead a round disc. The ends of the vanes are closed off. Unlike the open rotor, water poured into the top pocket is re- tained by the end discs. Which one is better, the open or closed rotor? As covered above, the rotary airlock pro- vides an air seal because of the tight tolerances between the rotor and housing. This "seal" is maximized with surface area between the rotor vanes and housing. The greater the surface area, the greater the seal. Since the open rotor vanes extend all the way to the end covers, it has more surface area than the closed rotor and provides the better air seal. However, the open rotor has its drawbacks as the material is in contact with the end cov- ers. For abrasive products this leads to increased wear and may shorten the life of the valve. In higher temperature applications, this adds to the tolerances that need to be carefully machined. Fine materials tend to leak out through the shaft seals if not properly maintained. Other mate- rials like thin flakes may become trapped between the sides of the rotor vanes and end cover faces which can lead to squealing or even stalling the valve. The closed rotor is primarily intended for gravity flow appli- cations or in lower pressure dif- ferential systems, but may also be used in high-pressure differ- entials when the rotary airlock is properly designed. When al- lowed, the closed end rotor is ideal for abrasive and high-tem- perature applications. In abra- sive applications, the product is kept away from the end covers where most wear takes place. In high-temperature situations, the gap between the end cover and rotor eliminates any expansion concerns, leaving only the di- ameter to be machined. Product also cannot become wedged between the sides of the rotor vanes and end cover faces, as the pockets are closed off by the end discs. Rotor Vane Design Rotor vanes may be either solid fixed blades welded to the shaft, or shorter blades with a bolt on adjustable tip. Fixed blades are typically thicker and more rigid than adjustable tips. As product can become trapped under the adjustable blades, fixed blades are preferred in sanitary type applications such as food and pharmaceutical. Some products are also sticky or sluggish, and the fixed blade rotor allows these products to more easily exit the pocket. Adjustable tips are utilized for applications in which special tips are required. Rotor tips can be either rigid or flexible, and are available for both open and closed end rotors. Rigid rotor tips should be utilized in all ap- plications where the pressure differential exceeds 2 psi. Rigid rotor tips include mild steel, stainless steel, bronze, and abra- sion-resistant steel. Bronzes tips are often requested when han- dling materials that are explo- sive or easily ignite. Abrasion- resistant tips are used obviously for abrasive materials to extend the life of the valve. Cablevey is a registered trademark of Intraco, Inc. 04/2018 (641) 673-8451 www.cablevey.com G e n t l e C l e a n R e l i a b l e C o n v e y i n g Decades of Global Experience 45 65 900 30,000 World-Wide Experts in Cable and Disc Conveying Solutions Years in Business Countries Served Products Moved Installations Horizontal system Rugged Design For Adverse Conditions Perfect for impact loading, wet materials, corrosive atmospheres and many other adverse operating situations, Carman Vibrating Feeders are built to deliver. Carman's solutions are custom designed for your application. Call us today at 800-456-7560 or email for a FREE brochure. info@carmanindustries.com • 800-456-7560 www.carmanindustries.com Feed & Quench. Vibrating Feeder Features Water Quench Pool With Steam Evacuation Hood Powder & Bulk Specialists Our industry leading quality can't be beat, and same goes for our delivery times! Couplings, Elbows, Fittings, Cyclones, Diverter Valves and Gates. We manufacture it all! # L o r e n z Q u a l i t y # L o r e n z C o n v e y i n g U S A 1 . 8 0 0 . 2 6 3 . 7 7 8 2 C A N A D A 1 . 8 0 0 . 2 6 3 . 1 9 4 2

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