Extrusion International 6-2016

33 Extrusion International 6/2016 Variable-Speed Capability Gives Users New Options The patent-pending R-PRO™ dense-phase vacuum-conveying system developed by Conair to minimize pellet fracturing, “angel hair” and equipment wear caused by conventional dilute- phase conveying, will make its first appearance at a European tradeshow when Conair will present at K 2016 the results of R&D efforts aimed at taking advantage of the fact that the system can be “tuned” to match material speed to application requirements and the characteristics of the material being conveyed. Other innovations on display will include a new FLX-128 Plus conveying control, which now can be set up to operate the R-PRO system, a new Mobile Drying/Conveying (MDC) system with standard color touchscreen control interface, and several examples of equipment from Conair’s new MedLine ® range of clean-room- ready auxiliaries. R-PRO test apparatus installed at Conair Technical Center In slow-speed, dense-phase conveying, pellets move in compact slugs of material at speeds between 300 ft/min (91.5 m/min) up to 1200 ft/min (366 m/min). In conven- tional high-speed conveying, 4500 ft/min (1372 m/min) is a typical low speed and air speeds up to 6000 ft/minute (829 m/min) are not uncommon. Response to this innovation has been very positive, espe- cially since conveying throughput and distances are com- parable to high-speed systems. In addition, since R-PRO uses standard deep-vacuum pumps, conveying tubes and material receivers, the system costs only a little more than conventional systems and can be easily retrofitted to ex- isting systems. The variable-speed capabilities of R-PRO now give proces- sors the flexibility to tune the system to their exact needs. For highly abrasive glass- and mineral-filled materials, Brewster says, the slowest material speeds are “absolute- ly the best.” However, he continues, “we are finding that When the Conair R-PRO ® [Resin-PROtection] conveying system was first introduced a year ago, the focus was on slow-speed dense-phase conveying, which eliminates pellet fracturing, dust, “angel hair,” equipment wear and other problems caused by conventional high-speed vacuum conveying. However, Doug Brewster, Conveying Product Manager, and the inventor of the system, says R PRO is not only capable of running at low speeds. It can also operate in the more conventional dilute phase, with individual pellets fully suspended in the high-speed air… or at any speed in between. He reports that, as material speed increases, there is a gradual transition from dense phase to dilute phase, and “we have found we can con- trol that transition very effectively and run right on the edge in a sort of mixed pulse phase. We think we can use this for higher-volume unloading where more airflow may be desirable but truly high-speed operation is not necessary or desirable.” K 2016 REVIEW