The PureFlo filterless vacuum receiver introduced by Piovan helps reduce operating costs, eliminate downtime and maintenance problems, and improve conveying efficiency. PureFlo has proven its worth in a number of successful installations and has attracted sufficient processor interest to justify its own product-specific online “minisite”, according to Piovan of Italy.
The device has no filter on the receiver. PureFlo eliminates gradual loss of conveying efficiency as the filter accumulates dust, which is collected at the central filter station. Also eliminated are problems of filter “blinding” by “angel hair,” clumps of which can fall off the filter or screen and cause problems when they enter the process. There is also no need for expensive compressed air for filter cleaning at the receiver.
                                     Source: pureflo.piovan.com
Abrasive wear is a growing problem, due to increasing use of glass and other abrasive fillers. Wear is caused by pellets entering the receiver at high velocity—up to 25 m/sec, or 5000 ft/min. Wear can cause not only maintenance problems, but also contamination, as metal particles can migrate into finished parts. Customers are replacing existing receivers where the walls are wearing through due to the abrasive impact of the material, according to Chuck Thiele of Vactec LLC, Kalamazoo, Mich., who developed the device. This product simply puts aside many of the issues that have plagued vacuum conveying systems for years. It’s easy to clean, simple, and trouble-free.
The difference with PureFlo is that material enters the receiver through an abrasion-resistant material inlet and a Vactec-developed RaBend (right-angle bend) elbow. Velocity-reducing elbow inside the receiver cuts wear and ensures air separation from material. The elbow absorbs the material impact and dissipates the kinetic energy of the material, so the material drops softly into the receiver while conveying air (also now at low velocity) exhausts through a ring vent. This creates an exit air velocity of about 200 ft/min (1 m/sec), which is much too low to pick up resin material. Thiele says this achieves nearly 100% separation efficiency at only slightly higher cost than a filter receiver. PureFlo can be applied to new and existing systems ranging in size from 1.5 to 6 in. diam.
One injection molder recently installed PureFlo receivers on two new presses. Bemis Manufacturing Co., Sheboygan Falls, Wis., had used filterless receivers on its existing presses, and some had worn out after 20 years’ use. Alan Hendrickson, Bemis senior manufacturing engineer, said that they liked that it was simple and easy to clean, with no place to trap material. Especially convenient is having no hose connections on the receiver cover, so they can lift it right off for cleaning. The receivers are said to be operating with better than 99.99% efficiency.