Maag — a Switzerland-based provider of gear pumps, filtration systems and pelletizers for the
plastics, chemicals, petrochemical and food industries — reports its state-of-the-art screen change
filter technology is being utilized at the world’s largest polyethylene terephthalate (PET)
production line, operated by a customer in the Middle East.
The continuous screen changers were installed as part of the customer’s expansion project,
which was completed in 2012 and increased its manufacturing capacity of PET bottle-grade resin by
half a million tons annually. Maag previously had provided the plant’s production line with a
complete range of melt pump equipment based on the MTR® (Melt-To-Resin) process designed by
Germany-based Uhde Inventa-Fischer. For the expansion, Maag developed the customized filtration
unit in cooperation with Uhde Inventa-Fischer.
According to Maag, the screen changers have a small footprint and feature patent-pending
arched filters that offer a very low melt resistance time, particularly in high-viscosity resin
applications. In contrast to Maag’s supersized screen changers equipped with candle filters, the
arched filters utilize disposable one-way filters, eliminating the process of cleaning the candle
filter bundle to determine a filter’s usability.
“Though duplex and simplex filters are still widely used, piston-based screen-changers are a
natural, cost effective addition to Maag’s portfolio, and they meet the increasingly technical
demands of our customers,” said Ueli Thürig, CEO, Maag. “As for the adoption of arched screens it
allows manufacturers to dedicate 75 percent of the surface of the cylinder to filtration. Finally,
and contrary to traditional breaker plates facing each other, our very smart design also permits
straight pump connections that reduce the investment further with no need for additional pipe
Maag reports that changeovers take less than 10 minutes, require only one operator, and do
not require the use of cranes or complex tools. The screen changers may be constructed of woven
wire mesh or fiber metal mesh, depending on the melt contamination.
March 12, 2013