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While PATT Filtration prides itself on its range of screenchangers handling the broadest range of polymers, filtration problems often demand something more than our standard product line. Our custom engineering services offer far more than the "Off the Shelf" screenchanger. Our flexibility as a small company enables quick response to customer problems and service requirements. Our screenchangers use custom-fit wire mesh screen packs. Made from a variety of square mesh and dutch weaves, they can be customized to fit your needs, whether you run LLDPE, PVC, ABS, HDPE, PP, rubber or a special blend proper to your production. The pack combinations can come in stainless or plain steel and are designed for all of our PATT Filtration screenchanger sizes. Mesh sizes from 20 to 400 guarantee various level of filtration precision. Packs are custom tailored mesh combinations specific to your production needs. Clockwise from the right: E-size, D-size, C-size, B-size and A-size screens, various meshes. PATT Filtration custom tailors continuous screenchanger equipment to filter any engineering polymer with pressures up to 12,000 psi and temperatures up to 650F. |
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The ROTARY IIITM Constant Pressure Drop Continuous screenchanger series uses a rheologically correct flow channel design and microprocessor controls to stabilize process conditions and maintain constant pressure to improve overall production conditions. PATT’s Rotary III handles the broadest range of polymers of all the screenchangers on the market. Capacities range from 50 to 30000 lb/h. It is leak-proof and maintenance free — there are no seals to replace. The melt flows through a revolving disk with a fixed number of either integral fixed or removable breaker plates with screenchanger cavities, arranged in a circular shape and separated by curved ribs. Even if those narrow webs pass through the flow channel their kidney shape and the optimized melt channel will insure maximized available screen area and undisturbed melt flow. Upon signal from an alarm or observation of pressure sensors, an operator initiates the screenchanger cycle. An hydraulic cylinder pushes on the recently cleaned block which in turn pushes the standby and active block a distance down the track. The distance these blocks travel is just enough for the heated standby block to enter the melt stream. The active block is still mostly in the melt stream and remains there until the heated standby block is filled with polymer. There usually is a port venting the heated standby block to atmosphere. |
Conveying screen changers are those types of screenchangers that bring screen packs or screen belts into through and out of the melt flow. These types of screenchangers are continuous because they allow polymer to flow while screen media is replaced. This variety of belt type screenchanger uses a positive tow rather than polymer pressure to move the screen belt. While these type screenchangers are continuous because they change screens without shutting off the polymer flow, they respond to pressure increases in order to effect screen changes. Leakage is a problem with almost any screenchanger. In use they are usually torqued up to prevent leaks and then backed off when a screen change is needed. Rotary screenchangers have a huge sealing surface and leakage is not a common problem. The body blocks and the faces of the disc are superbly machined and polished to mirror like finishes. Using very precise torquing techniques, manufacturers squeeze the disc to unbelievable values. The common way to deal with these problems is to run on a heavier spec to compensate for any dimension variances between screen changes. Imagine the savings you could realize by running at the low end of your specification requirement. Our rotary screenchanger will give you that capability. Some of our customers report up to 7% material savings after switching from a slide-plate system to our rotary screen changer. |
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