Abrasive purge

Materials of construction. The instrument must withstand the process conditions to which it is exposed. This encompasses considerations such as operating temperatures, operating pressures, corrosion, and abrasion. For some applications, seals or purges may be necessary. 

PE-based compounds usually contain abrasive and release agents. They are used to purge the softer TPs (polyolefins, styrenes, some PVCs, etc.). With extruders, many of the requirements/restrictions do not apply. 

Both large and small particles of dust can be a concern in process installations because small particles can coat optics, thus reducing throughput, and large particles may be abrasive. Thus, it is important that the analyzer be appropriately housed. Outdoor installations normally have to be sealed for other reasons, which effectively obviates the dust problem. In the laboratory, plant floor, or control room, a continuous supply of air is sometimes used to purge the analyzer enclosure. 

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