Extrusion FAQ: Can I Run Purge Through Melt Pumps & Static Mixers?

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Here is a twin screw extruder from our friends at Leistritz

Many extrusion processors ask us whether or not you can run purging compounds through melt pumps and static mixers.

Yes. You can run purging compounds through melt pumps and static mixers.  But some kinds of purging compounds are a better choice than others. Before we share our recommendations, let's look at what each component does.

A melt pump's main purpose is to control output to the die. The melt pump compensates for things such as erratic temperature control, feed, interruptions, changes in the polymer mix and surging due to screw design.

Static mixers help with homogenization, uniform viscosity/density, enhance mixing of colors and additives, and correct inconsistencies in the polymer melt prior to the die.

Both components can be difficult to clean when performing color changes, material changes, or when you have carbon contamination. The trick is to be able to both clean these components effectively AND be able to displace the purge material quickly once the purge process is complete.

While mechanical and chemical purging compounds each have benefits, a high quality chemical purge like Asaclean's NCR Grade is best suited for this application. It has the advantage of a foaming action which will reach negative flow areas and dead spots within the components.

Chemical purges also create steam which aids in the cleaning process, and are engineered to a viscosity compatible with that of the resin being removed. In the case of Asaclean NCR or NCF Grades, particle size of the product in it’s melted state is sub-micron and WILL NOT have an adverse effect on either component. 

These are some of the reasons why you can run Asaclean chemical purges through melt pumps and static mixers.     

Ready to reduce your production downtime to protect your profits? Learn more about how purging compounds and process efficiency work in tandem.

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Topics: Troubleshooting, Plastics Processing, Melt Pumps, Extrusion, Plastics Production, carbon contamination, reduce downtime, extrusion troubleshooting, plastics manufacturing, black specs, preventative purging, Cost savings, static mixers

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