1. Empty the system of the production resin, and make sure the feed areas are clean.
  2. If possible, and safe, raise heats in all zones after the screw and barrel to at least 230⁰C (450⁰F). Best results will be obtained at 260⁰C to 315⁰C (500⁰F to 600⁰F). Temperatures of outboard heads (in multiple head setups) should be 30⁰C (50⁰F) hotter than inboard heads. Do not exceed 360°C (680°F). Do not use ASACLEAN NCF for extrusion blow molding.

If purging a heat sensitive resin, do not exceed the safe processing temperature of the material. This purge procedure may need to be repeated at elevated temperatures to remove all contamination.

  1. Manually clean and cap all barrel vents, and increase temperatures in the decompression zones by 15⁰C (25⁰F), and make sure the feed areas are clean.
  2. Flush the machine by running 1-4 system volumes of clean, natural blow molding grade HDPE. It is best to use an HDPE that is stiffer than the production resin.
  3. Empty the system of the flush resin, and add ASACLEAN chemical grade at normal screw speed until the purge extrudes uniformly from the head(s). If using accumulators, increase the setpoints by 10% and cycle on automatic 2 to 4 times to ensure complete filling.
  4. Turn the screw at minimum controllable rpm for a 30 minute heat soak. ASACLEAN chemical grade is heat activated, so expansion will occur during the heat soak. For reciprocating screws, stop the screw during the soak phase, and take a shot every 5 minutes to ensure the head stays full.
  5. Empty the screw and barrel.
  6. If the last of the purge carries contamination, repeat steps 5-7.
  7. Wait 5 minutes with an empty barrel for the ASACLEAN chemical grade residue to break down.
  8. Change temperatures to the profile required for the next material.
  9. When safe, displace the ASACLEAN chemical grade with the next resin.
  10. Begin production under normal processing conditions.

N Series Chemical Grade Purging Procedures