ASACLEAN EXTRUSION PURGING INSTRUCTIONS for Transitions from High Heat Resins to Other Resins Above 680°F (360°C) to below 570°F (300°C)
Screens and dies may be left in place for purging with the ASACLEAN SX. Special procedures may be required to effectively clean extruders with vented barrels. If possible plug the vents. If the vents cannot be plugged, contact Technical Service to discuss the most appropriate options.
- Upon completion of the production run, extrude the high heat resin from the machine, emptying the barrel. Clean the hopper and feed throat.
- Feed about 1 barrel capacity of the ASACLEAN SX into the hopper.
- Begin to drop the temperatures in the extruder to below 700°F (370°C) while purging with the ASACLEAN SX. ASACLEAN SX should not be left at temperatures above 700°F for more than 30 minutes as decomposition may occur.
- Start purging at slow screw speed. After the ASACLEAN SX starts coming out from the extruder, increase the screw speed to a safe moderate level. Several times during purging, stop the screw and allow the ASACLEAN to sit for about 30 seconds. Resume the screw rotation up to a safe moderate level. If resin contamination is still visible in the purge piles, repeat steps 2-4 until clean.
- When all temperatures are below 700°F and the purge pile appears clean, stop the screw rotation. Leave the barrel full of ASACLEAN SX to prevent oxygen from entering the barrel. Oxygen will accelerate material decomposition and carbon formation.
- Continue to drop all temperatures to between 600°F – 620°F (315°C – 325°C). The temperatures should not be allowed to drop below 570°F (300°C) with ASACLEAN SX in the barrel. Overloading of the screw may occur at temperatures below 570°F when screw rotation resumes.
- Using maximum safe screw speed, run all of the ASACLEAN SX from the extruder. Begin feeding the lower-temperature ASACLEAN grade and drop the temperature settings to the processing temperature of the lower-heat resin. After all of the ASACLEAN SX has been displaced by the lower-temperature ASACLEAN grade, leave the barrel full of the lower-temperature grade and stop the screw. The lower-temperature grade should have a slightly different appearance than the ASACLEAN SX. The lower-temperature grade should not be left at temperatures above 570°F for more than 30 minutes as decomposition may occur. If it takes longer than 30 minutes to get to the required lower temperature, run a fresh barrel of ASACLEAN and continue dropping temperatures.
- When the temperature drops into the processing range of the lower-heat resin, empty the ASACLEAN from the barrel. Then start feeding the next resin to be processed.|
- Displace the ASACLEAN with the next resin following the standard purging procedure.
- After all of the ASACLEAN has been displaced, begin production using normal processing conditions for the resin.