How do I purge PUR from my melter?
At processing temperature, drain the remaining PUR, load a PUR purge (Cattie PUR-Purge-8530, run at 250 to 350°F, or 9006 PUR purge flake), circulate it, and push it through the hoses and nozzle until it comes out clean. For a shutdown, leave the purge in the unit. At startup, flush with fresh PUR until no purge shows. Never run production on purge.
PUR cures with moisture. It will cure in the tank, hoses and nozzle if you leave it, and you typically must scrape out cured PUR. A regular purge routine is what keeps a PUR line running.
Contains reactive isocyanate. Read the SDS before use; use ventilation and protective gear; hot melt can cause burns. Call us for data sheets
Purge steps
- Keep the unit at processing temperature. Drop pump pressure to zero.
- Drain the remaining PUR at temperature, using non-metal tools only. Hot material: wear heat-resistant gloves and eye protection.
- Load PUR purge: PUR-Purge-8530 (runs at 250–350°F) or 9006 PUR purge flake.
- Circulate typically about 15 to 30 minutes at processing temperature. Allow longer if gel or char is present. Follow the purge product’s instructions.
- Push purge through the hoses and nozzle until it comes out, not just the tank. Change any inline filters.
- For a shutdown, stop here and leave the purge in the unit.
- At startup, flush with a small charge of fresh PUR until no purge shows, and discard the first few shots. Then start production.
When to purge
| Situation | What to do |
|---|---|
| End of shift or weekend | Purge and leave the purge in the unit. Flush with fresh PUR at startup. |
| Before a run on a cold unit | Purge, flush with fresh PUR, then start production. |
| Changing to EVA or another hot melt | Purge PUR fully first, then follow your equipment maker’s changeover steps. |
| Signs of gel or rising viscosity | Purge now, and allow a longer circulation. |
Small binders
On tabletop and single-clamp binders, load PUR-Purge-8530 or 9006 purge flake, run it through, then shut down or restart, following your binder maker’s procedure. Cattie’s 100 g foil packs help you load only what the run needs. See how to run PUR on a small binder.
Always follow your equipment maker’s procedure for your melt unit.
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Related
PUR hot melt · Edgebanding adhesives · PUR safe handling FAQ · How to handle reactive hot melt · How to clean a hot melt system
PUR purge FAQ
What does Cattie sell to purge PUR?
PUR-Purge-8530 purge compound, run at 250 to 350°F, and 9006 PUR purge flake.
How long should I circulate purge?
Typically about 15 to 30 minutes at processing temperature, longer if gel or char is present. Follow the purge product’s instructions.
Can I leave purge in the melter over a weekend?
Yes. Purge and leave the purge in the unit at shutdown, then flush with fresh PUR at startup until no purge shows. Never run production on purge.
What if PUR has already cured in the tank?
Cured PUR does not remelt and can only be removed mechanically, by scraping. Purging on schedule prevents it. Call 800-249-0337 if you are dealing with a cured unit.
Can I switch back to EVA after PUR?
Yes, many shops run both. Purge the PUR fully first, then follow your equipment maker’s changeover steps.
