What matters in the process
This difference affects cake handling, equipment layout and the questions to ask during trials. A bag-pulling sequence should demonstrate how much heel remains and how quickly the cloth returns to a usable condition. An inverting filter should demonstrate repeatable release, cloth movement, discharge containment and product handling without a scraper. Both depend on cloth selection and the material sticking to it.
A practical example
If a valuable product adheres strongly to the cloth, weighing only the main discharge can overstate recovery. Weigh the discharged cake, retained solids and solids in the liquid streams over repeated cycles. Inspect the filter medium after several batches instead of judging only the first clean-cloth cycle.
What to check or specify
- Define permitted residual product and cross-contamination risk.
- Measure discharge time and recovered mass.
- Evaluate crystal attrition and receiving-hopper behaviour.
- Check cloth replacement, service access and cleaning.
Turn the result into a decision
Do not translate the PLD and FW mechanisms into the same product name in an RFQ. State whether the priority is heel removal after scraping, avoidance of scraping, cleaning between batches or containment. Those objectives guide the comparison more effectively than a generic recovery claim.
Equipment context: supplied HUADA English catalogue, PDF pages 23–25, 34. Numerical examples are illustrative calculations. Application guidance must be confirmed for the actual material and selected equipment.
