Process reasoning
Fine particles, precipitated salts, sticky components or biological deposits can restrict the filter medium. A retained heel adds another flow resistance and can change with repeated compression. The feed itself may have acquired a higher fines fraction or viscosity. Compare cycle-stage data and inspect the filter only using the approved isolated maintenance procedure. Cloth permeability alone is not a measure of performance when covered by the actual cake.
ILLUSTRATIVE EXAMPLE
Apply the reasoning
Suppose illustrative filtration time rises from 8 to 13 minutes over a campaign while the wash and spin stages remain unchanged. Record the feed distribution, solids loading and temperature before attributing the rise to cloth wear. A documented clean-media reference and an approved heel-removal comparison can help separate causes. Replacing cloth without understanding the deposit may simply repeat the same decline.
What to record
| Item | Basis to document |
|---|---|
| Feed change | Particle-size distribution, viscosity and concentration |
| Media condition | Deposits, damage, sealing and compatibility |
| Heel history | Number of cycles, retained mass and regeneration sequence |
| Performance trend | Time for each stage at comparable solids loading |
Review checklist
- Compare normal and deteriorated operation on a common feed basis.
- Check the washing and cleaning liquids for precipitation risks.
- Preserve a sample of the deposit for analysis.
- Follow the supplier’s access, cleaning and replacement instructions.
Your next decision
Specify an evidence-based media and heel-management plan during selection. PLD bag pulling, siphon-related heel treatment and cloth inversion are distinct concepts whose suitability depends on the actual cake. Ask for repeat-cycle trials and the expected consumable requirements, with cleaning compatibility and any practical limitations documented.