Flow, viscosity and pressure drop in filter selection
Learn why connection size and water-flow ratings are insufficient, and how flux, clean/loaded pressure drop, batch duty and circuit margins interact.
Flow and connection size are different inputs
Flow measures volume per time; connection size describes a fitting. The same fitting can serve different media areas and resistances.
Use Q=V/t for average batch demand and identify actual branch flow in circulation. Pump nameplate or total system flow may differ where bypasses and returns exist.
Flux and viscosity
Flux J=Q/A relates throughput to effective area. In an ideal linear clean-medium regime, Δp≈μRJ illustrates viscosity and flux effects, with R as medium resistance.
Real housings, valves, supports and non-Newtonian fluids add complexity. Use this as a trend model and use applicable curves or trials for sizing.
Operating, clean and replacement pressures
Operating pressure concerns containment; differential pressure is the inlet/outlet difference. Clean differential pressure describes initial resistance, while loaded resistance also reflects deposits.
Replacement must account for equipment limits, minimum flow and quality. A quality limit may arrive before a pressure limit. Follow the established isolation procedure for servicing.
Read conditions before the curve
Check fluid, temperature, element count, length and rating behind a curve. Water data need an applicable correction or trial for viscous service. Housing-only loss is not the complete filter loss.
Log flow, temperature and pressure together. Lower pump speed can lower pressure drop without removing contamination.
Example: batch demand versus equipment capability
Hypothetical example: 5 m³ in one hour requires 5 m³/h; in 45 minutes it requires about 6.67 m³/h. This changes production demand, not guaranteed equipment capacity.
Then assess fluid, element and circuit resistance at the target flow, including loaded margin. These are illustrative calculations, not product measurements.
References
Applying these principles to your production line? Share the fluid, throughput, operating conditions and current equipment to discuss a filtration configuration.