Plate Settler Surface Loading
The Governing Sizing Parameter
Surface loading rate (SLR), also called overflow rate, is the flow divided by projected settling area. It is the single most important number in plate settler sizing.
Plate Settler Surface Loading
Surface loading rate expresses how much flow each square metre of projected settling area must handle, in metres per hour. Any particle whose settling velocity exceeds the SLR will be captured; particles slower than the SLR risk carryover.
Selecting the SLR is an engineering judgement based on particle characteristics, coagulation, temperature and the effluent target. Conservative rates give robust effluent quality; aggressive rates minimise footprint and cost but leave less margin.
R+F sizes systems within proven ranges for each application and validates the selection against your water quality data before quoting.
SLR = Q / A_projectedSLR in m/h; Q in m³/h; A_projected = total projected (horizontal) settling area in m².
Typical SLR Ranges
Free Sizing Check
Try the interactive Plate Settler Sizing Calculator, or send us your flow and water-quality data for a preliminary sizing at no cost.
Key Considerations
Coagulation Helps
Chemical conditioning increases floc settling velocity, permitting higher SLR.
Cold Water Penalty
At low temperatures reduce the SLR to compensate for higher viscosity.
Polishing Duty
For very low effluent turbidity, select an SLR at the low end of the range.
Request an Engineering Assessment
Our engineers will review your application, flow rates, and water quality data to recommend the optimal plate settler configuration.