Practical sizing calculators for first-pass process design — put in the duty, get a number you can defend, with the envelope industry practice actually accepts printed next to it. Free to use and free to pass on. If something here is wrong, or a unit operation is missing, email me or use the Q&A box — corrections get fixed and credited on the sheet.
Every section, with what it sizes and how many sheets it holds.
Circular and rectangular clarifiers, dissolved air flotation, lamella packs and graded media filtration — overflow rate, scour and backwash.
Carbon bed contact time, usage rate and service life; resin volume, service flow rate, regenerant demand and cycle availability.
Microfiltration through to reverse osmosis — design flux, transmembrane pressure, array staging, tail-element scour and specific energy.
Continuous deionisation: feed conductivity equivalent, ionic load, Faraday current, stack voltage — and the feed specification that governs whether it works at all.
UV dose from fluence rate and residence time, the Beer–Lambert profile across the annulus, and the validated equivalent you can actually quote.
Heat exchanger duty from the energy balance, log mean temperature difference with its correction factor, and the fouled area you specify the unit on.
Velocity gradient, Camp number and impeller power for mixing and flocculation; reagent demand, dosing pump duty and staging for pH correction.
Not a unit operation — but everything above depends on it.
Nothing is separated or transformed in a pipe or a pump. Hydraulics is the conveyance between the unit operations, and it is where a sound sizing calculation is most often undone — a line one size too small, or a suction that cavitates.
Every sheet here stays free. The workbook is what pays for keeping the calculators maintained, adding more unit operations, and checking the numbers against practice.