Every unit operation page is free to read.
No account, nothing to sign.
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. Every unit operation page is free, and so are three of the design sheets; the rest open with a subscription at SGD 6 per year. 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.
Iron and manganese out of groundwater — oxidant demand from the stoichiometry, catalytic media loading, the pH manganese actually needs, and the backwash that decides the design.
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.
Dissolved gas taken out through a membrane rather than a tower — Henry’s law sets the floor, the vacuum buys the driving force, and the pump is sized by the steam that comes with it.
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 — and the contact tank, where what matters is not the residual but how long the fastest water is held.
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.
What happens to the solids afterwards — sigma and the cut point for a decanter centrifuge, the cake filtration equation and the cycle it sets for a filter press, then the sticky phase a thermal dryer has to carry the cake through, and the greenhouse that does the same work on sunlight.
Not a unit operation — but almost all of them need it.
A dose is set in milligrams per litre of water and a pump is bought in litres per hour of solution, and between the two sit a strength and a specific gravity that are easy to apply upside down. Its own page, with the day tank and the polymer preparation unit on it, because the three answers depend on each other.
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.
The unit operation pages, the compatibility matrix and three full design sheets are free to everyone and stay that way. The rest of the design sheets are open to subscribers, and the workbook is the same 26 sheets as a file you own and can work offline. Either one pays for the same things — maintaining the calculators, adding unit operations, and checking the numbers against practice — and one per cent of both goes to carbon removal through Stripe Climate.