Support

Keep this site running.

This site has no adverts, no trackers and nothing to sell your attention to, which means a subscription is what pays for it. Twenty-five animated unit-operation pages, the material compatibility matrix and three full design sheets stay free to everyone and always will. The rest — every equation, design envelope and live calculator across 28 design sheets — opens for SGD 2 per year.

Subscribe — SGD 2 per year

Unlock every design sheet

Renews yearly, cancel whenever you like. Already subscribed? Sign in.

What it actually pays for

Small numbers, but they are real ones, and they are what a subscription covers.

Hosting and the domain. The bill that keeps the unit operation pages, the compatibility matrix and the free design sheets open to anyone who needs them — no adverts, and no selling of anybody's data.
Keeping the numbers current. Standards move, membrane products change, and correlations that were fine in 2015 are not always fine now. Checking that is unglamorous and it takes time.
New unit operations. Each page is a model, a schematic, an animation and the writing to explain it. They take days, not hours.
Corrections. If you find something wrong, I would rather hear about it and fix it than have it quietly mislead someone.
Carbon removal. One per cent of everything this site takes goes to Stripe Climate, which buys permanent removal of carbon already in the air rather than offsets against future emissions. It comes off revenue, not profit, so it is paid whether the year works out or not.

Or own the file — SGD 19.90

Buy the design workbook

The same 28 sheets as an Excel file you keep — works offline, prints, and is fit to go into a design submission. One payment, and every future version. SGD 19.90 until 31 December 2026; it doubles to SGD 39.90 on 1 January 2027. See what is in it.

Other ways to help

Tell me what is wrong. A correction is worth more to me than a payment. Send it here.
Tell someone it exists. Costs nothing and helps most.

What stays free, stays free. Every unit operation page, the compatibility matrix and three complete design sheets need no account and never will. A subscription opens every other sheet on the site, and nothing that is free today goes behind it later.