Section 18 · Design & Build

Sizing calculator

Enter four numbers from your site and get the first-pass design: delivered water, drive-pipe size and length, power balance — plus a few honest warnings.

Your site

Source flow you can spare (Q)

Fall — source surface to ram (H)

Lift — ram to delivery point (h)

Expected energy efficiency (η) — 60% is a fair field value 60%

Try:

First-pass design

Delivered flow q—

Per day, running 24/7—

Wasted flow (the fuel)—

Lift ratio h/H——

Suggested drive pipe—

Drive pipe length (3–7 × H)—

Input water power—

Output water power—

Total through the ram—

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Taking this to the hardware store?

Print the one-page cheat sheet — every formula and rule of thumb from this site, sized for a clipboard.

How this works

The calculator applies the standard first-order relations from the Physics page:

q = η · Q · H / h · P_in = ρg·Q·H · P_out = ρg·q·h · D = √(4Q / (π·v)), v = 1.5 m/s

Drive pipe length is suggested as the classic 3–7 × H band; lift-ratio verdicts use the 6:1 / 10:1 thresholds.

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First-pass means first-pass

Real rams lose a few percent to friction, valve timing, temperature and wear, and commercial manufacturers publish measured capacity tables that differ from theory. Treat these numbers as a feasibility check and starting point — then tune on site (see tuning).