For the main line and for EACH drop, the tool finds the smallest EQOfluids diameter (DN20→160) that meets TWO criteria at once: pressure drop (≤ your allowable drop — the primary criterion of every manufacturer) AND an air-velocity guard-rail ≤ 30 ft/s (~9 m/s), CAGI ch.4’s general-distribution target (the ideal for a main would be ≤ 20 ft/s [~6 m/s] against water carryover past drip legs, but that oversizes; we use 30 ft/s, the acceptable target).
Drop is computed with Colebrook over the developed length + the equivalent length of fittings (Le/D). OPEN LINE: the full flow travels the whole length. LOOP (CAGI ½ rule): air reaches the point from both sides, so the tool computes over ½ length (drop ≈ half, CAGI ch.4) at full flow → a smaller diameter than an open line. CAGI sets no “Q/2”; velocity is evaluated at full flow (upper bound). Each drop is sized on its own tool flow.
Indicative estimate (CAD, before taxes). Series 89 manifold (valve + drain built in), takeoff by saddle branch, supports per max spacing by Ø (min. 2/pipe), isolation valve at the head, end plug on open lines. To be confirmed — the quote prevails.
