CIP Flow & Velocity Calculator (5 ft/s Rule, ASME BPE) — Sample Report

1 · Design inputs

2.0 in ID transfer line; find the CIP flow for 5 ft/s, then check a skid that can only deliver 60 gpm.

2 · Method

Q (gpm) = 2.448 · v (ft/s) · ID² (in)

v = Q / (2.448 · ID²)

Both directions are the same continuity relation Q = v·A for a round section, A = π/4·ID². The 2.448 coefficient is the exact unit-conversion constant — 448.831 gpm per ft³/s times π/4, divided by 144 in² per ft² — not an empirical factor. In sizing mode the calculator multiplies the target velocity (5 ft/s by default, overridable) by 2.448·ID² for the required flow, reported in gpm and L/min. In check mode, an entered supply flow is inverted through the same relation for the achieved velocity in ft/s and m/s; achieved at or above target is PASS, below is FAIL with the shortfall stated. Because ID enters squared, required flow grows steeply with line size — which is why the largest ID in the circuit governs the skid. A line ID under 1.5 in additionally raises the SD-6.3.5.2.1 branch/short-outlet drainability advisory, pointing you at the dead-leg and slope checks for that run. Metric equivalents are computed on every run — L/min from gpm and m/s from ft/s — so a 1.5 m/s specification can be checked without hand conversion, and both calculation directions are locked as separate fixture cases in the release gate.

3 · Calculation

1. Required flow: Q = 2.448·5·2² = 2.448·5·4 = 48.96 gpm (185.3 L/min).
2. Check mode: v = 60 / (2.448·4) = 60 / 9.792 = 6.13 ft/s (1.87 m/s) ≥ 5 → PASS.

4 · Results PASS

5 · Verification statement

The result values above are locked as fixture cip-velocity.json, case “2 in line, 5 ft/s target -> required flow”, tolerance 0.01, in the calc-core continuous verification gate (see https://pipingtoolset.com/trust/validation.html). Allowable-stress and factor data are user-supplied inputs; citations: ASME BPE — SD-6.3.5.2.1, CIP line velocity practice.