Dust collection planner

Ducts — the system is a tree that starts at the collector. Each segment has a diameter, a length, a material (spiral or snap-lock metal, PVC drain pipe, wire-reinforced flex hose), its elbows (90° and 45°, with the centreline radius as R/D — 1.5 is a long sweep), blast gates, and how it joins the segment it feeds: a 45° or 30° wye, a 90° tee, or straight on (the next length of main, or a reducer). Put a machine on the last segment of a drop — usually the flex hose. The library gives the usual recommended airflow and port size for a table saw, jointer, planer, bandsaw, router table, shaper, CNC router, drum sander, lathe and others; change the figure to your machine’s own. Example shop loads a 2 hp cyclone with a 6″ main and five 4″ drops to start from.

Collector — pick a typical 1.5 or 2 hp single-stage, or a 1.5, 2 or 3 hp cyclone curve, or type in your collector’s published points (flow against static pressure). The typical curves are shapes, not any one product — use your own. The velocity targets are set here: 4000 fpm (20 m/s) in branches and 3500 fpm (18 m/s) in mains are the usual figures for keeping chips and fine dust airborne.

Results — tick the blast gates that are open. The tool builds the system curve for that set of gates (open branches balance to the same pressure where they meet, so each takes the flow its own resistance allows), crosses it with the fan curve, and gives the total flow, the pressure at the collector, and each segment’s flow, speed and losses. Worst machine alone and Worst two together pick the hardest cases. A table lists every machine with only its own gate open: what it wants, the static pressure its path needs at that flow, and what it gets. Warnings say where the air is too slow (dust settles and packs), where a machine is starved, where flex is too long, and where a main is smaller than a branch feeding it.

Plan — a schematic of the tree, with run lengths to scale, line width for diameter and colour for whether each run meets its speed target; click a run to edit it.

Method — friction per length for any flow and diameter in each material, and the sources.

Friction is Darcy–Weisbach with the Colebrook friction factor for each material’s roughness (ASHRAE: spiral metal 0.09 mm, PVC 0.03 mm, wire-reinforced flex 3 mm); at galvanised roughness it matches the ACGIH Industrial Ventilation empirical formula within a few per cent, which the tests check. Fittings are loss coefficients times the velocity pressure: smooth elbows by R/D from ASHRAE fitting CD3-1, ACGIH branch-entry losses for wyes and tees, a tenth of a velocity pressure for an open blast gate, and a hood or port loss at each machine (a plain duct end 0.93, flanged 0.49, a bell-mouth 0.04, a typical machine 1.0). Air is standard: 20 °C at sea level.

Not modelled: losses inside the collector beyond what its curve includes, a loaded filter, altitude, leaks past closed gates, and the small loss of a junction’s straight-through run.

For water and other fluids in pipes, see the fluid flow and pipe pressure drop calculator. The collector’s motor and its circuit belong in the shop power planner; compressed air has its own compressed air sizing tool. To place machines in the room first, draw the shop in the floor plan tool.

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