Wind Systems · Volume 7
Wind Systems — Vol 07: Reference & Cheatsheet
This final volume consolidates the reference apparatus of the whole Wind Systems series into one place to keep at the bench: the pressure-unit conversion table (consistent with Vols 01 and 04), a one-page recap of the wind chain, a full glossary of the terms the series has used, a formula and quick-reference card, a section-level cross-index to Vols 01–06, and a de-duplicated bibliography. It introduces no new measurements. Every value here traces to the volume that first established it, cited in each row or paragraph as “(Vol N)”; anything flagged (est.) in its origin volume keeps that flag here rather than being hardened into a specification. Where a figure appears in more than one volume, the number given is the one the series has carried consistently — the anchor identity 1 in H₂O = 249.089 Pa and the busker-organ working pressure 5 in H₂O = 127 mm ≈ 1.245 kPa ≈ 12.45 mbar above all (Vol 01 §4; Vol 04 §1.2).
Note: This is a reference, not a procedure. Do not use a glossary line or a table row as the sole authority for building or setting a wind system — follow the full treatment in the volume cited (leathering and leak-finding in Vol 06; reservoir loading in Vol 03; sizing in Vol 04).
7.1 The wind chain, recapped in one page
The whole series develops a single invariant chain: air is raised under pressure, stored and regulated to a set value, conveyed to the chest, and tapped by the pipes on demand. Pressure is held constant from the reservoir onward; flow is zero until a pallet opens and then equals the running sum of what the sounding pipes draw (Vol 01 §2–3). The diagram below recaps that chain with the key annotation from each of Vols 01–06 attached to the stage it governs.
7.2 Pressure-unit conversion table
The trade quotes wind pressure as a water-gauge column; the series fixes its conversions once, on the anchor identity below, and every volume reuses them (Vol 01 §4; Vol 04 §1.2). The pascal (Pa = N/m²) is the SI unit; the millibar (mbar = 100 Pa = hPa) is convenient because organ pressures land in single- and double-digit mbar.
Anchor identity: 1 in H₂O = 25.4 mm H₂O = 249.089 Pa = 2.491 mbar ≈ 0.0361 psi (at ~20 °C).
Table 1 — 2. Pressure-unit conversion table
| in H₂O | mm H₂O | Pa | mbar (hPa) | psi | Where it lands |
|---|---|---|---|---|---|
| 1 | 25.4 | 249 | 2.49 | 0.0361 | unit anchor |
| 2 | 50.8 | 498 | 4.98 | 0.0723 | soft chamber organ (low end) |
| 2.5 | 63.5 | 623 | 6.23 | 0.0903 | Baroque flue chorus (low end) |
| 3 | 76.2 | 747 | 7.47 | 0.108 | small barrel / busker (low end) |
| 3.5 | 88.9 | 872 | 8.72 | 0.126 | chamber organ (high end) |
| 4 | 101.6 | 996 | 9.96 | 0.144 | Baroque chorus (high end) |
| 5 | 127 | 1245 | 12.45 | 0.181 | John Smith Universal busker |
| 8 | 203.2 | 1993 | 19.93 | 0.289 | band / fairground organ (low end) |
| 10 | 254 | 2491 | 24.91 | 0.361 | romantic flue / band organ |
| 15 | 381 | 3736 | 37.36 | 0.542 | band organ (high) / reeds (low) |
| 30 | 762 | 7473 | 74.73 | 1.084 | high-pressure solo reed (Tuba) |
| 50 | 1270 | 12454 | 124.5 | 1.805 | State Trumpet (top of range) |
(Computed at 1 in H₂O = 249.089 Pa, ~20 °C, matching Vol 01 §4 and Vol 04 §1.2. Flow reference: 1 CFM = 0.4719 L/s, so 1 L/s ≈ 2.119 CFM.)
7.2.1 Typical working pressures by organ type
Condensed from Vol 01 §5 (Organ Historical Society; standard organ-building texts; band-organ literature). Individual instruments vary, and a single large organ commonly winds different divisions at different pressures.
Table 2 — 2.1 Typical working pressures by organ type
| Organ type | Typical pressure | Metric |
|---|---|---|
| Chamber / house / continuo | ~2–3½ in H₂O | ≈ 50–89 mm; 5–9 mbar |
| Baroque church flue chorus | ~2½–4 in H₂O | ≈ 64–102 mm; 6–10 mbar |
| Busker / small barrel organ | ~3–5 in H₂O | ≈ 76–127 mm; 7.5–12.5 mbar (John Smith ≈ 5) |
| Romantic / orchestral flues, chorus reeds | ~5–15 in H₂O | ≈ 127–381 mm; 12–37 mbar |
| Fairground / band organ | ~8–15 in H₂O | ≈ 203–381 mm; 20–37 mbar |
| High-pressure solo reeds (Tuba, State Trumpet) | ~15–50 in H₂O | ≈ 381–1270 mm; 37–125 mbar |
7.2.2 A pressure-unit nomograph
The nomograph reads the same pressure across five parallel scales: lay a straight-edge vertically through a value on any scale and read the equivalent on the others. It is the conversion table in graphical form, with the four working bands (busker, church, band organ, high-pressure reed) marked.
7.3 Glossary of wind-system terms
Roughly thirty terms used across the series, each with the volume that develops it. Definitions are one-line reminders, not substitutes for the treatment cited.
Table 3 — 3. Glossary of wind-system terms
| Term | Definition | Vol |
|---|---|---|
| Blower (electric centrifugal) | Rotary fan that raises wind at working pressure; the near-universal raiser since ~1900 | Vol 02 §3.6 |
| Calcant | The blower-boy: a person who foot-pumped the feeders before electric blowers | Vol 02 §3.2 |
| Chest / windchest / pallet box | The pressurized box beneath the pipes; a pallet under each note admits wind to that pipe | Vol 01 §2 |
| Compensating ribs | See inverted ribs — a rib course folded to cancel the reservoir’s pressure drift | Vol 03 §3 |
| Concussion bellows / winker | A small spring-loaded bellows tapped into the wind that damps transient pressure surges | Vol 05 §4.3 |
| Cuneiform (wedge) bellows | A wedge-shaped bellows hinged at one end; the classic feeder and early reservoir form | Vol 02 §1.1 |
| Double-rise reservoir | Reservoir with two rib courses (one inverted); steadier pressure than single-rise | Vol 03 §4 |
| Dynamic (velocity) pressure | The ½ρv² component read when air is moving; why tappings are taken flush to the wall | Vol 04 §2 |
| Feeder | A one-way pumping bellows that raises wind into the reservoir; flap-valve leathers make it one-way | Vol 02 §1 |
| Flow | Volume of air per unit time (L/s or CFM); set by the pipes drawing, not by the reservoir | Vol 01 §3.2; Vol 04 §3 |
| Foot (of pipe) | The pipe’s inlet, with the foot-hole and flue/windway where the wind becomes a jet | Vol 04 §3.1 |
| Gusset | A leather corner-piece letting the bellows folds flex airtight | Vol 06 §3 |
| in H₂O (inches water gauge) | The trade unit of wind pressure: the height of water column the wind supports; 1 in = 249.089 Pa | Vol 01 §4; Vol 04 §1 |
| Inverted (compensating) ribs | One rib course folding inward while another folds outward, keeping pressure flat across the stroke | Vol 03 §3 |
| Manometer (U-tube / water gauge) | A part-filled U-tube reading pressure directly as the difference between its two water surfaces | Vol 04 §1 |
| ”Out of wind” | Flow demand exceeding supply, so the reservoir empties, pressure sags, and pipes go flat and quiet together | Vol 01 §3.2; Vol 04 §3.3 |
| Pallet | The valve under each note in the chest, opened by the key or paper roll to admit wind to the pipe | Vol 01 §2 |
| Prime mover / raiser | Whatever drives the feeders or blower: hand, foot, crank, weight, water engine, or electric motor | Vol 02 §3 |
| Pressure (static) | Force per unit area of the wind at rest relative to the trunk wall; the quantity set for voicing | Vol 01 §3.1; Vol 04 §2 |
| Regulator | The function of holding pressure constant as the reservoir fills and empties (often the reservoir itself) | Vol 03 §1 |
| Relief / spill valve | A sprung valve that dumps excess wind when the feeders overfill, capping the pressure | Vol 03 §6; Vol 06 §5.4 |
| Reservoir | The store that buffers the raiser’s pulsation and holds a set pressure; the heart of regulation | Vol 03 |
| Rib | A hinged frame member forming one fold of a bellows or reservoir | Vol 03 §3 |
| Robbing | One pipe stealing wind from another when both speak, so a note wavers as others enter | Vol 05 §2 |
| Schwimmer | A floating-lid regulator built into the chest; the common small-organ modern form | Vol 03 §5 |
| Single-rise reservoir | Reservoir with one rib course; simpler but less steady than double-rise | Vol 03 §4 |
| Tremulant | A device that deliberately pulsates the wind for a vibrato; beating or fan types, a few Hz | Vol 05 §5 |
| Undulating rank (Voix Céleste) | A rank tuned slightly sharp that beats against a unison rank; the busker organ’s tremolo substitute | Vol 05 §5.3 |
| Water (hydraulic) engine | A raiser driven by mains or head water pressure, once common before electricity | Vol 02 §3.5 |
| Wind | Term of art: a continuous, regulated supply of low-pressure air, not a per-note puff | Vol 01 §1 |
| Wind trunk (conveyance) | The duct carrying regulated wind from reservoir to chest; must be generous or it throttles flow | Vol 01 §2; Vol 04 §4 |
7.4 Formula and quick-reference card
Every relation the series uses, in one block. Symbols: p = pressure (Pa), ρ = density (kg/m³), g = 9.81 m/s², h = head (m), v = velocity (m/s), Q = volume flow (m³/s), A = area (m²).
Table 4 — 4. Formula and quick-reference card
| Quantity | Formula | Worked at the busker 5 in H₂O | Source |
|---|---|---|---|
| Manometer / hydrostatic head | p = ρ g h (ρ_water ≈ 998 kg/m³) | 127 mm of water → 1245 Pa | Vol 04 §1.1 |
| Inch-of-water unit | 1 in H₂O = 249.089 Pa = 25.4 mm | 5 in → 1245 Pa = 12.45 mbar | Vol 01 §4 |
| Flue jet velocity | v = √(2 p / ρ_air) (ρ_air ≈ 1.2 kg/m³) | √(2×1245/1.2) ≈ 45.6 m/s | Vol 04 §3.1 |
| Volume flow of a flue | Q = A_flue × v | 3 mm² × 45.6 m/s ≈ 0.14 L/s | Vol 04 §3.1 |
| Trunk minimum area | A ≥ Q_peak / v_max (v_max ≈ 8–10 m/s est.) | 4 L/s ÷ 8 m/s ≈ 500 mm² | Vol 04 §4 |
| Flow unit conversion | 1 CFM = 0.4719 L/s; 1 L/s ≈ 2.119 CFM | — | Vol 01 §4; Vol 04 §1.2 |
7.4.1 Rules of thumb (all est., check on the manometer)
- Pressure and flow are independent (Vol 01 §3). The reservoir spring/weight sets pressure; the pipes set flow. Diagnose and fix them separately.
- Raiser capacity ≥ sustained average demand + 50–100 % headroom, so the reservoir refills between chords (Vol 04 §4). For a ~20-note rank the average lands at ~2–4 L/s (~4–8 CFM) (Vol 04 §3.2).
- Reservoir volume ≥ the peak surge it must bridge — a couple of seconds of average draw (a few litres swept) rides over ordinary chord attacks (Vol 04 §4).
- Trunk velocity kept well below ~8–10 m/s so velocity pressure is not spent as a chest-starving pressure drop (Vol 04 §2, §4).
- The manometer is the arbiter. Read static pressure at rest and under the worst-case chord; the gap between the two numbers is the wind system’s report card (Vol 04 §2, §3.3).
7.4.2 Symptom → cause → fix (condensed from Vol 06 §8)
Table 5 — 4.2 Symptom → cause → fix (condensed from Vol 06 §8)
| Symptom | Likely cause | Fix |
|---|---|---|
| Pressure steady but wrong (organ uniformly sharp/flat, too loud/soft) | Reservoir spring/weight set wrong | Re-set the spring; re-trim the spill valve (Vol 03 §2, §6) |
| Pressure sags only under a chord, correct at idle | Flow shortfall: undersized raiser/reservoir/trunk, or a leak | Bigger feeders/blower, larger reservoir, fatter trunk; hunt leaks (Vol 04 §4; Vol 06 §7) |
| Pressure wavers in step with the pump/crank | Regulation failing to buffer pulsation | Feeder phasing, stiffer/larger reservoir, add winker (Vol 05 §1, §4) |
| One note wavers when others enter | Robbing | More trunk/chest area, bigger reservoir, winker (Vol 05 §2, §4) |
| Slow, dull, or non-speaking pipes | Pressure too low, or leak upstream | Raise pressure to voicing value; find and seal leaks (Vol 06 §7) |
7.5 Cross-index to Vols 01–06
Section-level pointers into the series, for finding where a topic is developed in full. Wording matches the volumes so the website resolves the links cleanly.
Table 6 — 5. Cross-index to Vols 01–06
| Topic | Where |
|---|---|
| What “wind” is; pressure vs flow; the chain end to end; units; typical pressures | Vol 01 §1–5 (The Wind Chain) |
| The feeder as a one-way pump; wedge bellows; flap valves; displacement | Vol 02 §1 |
| Alternation: two feeders in anti-phase; three feeders at 120° (busker) | Vol 02 §2 |
| Prime movers: hand, calcant, crank, weight, water engine, electric blower | Vol 02 §3 |
| What the reservoir is for; loading the lid (springs vs weights) | Vol 03 §1–2 |
| Inverted / compensating ribs; why a single course drifts | Vol 03 §3 |
| Single-rise vs double-rise; the Schwimmer floating-lid regulator | Vol 03 §4–5 |
| Relief / spill valve and the cut-off | Vol 03 §6 |
| The water manometer; why the column is the pressure; reading it at 5 in H₂O | Vol 04 §1 |
| Static vs dynamic (velocity) pressure; flush tappings | Vol 04 §2 |
| Wind consumption per pipe; jet velocity; peak vs average; big chords sag | Vol 04 §3 |
| Sizing raiser, reservoir, and trunk to demand | Vol 04 §4 |
| Why a regulated system still isn’t perfectly steady; robbing | Vol 05 §1–2 |
| Liveliness prized vs unsteadiness a fault; cures (double-rise, winkers, trunk) | Vol 05 §3–4 |
| The deliberate tremulant (beating, fan); the busker’s slightly-sharp rank | Vol 05 §5 |
| Airtightness; leather and cloth; gusseting and gluing; springs | Vol 06 §1–4 |
| Sizing feeders and reservoir for a 20-note organ; the spill valve | Vol 06 §5 |
| Materials shortlist; bring-up, leak-finding, troubleshooting | Vol 06 §6–9 |
7.6 Where this dive sits in the Crank-Organs program
Wind Systems is Dive 3 of Track 1 (Foundations & Theory) in the fifteen-dive Crank-Organs program (Crank-Organs README). It is theory and reference, applied across every organ in the program; the sibling dives take the wind system it describes into concrete builds and adjacent subsystems:
- The John Smith Universal Organ (Dive 5) — the applied small wind system, and the concrete worked example this whole series cites: three 120°-phased feeders, a ~5 in H₂O sprung reservoir with a spill valve, and a manometer on the bench (John Smith Universal, Vol 04 — Wind System). Every busker number in Vols 01–06 traces to that build.
- How Organ Pipes Make Sound (Dive 2) — the load at the end of the chain, and the reason steady wind at pressure matters: how wind pressure sets jet velocity (v = √(2p/ρ_air)), why over-pressure over-blows a pipe and under-pressure starves it, and why pipes are voiced at one specific pressure (How Organ Pipes Make Sound, Vol 2/6).
- Encoding the Music (Dive 4, planned) — what opens the pallets the wind waits behind: barrels, book, paper rolls, and MIDI. The wind system holds the pressure; the encoding decides when each note taps it.
- Turning the Crank: Hand, Electric Motor & Automation (Dive 12, planned) and Steam Organs & Calliopes (Dive 13, planned) — the prime movers of Vol 02 §3 taken further: motorised and automated cranking, and the steam-raised wind of the fairground calliope.
- Materials, Construction & Restoration — Classic and Modern (Dive 15, planned) — the leathers, cloths, woods, and glues of Vol 06 §2–4 and §6 in full, plus restoring the wind system of an antique organ.
7.6.1 Cross-references
- Wind Systems, Vols 01–06 — the whole series this volume indexes; see §5 for the section-level map.
- John Smith Universal Organ, Vol 04 — Wind System — the concrete busker build (~5 in H₂O, three 120°-phased feeders, sprung reservoir + spill valve, manometer) that anchors every small-scale number here.
- How Organ Pipes Make Sound, Vol 2/6 — the pipe as the load; wind pressure → jet velocity → loudness and pitch stability.
- Crank-Organs README — the fifteen-dive program map and this dive’s place in Track 1.
Sources
Consolidated and de-duplicated from the sources sections of Vols 01–06.
- Audsley, G. A., The Art of Organ Building (1905, public domain) — bellows, feeders, reservoirs, wind trunks, and regulation; the water-gauge convention; the ideal of a wind “absolutely steady” under all conditions of draw (Vols 01–06).
- Pykett, Colin, pykett.org.uk — “The organ wind supply,” “The physics of organ blowing,” and related articles on regulation, wind steadiness, blowing power and consumption, tremulants, and the reservoir as buffer between intermittent supply and demand; the U-tube as the reference gauge (Vols 01–05).
- Organ Historical Society and standard organ-building texts — typical working pressures by organ type; the U-tube manometer as the shop-standard instrument (Vols 01, 04).
- Standard fluid-statics / pitot-tube references — hydrostatic head p = ρgh fixing the water-column unit; static vs dynamic (velocity) pressure and flush wind tappings; Bernoulli v = √(2p/ρ) for the flue jet (Vol 04).
- Band-organ / mechanical-organ literature — Carousel Organ Association of America (COAA), Carousel Organ journal; Melvyn Wright (melright.com/busker) on busker-organ construction, feeders, reservoirs and spill valves; Ed Gaida and the Busker Organ Forum — the small crank/busker case and its pressures and consumption (Vols 01–06).
- John Smith Universal Organ dive (sibling, published) — the concrete small-organ worked example (~5 in H₂O; three 120°-phased feeders; sprung reservoir and spill valve) reused throughout this series (Vols 01–06).
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