{
  "version": 2,
  "engineVersion": "pressure-2026-09-08",
  "conditions": { "altitude_ft": 0, "temperature_f": 0 },
  "safetyFactorPercent": 15,
  "reportMetadata": {
    "projectName": "Verification: cold round duct",
    "systemName": "Equation benchmark, not a design",
    "revision": "1",
    "preparedBy": "DuctStatic benchmark suite",
    "checkedBy": "",
    "notes": "Reproduces cold-zero-f: 2000 actual CFM, 100 ft of 16-inch round galvanized duct; imposed roughness 0.09144 mm; no fittings or terminal drop. Compare raw section friction, not fan static pressure or the safety-factor result. Not certification."
  },
  "layoutDir": 0,
  "customFittings": [],
  "tree": {
    "id": "c1",
    "type": "fan",
    "props": {
      "name": "Benchmark fan",
      "cfm": 2000,
      "fanType": "supply",
      "staticPressure_inWG": 0,
      "outletDuctType": "round",
      "outletDiameter_in": 16,
      "outletWidth_in": 16,
      "outletHeight_in": 16,
      "inletDuctType": "round",
      "inletDiameter_in": 16,
      "inletWidth_in": 16,
      "inletHeight_in": 16,
      "soundSource": "none",
      "lwOctave": [0,0,0,0,0,0,0,0],
      "lwOverall": null,
      "fanSpectrumPreset": "default"
    },
    "children": [
      {
        "id": "c2",
        "type": "duct",
        "props": {
          "name": "Cold round reference duct",
          "length_ft": 100,
          "material": "galv_spiral",
          "ductType": "round",
          "diameter_in": 16,
          "width_in": 16,
          "height_in": 16,
          "flipDirection": false,
          "pressureClass": "low",
          "roughness_override": null,
          "fittings": [],
          "internallyLined": false
        },
        "children": []
      },
      null
    ]
  }
}