{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "pu-pneumatic-tube",
 "name": "PU pneumatic tube 4 to 12 mm OD (push-fit sizes)",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Pipe & fittings",
 "year": null,
 "question": "What is the ID of 6 mm PU pneumatic tube?",
 "tags": [
  "pu tube",
  "pneumatic",
  "polyurethane",
  "tube",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "pu tube 6x4",
  "pneumatic tube sizes",
  "6mm air line id",
  "polyurethane tubing dimensions",
  "push fit tube size"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 5,
 "url": "https://xemstudio.com/objects/pu-pneumatic-tube/",
 "sheet_txt": "https://xemstudio.com/objects/pu-pneumatic-tube/sheet.txt",
 "sheet": {
  "basis": "ISO 6432-style metric PU pneumatic tube sizes (4 / 6 / 8 / 10 / 12 mm OD); each file a 50 mm length",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "PU pneumatic tube, OD × ID: 4×2.5, 6×4, 8×5.5, 10×6.5, 12×8 mm; each file is a 50 mm length at exact OD and ID.",
   "It is stiff tube made for push-fit fittings, typically rated 10 bar.",
   "Push-fit fittings grip the tube OD, so the push-fit socket is drawn at the tube OD exactly.",
   "On my pressurised engines the line is 6 mm PU into push-fits."
  ],
  "table": {
   "columns": [
    "od_mm",
    "id_mm",
    "wall_mm"
   ],
   "rows": [
    [
     4,
     2.5,
     0.75
    ],
    [
     6,
     4,
     1
    ],
    [
     8,
     5.5,
     1.25
    ],
    [
     10,
     6.5,
     1.75
    ],
    [
     12,
     8,
     2
    ]
   ]
  }
 },
 "sheet_text": "PU pneumatic tube 4 to 12 mm OD (push-fit sizes) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/pu-pneumatic-tube/  (CC BY 4.0)\nBasis: ISO 6432-style metric PU pneumatic tube sizes (4 / 6 / 8 / 10 / 12 mm OD); each file a 50 mm length\nCatalog version: 2026-10-20\n\nSizes: see table below\n- PU pneumatic tube, OD × ID: 4×2.5, 6×4, 8×5.5, 10×6.5, 12×8 mm; each file is a 50 mm length at exact OD and ID.\n- It is stiff tube made for push-fit fittings, typically rated 10 bar.\n- Push-fit fittings grip the tube OD, so the push-fit socket is drawn at the tube OD exactly.\n- On my pressurised engines the line is 6 mm PU into push-fits.\n\nod_mm  id_mm  wall_mm\n4  2.5  0.75\n6  4  1.0\n8  5.5  1.25\n10  6.5  1.75\n12  8  2.0\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Hose barb — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Hose_barb\n- Wikipedia: Push-fit fitting — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Push-to-connect_fitting\n- McMaster-Carr: Tubing (free STEP per part, for your own design use; no redistribution) — STEP, PDF — McMaster-Carr site terms [verify license at link] — https://www.mcmaster.com/products/tubing/\n- Long Earth Society: Engine and rig builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 5 parts): https://xemstudio.com/files/hardware/pu-pneumatic-tube/index.json\nAPI: https://xemstudio.com/api/geometry?object=pu-pneumatic-tube\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Hose barb",
   "url": "https://en.wikipedia.org/wiki/Hose_barb",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Push-fit fitting",
   "url": "https://en.wikipedia.org/wiki/Push-to-connect_fitting",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "McMaster-Carr",
   "title": "Tubing (free STEP per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/products/tubing/",
   "formats": [
    "STEP",
    "PDF"
   ],
   "license": "McMaster-Carr site terms",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine and rig builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "push-fit-fittings",
  "silicone-tube",
  "hose-barbs"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "push-fit-fittings",
     "why": "tube OD into the socket drawn at the OD"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "silicone-tube",
     "why": "soft tube for barbs"
    }
   ]
  }
 ],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [],
 "faq": [
  {
   "q": "What is the ID of 6 mm PU tube?",
   "a": "4 mm (6 × 4); 4 mm tube is 2.5 ID, 8 mm tube is 5.5 ID."
  },
  {
   "q": "What pressure is PU pneumatic tube rated for?",
   "a": "Typically 10 bar."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "pu-tube-4x2.5-50",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-4x2.5-50.step",
   "stl": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-4x2.5-50.stl",
   "note": "PU pneumatic tube 4 OD × 2.5 ID, 50 mm"
  },
  {
   "file": "pu-tube-6x4-50",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-6x4-50.step",
   "stl": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-6x4-50.stl",
   "note": "PU pneumatic tube 6 OD × 4 ID, 50 mm"
  },
  {
   "file": "pu-tube-8x5.5-50",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-8x5.5-50.step",
   "stl": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-8x5.5-50.stl",
   "note": "PU pneumatic tube 8 OD × 5.5 ID, 50 mm"
  },
  {
   "file": "pu-tube-10x6.5-50",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-10x6.5-50.step",
   "stl": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-10x6.5-50.stl",
   "note": "PU pneumatic tube 10 OD × 6.5 ID, 50 mm"
  },
  {
   "file": "pu-tube-12x8-50",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-12x8-50.step",
   "stl": "https://xemstudio.com/files/hardware/silicone-tube-and-fittings/pu-tube-12x8-50.stl",
   "note": "PU pneumatic tube 12 OD × 8 ID, 50 mm"
  }
 ],
 "markdown": "https://xemstudio.com/objects/pu-pneumatic-tube/index.md"
}