{
 "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": "tri-clamp-diaphragm-head",
 "name": "Tri-clamp diaphragm head: 1.5 and 2 in, membrane in place of the gasket",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I make a diaphragm power piston on a tri-clamp fitting?",
 "tags": [
  "diaphragm",
  "head",
  "power piston",
  "membrane",
  "ferrule",
  "cap",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "tri clamp diaphragm",
  "diaphragm stirling engine tri clamp",
  "tri clamp membrane head",
  "flexible diaphragm power piston",
  "diaphragm head 2 inch tri clamp",
  "diaphragm stirling power piston"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 2,
 "url": "https://xemstudio.com/objects/tri-clamp-diaphragm-head/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-diaphragm-head/sheet.txt",
 "sheet": {
  "basis": "ISO 2852 clamp face and 20° back cone from the ferrule on this site (rim 2.85, recess 1.6, back cone continued down to the tube OD at the ferrule's own hub height), ASME BPE tube bores; membrane cavity sized from the diaphragm stroke",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The head is a cap-style part that clamps onto any standard ferrule with the standard clamp. The membrane goes where the gasket would: its bead sits in the 1.6 mm recesses of the ferrule and the head, its web between the two lands, so the clamp closes exactly as on a Type B gasket.",
   "The back of the clamp face is the ferrule's 20° cone, continued down to the tube OD (Ø38.1 / Ø50.8) at 5.25 / 5.25 mm from the face, so the clamp groove meets the head just as it meets a ferrule (0.4 mm take-up, 0.6 mm squeeze). Behind that the head is a neck at the tube OD.",
   "Behind the membrane: a cavity at the bore (Ø34.8 / Ø47.5) deep enough for the centre disc and its nuts at full outward travel (1.5 in ±5, 2 in ±7.5 mm), a pocket for the rod boss, a Ø3 rod guide straight through a Ø16 boss, and four Ø4 vents so the space behind the membrane stays at air pressure.",
   "Fit: the Ø3 guide is a running fit on the Ø3 rod; the face is a clamp face. Everything else is drawn at size."
  ],
  "table": {
   "columns": [
    "size_in",
    "flange_mm",
    "groove_mm",
    "neck_od_mm",
    "cavity_dia_mm",
    "cavity_depth_mm",
    "back_mm",
    "guide_top_mm",
    "design_stroke_mm"
   ],
   "rows": [
    [
     "2",
     64,
     56.5,
     50.8,
     47.5,
     13.15,
     17,
     30,
     15
    ],
    [
     "1.5",
     50.5,
     43.5,
     38.1,
     34.8,
     10.65,
     14.5,
     27.5,
     10
    ]
   ]
  }
 },
 "sheet_text": "Tri-clamp diaphragm head: 1.5 and 2 in, membrane in place of the gasket — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-diaphragm-head/  (CC BY 4.0)\nBasis: ISO 2852 clamp face and 20° back cone from the ferrule on this site (rim 2.85, recess 1.6, back cone continued down to the tube OD at the ferrule's own hub height), ASME BPE tube bores; membrane cavity sized from the diaphragm stroke\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The head is a cap-style part that clamps onto any standard ferrule with the standard clamp. The membrane goes where the gasket would: its bead sits in the 1.6 mm recesses of the ferrule and the head, its web between the two lands, so the clamp closes exactly as on a Type B gasket.\n- The back of the clamp face is the ferrule's 20° cone, continued down to the tube OD (Ø38.1 / Ø50.8) at 5.25 / 5.25 mm from the face, so the clamp groove meets the head just as it meets a ferrule (0.4 mm take-up, 0.6 mm squeeze). Behind that the head is a neck at the tube OD.\n- Behind the membrane: a cavity at the bore (Ø34.8 / Ø47.5) deep enough for the centre disc and its nuts at full outward travel (1.5 in ±5, 2 in ±7.5 mm), a pocket for the rod boss, a Ø3 rod guide straight through a Ø16 boss, and four Ø4 vents so the space behind the membrane stays at air pressure.\n- Fit: the Ø3 guide is a running fit on the Ø3 rod; the face is a clamp face. Everything else is drawn at size.\n\nsize_in  flange_mm  groove_mm  neck_od_mm  cavity_dia_mm  cavity_depth_mm  back_mm  guide_top_mm  design_stroke_mm\n2  64.0  56.5  50.8  47.5  13.15  17.0  30.0  15.0\n1.5  50.5  43.5  38.1  34.8  10.65  14.5  27.5  10.0\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- ISO (via iTeh sample): ISO 2852 clamp liners: face profile and flange / groove diameters — PDF — standard excerpt; dimensions are facts — https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf\n- ASME: BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall) — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/tri-clamp-diaphragm-head/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-diaphragm-head\n",
 "sources": [
  {
   "publisher": "ISO (via iTeh sample)",
   "title": "ISO 2852 clamp liners: face profile and flange / groove diameters",
   "url": "https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf",
   "formats": [
    "PDF"
   ],
   "license": "standard excerpt; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall)",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment",
   "formats": [
    "standard"
   ],
   "license": "ASME; dimensions are facts",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine 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": [
  "tri-clamp-diaphragm-membrane",
  "tri-clamp-diaphragm-disc",
  "tri-clamp-ferrule",
  "tri-clamp-clamps",
  "sanitary-clamp-tees",
  "list-tri-clamp-tee-diaphragm-gamma",
  "list-tri-clamp-elbow-diaphragm-alpha"
 ],
 "fits": [],
 "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": [
  {
   "feature": "clamp face",
   "exact": "ISO 2852 (land Ø43.5–Ø50.5 / Ø56.5–Ø64, rim 2.85, 20° back to the tube OD)",
   "mates": "standard clamp + membrane bead",
   "fit": "clamp",
   "files": "diaphragm-head-"
  },
  {
   "feature": "bead recess",
   "exact": "Ø43.5 / Ø56.5 × 1.6",
   "mates": "membrane bead",
   "fit": "clamp",
   "files": "diaphragm-head-"
  },
  {
   "feature": "rod guide",
   "exact": "Ø3",
   "mates": "Ø3 diaphragm rod (slides through it)",
   "fit": "run",
   "files": "diaphragm-head-"
  },
  {
   "feature": "membrane cavity",
   "exact": "Ø34.8 × 10.65 / Ø47.5 × 13.15 from the face",
   "mates": "centre disc and nuts at full travel",
   "fit": "designed",
   "files": "diaphragm-head-"
  },
  {
   "feature": "boss pocket",
   "exact": "Ø12 × 16.65 / Ø12 × 19.15 from the face",
   "mates": "rod boss at full travel",
   "fit": "designed",
   "files": "diaphragm-head-"
  },
  {
   "feature": "vents",
   "exact": "4 × Ø4",
   "mates": "air behind the membrane",
   "fit": "designed",
   "files": "diaphragm-head-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "Does the diaphragm head fit a standard tri-clamp ferrule?",
   "a": "Yes: the face and the 20° back are the ISO 2852 profile, so the standard clamp closes on it and the membrane bead sits where the gasket bead would."
  },
  {
   "q": "How far can the rod move?",
   "a": "2 in: ±7.5 mm (15 mm stroke); 1.5 in: ±5 mm (10 mm stroke). The cavity is drawn for that travel with 1.4 mm to spare behind the nuts."
  },
  {
   "q": "Why the vents?",
   "a": "So the air behind the membrane does not act as a spring against the engine; the working gas is only on the ferrule side."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "diaphragm-head-2in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-diaphragm-head/diaphragm-head-2in.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-diaphragm-head/diaphragm-head-2in.stl",
   "note": "2 in diaphragm head: ISO 2852 face (land Ø56.5–Ø64, rim 2.85, recess 1.6 inside Ø56.5), 20° back cone to the tube OD Ø50.8 at 5.25, membrane cavity Ø47.5 × 13.15, boss pocket Ø12 × 19.15, Ø3 rod guide to 30.00, 4 × Ø4 vents"
  },
  {
   "file": "diaphragm-head-1.5in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-diaphragm-head/diaphragm-head-1.5in.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-diaphragm-head/diaphragm-head-1.5in.stl",
   "note": "1.5 in diaphragm head: ISO 2852 face (land Ø43.5–Ø50.5, rim 2.85, recess 1.6 inside Ø43.5), 20° back cone to the tube OD Ø38.1 at 5.11, membrane cavity Ø34.8 × 10.65, boss pocket Ø12 × 16.65, Ø3 rod guide to 27.50, 4 × Ø4 vents"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-diaphragm-head/index.md"
}