{
 "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-port-cap",
 "name": "Tri-clamp port cap: 2 in, four 1/8 NPT ports for a fill valve, a gauge, a relief valve and an electrical pass-through",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I put a fill valve, a pressure gauge, a relief valve and a wire pass-through on a tri-clamp vessel?",
 "tags": [
  "ports",
  "npt",
  "fill valve",
  "gauge",
  "relief valve",
  "pass-through",
  "pressure",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "tri clamp cap with npt ports",
  "pressure gauge port tri clamp",
  "fill valve tri clamp",
  "relief valve port",
  "1/8 npt tri clamp cap",
  "wire pass through tri clamp"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/tri-clamp-port-cap/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-port-cap/sheet.txt",
 "sheet": {
  "basis": "ISO 2852 face and 20° back exactly as the flat end cap; 1/8-27 NPT (ASME B1.20.1): major Ø10.29, hand-tight engagement L1 4.1, effective thread L2 6.7, tap drill Ø8.6 (as on this site's NPT thread envelope page)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The flat end cap's profile with a Ø46.7 neck to 18 mm. Four 1/8 NPT ports on Ø24, 90° apart, each drawn as its tap drill, Ø8.6 × 10 deep from the top (the thread as the tap-drill bore, the convention of the thread envelopes on this site), then a passage on into the vessel.",
   "Three ports for the fill valve, the pressure gauge and the pressure relief valve (Ø3 passages). The fourth takes a sealed electrical pass-through with a 1/8 NPT male thread, for the generator's three leads; its passage is Ø6 so the leads reach it from inside.",
   "On the sealed generator this cap sits on the motor-mount plate at the top of the cross, so all four see the crankcase, which follows the working space's mean pressure through the bleed.",
   "Design charge 2 bar gauge. That pressure pushes a cap off its joint with 354 N over the Ø47.5 bore, 501 N if it acts out to the gasket bead (Ø56.5); at a 3 bar relief setting 532–752 N. Every clamp, fitting, pass-through and cap on the vessel must be rated above the relief setting; I set the relief valve no higher than the lowest of those ratings."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "face",
     "ISO 2852, as the 2 in flat end cap"
    ],
    [
     "height",
     18
    ],
    [
     "ports",
     "4 × 1/8-27 NPT on Ø24, 90° apart"
    ],
    [
     "tap drill",
     "Ø8.6 × 10"
    ],
    [
     "thread (B1.20.1)",
     "Ø10.29 major, L1 4.1, L2 6.7"
    ],
    [
     "passages",
     "Ø6 (pass-through), 3 × Ø3"
    ],
    [
     "end force, 2 bar g",
     "354–501 N"
    ],
    [
     "end force, 3 bar g",
     "532–752 N"
    ]
   ]
  }
 },
 "sheet_text": "Tri-clamp port cap: 2 in, four 1/8 NPT ports for a fill valve, a gauge, a relief valve and an electrical pass-through — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-port-cap/  (CC BY 4.0)\nBasis: ISO 2852 face and 20° back exactly as the flat end cap; 1/8-27 NPT (ASME B1.20.1): major Ø10.29, hand-tight engagement L1 4.1, effective thread L2 6.7, tap drill Ø8.6 (as on this site's NPT thread envelope page)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The flat end cap's profile with a Ø46.7 neck to 18 mm. Four 1/8 NPT ports on Ø24, 90° apart, each drawn as its tap drill, Ø8.6 × 10 deep from the top (the thread as the tap-drill bore, the convention of the thread envelopes on this site), then a passage on into the vessel.\n- Three ports for the fill valve, the pressure gauge and the pressure relief valve (Ø3 passages). The fourth takes a sealed electrical pass-through with a 1/8 NPT male thread, for the generator's three leads; its passage is Ø6 so the leads reach it from inside.\n- On the sealed generator this cap sits on the motor-mount plate at the top of the cross, so all four see the crankcase, which follows the working space's mean pressure through the bleed.\n- Design charge 2 bar gauge. That pressure pushes a cap off its joint with 354 N over the Ø47.5 bore, 501 N if it acts out to the gasket bead (Ø56.5); at a 3 bar relief setting 532–752 N. Every clamp, fitting, pass-through and cap on the vessel must be rated above the relief setting; I set the relief valve no higher than the lowest of those ratings.\n\nfeature  value\nface  ISO 2852, as the 2 in flat end cap\nheight  18.0\nports  4 × 1/8-27 NPT on Ø24, 90° apart\ntap drill  Ø8.6 × 10\nthread (B1.20.1)  Ø10.29 major, L1 4.1, L2 6.7\npassages  Ø6 (pass-through), 3 × Ø3\nend force, 2 bar g  354–501 N\nend force, 3 bar g  532–752 N\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- ASME: ASME B1.20.1 Pipe Threads, General Purpose, Inch (NPT): 1/8-27 major Ø10.29, hand-tight engagement L1 4.1, effective thread L2 6.7; tap drill Ø8.6 as on this site's NPT thread envelopes — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch\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, 1 parts): https://xemstudio.com/files/hardware/tri-clamp-port-cap/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-port-cap\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": "ASME",
   "title": "ASME B1.20.1 Pipe Threads, General Purpose, Inch (NPT): 1/8-27 major Ø10.29, hand-tight engagement L1 4.1, effective thread L2 6.7; tap drill Ø8.6 as on this site's NPT thread envelopes",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/b1-20-1-pipe-threads-general-purpose-inch",
   "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": [
  "npt-thread-envelopes",
  "tri-clamp-end-cap",
  "tri-clamp-motor-mount-plate",
  "sanitary-clamp-crosses",
  "list-tri-clamp-sealed-diaphragm-generator"
 ],
 "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": "cap face",
   "exact": "ISO 2852 (as tc-cap-2in-flat)",
   "mates": "standard clamp + Type B gasket",
   "fit": "clamp",
   "files": "all"
  },
  {
   "feature": "ports",
   "exact": "4 × 1/8-27 NPT, tap drill Ø8.6 × 10 (ASME B1.20.1)",
   "mates": "fill valve, pressure gauge, relief valve, sealed electrical pass-through (1/8 NPT male)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "passages",
   "exact": "Ø6 (pass-through) and 3 × Ø3",
   "mates": "motor leads; gas to the ports",
   "fit": "designed",
   "files": "all"
  }
 ],
 "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": "What thread are the ports?",
   "a": "1/8-27 NPT (ASME B1.20.1), drawn as the Ø8.6 tap drill 10 deep; the effective thread length L2 is 6.7 mm."
  },
  {
   "q": "How do the generator's wires get out?",
   "a": "Through a sealed electrical pass-through screwed into the fourth 1/8 NPT port; the Ø6 passage below it leads the three motor leads up from the crankcase."
  },
  {
   "q": "How hard does 2 bar push on a 2 in cap?",
   "a": "354 N over the bore, 501 N out to the gasket bead."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "port-cap-2in-4x-npt18",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-port-cap/port-cap-2in-4x-npt18.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-port-cap/port-cap-2in-4x-npt18.stl",
   "note": "2 in port cap: tc_cap profile with a Ø46.7 neck to 18; 4 × 1/8 NPT ports on Ø24 at 90°: tap drill Ø8.6 × 10 from the top (thread as the tap-drill bore), then Ø6 (electrical pass-through, 0°) or Ø3 (fill, gauge, relief) to the recess floor"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-port-cap/index.md"
}