Xem Studiomeasured geometry

Library › Hardware › Pipe & fittings ·

Silicone and PU tube, hose barbs and push-fit fittings (the transfer port)

What size silicone tube and barb for a Stirling engine transfer port? · Hardware · basis: Common silicone tube sizes (ID × OD, 1–2 mm wall), ISO 6432-style PU pneumatic tube (4/6/8/10/12 mm OD), barb geometry (OD = tube ID + 1.2, 3 barbs), push-fit envelopes

Long Earth Society build part. Transfer ports between hot and cold spools on the LES demonstrators. The engines · all LES parts

sizes
13 in table

Notes

  • Silicone tube ID × OD: 1×3, 2×4, 3×5, 4×6, 5×8, 6×9, 8×12, 10×14 mm; 60 Shore A, −60 to 200 °C, stretches over a barb 1.5 mm larger than its ID. PU pneumatic tube (push-fit): 4×2.5, 6×4, 8×5.5, 10×6.5, 12×8 OD×ID; stiff, rated 10 bar, 80 °C max.
  • Transfer port on a can/test-tube Stirling: 4 mm ID silicone, as short as possible (every mL of tube is dead volume that costs compression ratio); the can-cap port is Ø4.2 for a 4 mm barb. Larger engines: 6–8 mm ID.
  • Barbs: OD = tube ID + 1.2 mm, three 2.5 mm barbs, a hex base; printed barbs seal silicone tube fine (sand the layer lines). Push-fit fittings take the PU tube OD exactly: 6 mm tube into a 6 mm fitting; thread stubs G1/8 (9.73 OD) or G1/4 (13.16).
  • LES: 4 × 6 silicone between the hot and cold spools on the demonstrators; 6 mm PU + push-fits on the pressurised engines.

Sizes

tubeid_mmod_mmwall_mmbarb_od_mm
silicone131.02.2
silicone241.03.2
silicone351.04.2
silicone461.05.2
silicone581.56.2
silicone691.57.2
silicone8122.09.2
silicone10142.011.2
PU push-fit2.540.75push-fit
PU push-fit461.0push-fit
PU push-fit5.581.25push-fit
PU push-fit6.5101.75push-fit
PU push-fit8122.0push-fit

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

WikipediaHose barbwebCC BY-SA 4.0 (text)
WikipediaPush-fit fittingwebCC BY-SA 4.0 (text)
McMaster-CarrTubing (free STEP per part, for your own design use; no redistribution)STEP, PDFMcMaster-Carr site terms verify
Long Earth SocietyEngine and rig buildsweb, videoLES site

Free files

★ Free files 22 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

silicone-tube-1x3-50silicone tube 1 ID × 3 OD, 50 mmSTEP · STL
silicone-tube-2x4-50silicone tube 2 ID × 4 OD, 50 mmSTEP · STL
silicone-tube-3x5-50silicone tube 3 ID × 5 OD, 50 mmSTEP · STL
silicone-tube-4x6-50silicone tube 4 ID × 6 OD, 50 mmSTEP · STL
silicone-tube-5x8-50silicone tube 5 ID × 8 OD, 50 mmSTEP · STL
silicone-tube-6x9-50silicone tube 6 ID × 9 OD, 50 mmSTEP · STL
silicone-tube-8x12-50silicone tube 8 ID × 12 OD, 50 mmSTEP · STL
silicone-tube-10x14-50silicone tube 10 ID × 14 OD, 50 mmSTEP · STL
pu-tube-4x2.5-50PU pneumatic tube 4 OD × 2.5 ID, 50 mmSTEP · STL
pu-tube-6x4-50PU pneumatic tube 6 OD × 4 ID, 50 mmSTEP · STL
pu-tube-8x5.5-50PU pneumatic tube 8 OD × 5.5 ID, 50 mmSTEP · STL
pu-tube-10x6.5-50PU pneumatic tube 10 OD × 6.5 ID, 50 mmSTEP · STL
pu-tube-12x8-50PU pneumatic tube 12 OD × 8 ID, 50 mmSTEP · STL
barb-2mmhose barb for 2 mm ID tube, 3 barbs, hex base; print and tap or glueSTEP · STL
barb-3mmhose barb for 3 mm ID tube, 3 barbs, hex base; print and tap or glueSTEP · STL
barb-4mmhose barb for 4 mm ID tube, 3 barbs, hex base; print and tap or glueSTEP · STL
barb-6mmhose barb for 6 mm ID tube, 3 barbs, hex base; print and tap or glueSTEP · STL
barb-8mmhose barb for 8 mm ID tube, 3 barbs, hex base; print and tap or glueSTEP · STL
pushfit-4mm-g1-8push-fit fitting envelope: 4 mm tube, G1/8 thread stubSTEP · STL
pushfit-6mm-g1-8push-fit fitting envelope: 6 mm tube, G1/8 thread stubSTEP · STL
pushfit-6mm-g1-4push-fit fitting envelope: 6 mm tube, G1/4 thread stubSTEP · STL
pushfit-8mm-g1-4push-fit fitting envelope: 8 mm tube, G1/4 thread stubSTEP · STL

Plain text: sheet.txt · JSON: /api/geometry?object=silicone-tube-and-fittings

Silicone and PU tube, hose barbs and push-fit fittings (the transfer port), isometric render of a generated part
Render of barb-4mm from the free STEP; not to scale.

Fits with

Pipe thread envelopes: NPT (ANSI B1.20.1) and BSP (ISO 228 / 7), 1/8 to 1 inch, isometric render of a generated part
Pipe thread envelopes: NPT (ANSI B1.20.1) and BSP (ISO 228 / 7), 1/8 to 1 inch6 sizes★ 12 files
Can-engine printed kit: can caps, diaphragm clamps, displacer guides, crank stands, CD/platter hubs, syringe cradles, isometric render of a generated part
Can-engine printed kit: can caps, diaphragm clamps, displacer guides, crank stands, CD/platter hubs, syringe cradles7 sizes★ 23 files
Plastic syringes 1–60 mL as pistons and cylinders, isometric render of a generated part
Plastic syringes 1–60 mL as pistons and cylinders7 sizes★ 7 files
CS
O-rings, common metric sizes (ISO 3601)7 sizes★ free
Copper pipe (ASTM B88 Type L and M), 1/4 to 2 inch, isometric render of a generated part
Copper pipe (ASTM B88 Type L and M), 1/4 to 2 inch8 sizes★ 8 files

Questions

What silicone tube for a Stirling transfer port?

4 mm ID × 6 mm OD, kept under 30 mm long; the can-cap port is Ø4.2 for a 4 mm barb.

What barb size for 6 mm ID silicone tube?

7.2 mm barb OD (ID + 1.2), three barbs 2.5 mm long; silicone stretches on and seals without a clamp at low pressure.

What is the ID of 6 mm PU pneumatic tube?

4 mm (6 × 4); 8 mm tube is 5.5 ID, 4 mm tube is 2.5 ID.