Tri-clamp rolling-diaphragm power head, 2 in: standard clamp face, cylinder, rod guide and crank tower, with its diaphragm seat ring — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-rd-power-head/  (CC BY 4.0)
Basis: ISO 2852 face, rim, recess and 20° back cone as the flat end cap on this site; rolling-diaphragm bore, radii and stroke from the published 1.50 in size; 625 and 5 × 8 × 12 bushing sizes from their standards; crank geometry is a design value
Catalog version: 2026-10-20

Sizes: see table below
- One part behind a standard 2 in clamp joint. Its clamped end is a standard ISO 2852 2 in face: the land, the 2.85 mm rim, the 1.6 mm recess inside Ø56.5 and the 20° back cone, exactly as an end cap's, so the standard clamp closes on it and it goes on any 2 in ferrule.
- The diaphragm's flange (0.51) takes the place of the gasket. Between the flange and the head sits the seat ring: 1.19 mm on the land and down into the head's recess inside Ø56.5, so flange plus ring are the 1.7 mm of a Type B gasket's web and the clamp closes exactly as it does on a gasket. The ring carries the 1/16 in mouth radius the diaphragm wall rolls off, and its Ø38.10 bore runs on into the head's.
- Behind the ring: the Ø38.10 bore the diaphragm rolls in, down to a floor 49 mm from the clamp plane with four Ø6 vents so the back of the diaphragm is at air pressure; a Ø16 boss with an Ø8 seat for two 5 × 8 × 12 sleeve bushings that guide the Ø5 tube piston rod.
- A tower on −Y carries two 625 bearings (Ø16 × 5 pockets, 24 apart) on a Ø5 crankshaft 188 mm from the clamp plane: a 20 mm stroke crank disc on the shaft end, a conrod-80 down to the rod yoke. The flywheel goes on the far end.
- The same head goes on the 2 in cup of the beta (straight up) and on the branch of a standard 2 in tee in the Ringbom and gamma (sideways).

feature  value_mm
clamp face  ISO 2852 2 in, face plane 0.85 from the clamp plane
seat ring on the land  1.19
seat ring in the recess  2.79
bore Ø  38.1
bore depth  49.0
bushing seat  Ø8 × 24
bearing pockets  Ø16 × 5, y −26 and −50
shaft axis  188.0
stroke  20.0

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- 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
- 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
- Marsh Bellofram: Rolling diaphragm design manual (2022): nomenclature, height formula, standard-size tables, hardware radii — PDF — publisher's manual; dimensions cited, nothing copied — https://damapi.marshbellofram.com/uploads/Bellofram_Diaphragm_Design_Manual_2022_7a922642c3.pdf
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/tri-clamp-rd-power-head/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-rd-power-head