Optical bubble counter for a blow-off line: 5 mm LED break-beam, ¼ in barbs — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-bubble-counters/  (CC BY 4.0)
Basis: Xem Studio design: a small water-filled chamber on the blow-off line; each bubble rising from the inlet tube crosses a beam between a 5 mm IR LED and a 5 mm phototransistor in two Ø5.1 holes
Catalog version: 2026-10-20

Sizes: see table below
- Run the blow-off hose from the lid barb (through a ½ × ¼ in reducing hose or a ¼ in barb port) into the inlet barb; fill the chamber about 35 mm deep with water or sanitiser so the beam (22 mm up) is under water. Each bubble breaks the beam once: count pulses on an ESP32 input to log the CO₂ rate.
- Print it in a clear material, or seal the LED holes with clear epoxy; mount it upright with two M3 screws through the base.
- Every clamp face is the ISO 2852 profile used across this site: 2.85 mm rim, flat face with the gasket groove (K 1.6 deep, R3 1.2 bottom, 23° walls, P2 0.8 edges) on C2, 20° back cone. Flange C3 / groove C2 / tube OD × wall, mm: ½–¾ in 25.0 / 20.4 (derived) / 12.7–19.05 × 1.65; 1–1½ in 50.5 / 43.5 / 25.4–38.1 × 1.65; 2 in 64.0 / 56.5 / 50.8 × 1.65; 2½ in 77.5 / 70.5 / 63.5 × 1.65; 3 in 91.0 / 83.5 / 76.2 × 1.65; 4 in 119.0 / 110.0 / 101.6 × 2.11; 6 in 166.9 (6.570 in) / 156.5 / 152.4 × 2.77; 8 in 217.7 (8.570 in) / 207.0 / 203.2 × 2.77; 10 in 268.5 / 261.0 / 254.0 × 3.40; 12 in 319.3 / 311.8 / 304.8 × 3.40.

chamber_bore_mm  chamber_h_mm  beam_height_mm  led_hole_mm  barbs
24  70  22  5.1  ¼ in in / out

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- GW Kent: Tri-clamp fittings guide: tube OD, flange OD and ID per size to 12 in; solid cap thickness — web — publisher's guide; dimensions cited — https://www.gwkent.com/triclamp-guide
- Rubber Fab: Tri-Clamp gasket dimensional chart: gasket ID, OD and bead diameter per size (2 in bead 2.22 in / 56.50 mm, 1.5 in 1.71 / 43.50, 3 in 3.29 / 83.50) — PDF — maker chart; dimensions are facts [verify license at link] — https://shop.andersonprocess.com/media/assets/product/documents/rubber-fab-tri-clamp-dimensions.pdf

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tri-clamp-bubble-counters/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-bubble-counters