# Optical bubble counter for a blow-off line: 5 mm LED break-beam, ¼ in barbs

> How do I count fermentation bubbles electronically?

- Category: Hardware › Sanitary clamp fittings
- Kind: Hardware
- 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
- Page: https://xemstudio.com/objects/tri-clamp-bubble-counters/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-bubble-counters · Plain text: https://xemstudio.com/objects/tri-clamp-bubble-counters/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- 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.

## Sizes

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

## Where the files are

- GW Kent: [Tri-clamp fittings guide: tube OD, flange OD and ID per size to 12 in; solid cap thickness](https://www.gwkent.com/triclamp-guide) — web — publisher's guide; dimensions cited
- 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)](https://shop.andersonprocess.com/media/assets/product/documents/rubber-fab-tri-clamp-dimensions.pdf) — PDF — maker chart; dimensions are facts (verify at link)

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-bubble-counters/index.json

- optical-bubble-counter-1-4in-barbs: [STEP](https://xemstudio.com/files/hardware/tri-clamp-bubble-counters/optical-bubble-counter-1-4in-barbs.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-bubble-counters/optical-bubble-counter-1-4in-barbs.stl) — optical bubble counter: Ø24 × 70 chamber, ¼ in barbs in and out, inlet tube to 10 above the floor, two Ø5.1 LED holes facing across the bubble path 22 up

## Questions

**What sensor?**

A 5 mm IR LED on one side and a 5 mm IR phototransistor on the other, pressed into the Ø5.1 holes.

## Fits with

- [Tri-clamp brewing sensor lids: 4, 6 and 8 in caps with every port a fermenter needs](https://xemstudio.com/objects/tri-clamp-brewing-sensor-lids/)
- [Tri-clamp × hose barb adapters (14MPHR style): ½ to 4 in clamp, ¼ to 4 in hose](https://xemstudio.com/objects/tri-clamp-hose-barb-adapters/)
- [Espressif ESP32-DevKitC](https://xemstudio.com/objects/esp32-devkitc/)