# Tri-clamp caps with PG13.5 probe ports (12 mm pH, dissolved O₂ and CO₂ probes): 1½ to 4 in

> How do I mount a 12 mm pH probe on a tri-clamp?

- Category: Hardware › Sanitary clamp fittings
- Kind: Hardware
- Basis: Xem Studio design on the standard solid cap: PG13.5 (DIN 40430: Ø20.4 major, 1.41 pitch, Ø18.6 core) in a Ø30 boss, drawn as the core bore over 12 mm of thread, Ø12.5 through for the 12 mm probe shaft
- Page: https://xemstudio.com/objects/tri-clamp-pg13-5-probe-ports/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-pg13-5-probe-ports · Plain text: https://xemstudio.com/objects/tri-clamp-pg13-5-probe-ports/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

- Most process probes (pH, ORP, dissolved oxygen, dissolved CO₂, conductivity) are 12 mm shafts with a PG13.5 thread on the head: they screw straight into this port and seal on their own O-ring.
- Probe length sets how deep the tip reaches below the clamp face; pick the probe so its tip sits in the liquid at your lowest fill.
- 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

| clamp | ports | pg_major_mm | core_mm | probe_mm |
|---|---|---|---|---|
| 1–1½ | 1 | 20.4 | 18.6 | 12.0 |
| 2 | 1 | 20.4 | 18.6 | 12.0 |
| 3 | 2 | 20.4 | 18.6 | 12.0 |
| 3 | 3 | 20.4 | 18.6 | 12.0 |
| 4 | 3 | 20.4 | 18.6 | 12.0 |

## Where the files are

- DIN: [DIN 40430 Pg (Panzergewinde) threads: PG13.5 Ø20.4 major, 1.41 pitch (18 tpi), Ø18.6 core; the thread of 12 mm process probes (pH, dissolved O2 / CO2)](https://www.din.de/en) — standard — DIN; dimensions are facts (verify at link)
- 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 (5 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/index.json

- pg13-5-cap-1.5in-x1: [STEP](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-1.5in-x1.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-1.5in-x1.stl) — 1–1½ in cap with 1 × PG13.5 probe port: boss Ø30 × 16, core bore Ø18.6 × 12 (thread), Ø12.5 through
- pg13-5-cap-2in-x1: [STEP](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-2in-x1.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-2in-x1.stl) — 2 in cap with 1 × PG13.5 probe port: boss Ø30 × 16, core bore Ø18.6 × 12 (thread), Ø12.5 through
- pg13-5-cap-3in-x2: [STEP](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-3in-x2.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-3in-x2.stl) — 3 in cap with 2 × PG13.5 probe port: boss Ø30 × 16, core bore Ø18.6 × 12 (thread), Ø12.5 through
- pg13-5-cap-3in-x3: [STEP](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-3in-x3.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-3in-x3.stl) — 3 in cap with 3 × PG13.5 probe port: boss Ø30 × 16, core bore Ø18.6 × 12 (thread), Ø12.5 through
- pg13-5-cap-4in-x3: [STEP](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-4in-x3.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-pg13-5-probe-ports/pg13-5-cap-4in-x3.stl) — 4 in cap with 3 × PG13.5 probe port: boss Ø30 × 16, core bore Ø18.6 × 12 (thread), Ø12.5 through

## Questions

**Which probes fit?**

Any 12 mm probe with a PG13.5 head: most industrial pH, ORP, DO and dissolved-CO₂ probes.

## 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 probe gland caps: Ø4, Ø6 and ¼ in probes, 1 to 3 per cap](https://xemstudio.com/objects/tri-clamp-probe-gland-caps/)
- [Tri-clamp thermowells: 1½ and 2 in clamp, 2½ to 12 in insertion, ½ NPT top](https://xemstudio.com/objects/tri-clamp-thermowells/)