# ISO-K and ISO-F large vacuum flanges (ISO 1609): OD, bolt circle, hole count and diameter, centering ring lip, DN63 to DN630, + ISO-F bolt-pattern templates

> What are the bolt circle, hole count and OD of an ISO-F (LF) vacuum flange DN100, DN160, DN250?

- Category: Hardware › Vacuum flanges
- Kind: Standard part
- Basis: Kurt J. Lesker's ISO tables as reproduced in Cornell CLASSE technical notes, cross-checked against the sample pages of ISO 1609:1986; numbers for ISO-K and the centering ring, bolt-pattern templates for ISO-F as files
- Page: https://xemstudio.com/objects/iso-k-iso-f-flanges-dn63-dn630/ · JSON: https://xemstudio.com/api/geometry?object=iso-k-iso-f-flanges-dn63-dn630 · Plain text: https://xemstudio.com/objects/iso-k-iso-f-flanges-dn63-dn630/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 750.0 | 750.0 | 6.0 |

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- ISO-K and ISO-F (also LF, 'large flange', or ISO 1609) are the large vacuum flanges: ISO-K flanges are joined with clamps and ISO-F flanges with bolts through holes on a bolt circle. Both use a centering ring with an O-ring. Sizes are named by nominal bore in mm: 63, 80, 100, 160, 200, 250, 320, 400, 500, 630.
- All values mm. ISO-F: flange OD, number of holes, hole diameter and bolt circle (BCD) are from the Lesker table (inches there, given with mm: 130 / 145 / 165 / 225 / 285 / 335 / 425 / 510 / 610 / 750 mm OD; BCD 110 / 125 / 145 / 200 / 260 / 310 / 395 / 480 / 580 / 720 mm; holes 4, 8, 8, 8, 12, 12, 12, 16, 16, 20; hole Ø 9, 9, 9, 11, 11, 11, 14, 14, 14, 14 mm; bolts M8 to M12 as printed '5/16 (M8)', '3/8 (M10)', '1/2 (M12)'). ISO-K flange OD is 95, 110, 130, 180, 240, 290, 370, 450, 550, 690 mm.
- Cross-check against the standard: the OCR'd sample of ISO 1609:1986 (bolted flanges, nominal bore 200 to 1000, headers partly unreadable) repeats the same numbers for 200 to 630: 285 / 335 / 425 / 510 / 610 / 750 (outside diameter), 260 / 310 / 395 / 480 / 580 / 720 (bolt circle), 12 / 12 / 12 / 16 / 16 / 20 (holes), 240 / 290 / 370 / 450 / 550 / 690 (K flange OD) and 213 / 261 / 318 / 400 / 501 / 651 (centering ring lip OD). The sample's other columns (c, Y, D, M) cannot be assigned from the garbled headers and are not used, so hole diameter and bolt size above are Lesker's only.
- Centering ring lip OD and ID (Lesker, mm): the lip OD fits the flange recess. ISO 1609 also gives 800 and 1000 bolted flanges and recommends 1250 to 2500; these are not on the Lesker table read and are not covered here.
- Files: ISO-F bolt-pattern templates, one per size: a disc of the flange OD with the published hole count, hole diameter and bolt circle. Thickness (6 mm), the central aperture (half the bolt circle) and the position of the first hole (on +X) are Xem choices; the hole orientation relative to the sealing axis is not given by the sources. The collar, recess and sealing face are not modelled (no published numbers read). ISO-K clamp flanges are not drawn: their clamp seat is not dimensioned in the sources read.
- Small flanges are on iso-kf-flanges-nw10-nw50 and knife-edge flanges on conflat-cf-flanges. McMaster-Carr's vacuum-fittings category is linked for per-part STEP.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| ISO-F bolt holes | DN63: 4 × Ø9 on Ø110; DN80: 8 × Ø9 on Ø125; DN100: 8 × Ø9 on Ø145; DN160: 8 × Ø11 on Ø200; DN200 / 250: 12 × Ø11 on Ø260 / Ø310; DN320: 12 × Ø14 on Ø395; DN400 / 500: 16 × Ø14 on Ø480 / Ø580; DN630: 20 × Ø14 on Ø720 | M8 (DN63-100), M10 (DN160-250) or M12 (DN320-630) bolts through the mating ISO-F flange's identical pattern (Lesker table) | slide | iso-f-bolt-pattern* |
| centering ring lip OD | Ø70 (DN63), 83, 102, 153, 213, 261, 318, 400, 501, Ø651 (DN630) (Lesker; ISO 1609 sample repeats 213 to 651) | flange recess that locates the centering ring with its O-ring | slide | all |

## Sizes

| size | ISO-K flange OD | ISO-F flange OD | ISO-F bolt circle | ISO-F holes | hole Ø | bolt | centering ring lip OD | lip ID |
|---|---|---|---|---|---|---|---|---|
| DN63 | 95 | 130 | 110 | 4 | 9 | M8 (bolt 5/16 in) | 70 | 66.8 |
| DN80 | 110 | 145 | 125 | 8 | 9 | M8 (bolt 5/16 in) | 83 | 79.8 |
| DN100 | 130 | 165 | 145 | 8 | 9 | M8 (bolt 5/16 in) | 102 | 98.8 |
| DN160 | 180 | 225 | 200 | 8 | 11 | M10 (bolt 3/8 in) | 153 | 149.9 |
| DN200 | 240 | 285 | 260 | 12 | 11 | M10 (bolt 3/8 in) | 213 | 209.8 |
| DN250 | 290 | 335 | 310 | 12 | 11 | M10 (bolt 3/8 in) | 261 | 257.6 |
| DN320 | 370 | 425 | 395 | 12 | 14 | M12 (bolt 1/2 in) | 318 | 312.4 |
| DN400 | 450 | 510 | 480 | 16 | 14 | M12 (bolt 1/2 in) | 400 | 394.5 |
| DN500 | 550 | 610 | 580 | 16 | 14 | M12 (bolt 1/2 in) | 501 | 495.6 |
| DN630 | 690 | 750 | 720 | 20 | 14 | M12 (bolt 1/2 in) | 651 | 645.4 |

## Where the files are

- Cornell CLASSE (technical notes, reproducing Kurt J. Lesker ISO tables): [ISO flanges technical notes: ISO-F flange OD, holes, bolt circle, bolts; ISO-K flange OD; centering ring lip OD and ID, sizes 63 to 630](https://www.classe.cornell.edu/~dms79/D-lineNotes/components/ISO%20Flanges-TechnicalNotes.htm) — web — Lab technical notes; numbers only
- ISO (iTeh preview): [ISO 1609:1986 Vacuum technology - Flange dimensions (sample pages, OCR with garbled headers): bolted flange rows for nominal bores 200 to 1000](https://cdn.standards.iteh.ai/samples/6209/2492d409536f44d6865afcbaaf717433/ISO-1609-1986.pdf) — web — Standard preview; numbers only; headers partly unreadable
- ANCORP (catalogue): [ISO quick flange (QF/KF) and large flange (LF) centering rings: ID cross-reference, A and B dimensions in inches (stainless and aluminium centering ring assemblies)](https://future4200.com/uploads/short-url/aRKA89A8sSu693NTJW9PFqCukFa.pdf) — web — Maker catalogue; numbers only
- Kurt J. Lesker (catalogue, extracted text): [Flanges, fittings and components: CF fixed flange standard dimensions (bolts, hole diameter, tapped thread, bolt circle); size lists for KF 1-4 and ISO 1-5](https://www.acomee.com.mx/catalogos/catalogosk/KURT-J-LESKER FLANGES, FITTINGS AND COMPONENTS.pdf) — web — Maker catalogue copy; numbers only. Column letters were not labelled in the extracted text
- McMaster-Carr: [Vacuum fittings (KF / ISO flanges) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/vacuum-fittings/) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Questions

**What is the bolt circle of an ISO-F DN100 flange?**

145 mm: 8 holes of Ø9 for M8 bolts, flange OD 165 mm.

**What is the OD of an ISO-K DN160 flange?**

180 mm (the ISO-F DN160 flange is 225 mm OD, 8 × Ø11 holes on a 200 mm bolt circle).

**What is the difference between ISO-K and ISO-F?**

ISO-K is clamped over a tapered back; ISO-F is bolted through holes on a bolt circle. Both seal with a centering ring.

## Fits with

- [ISO-KF (NW, QF) small flanges to ISO 2861: flange OD, bore, O-ring and centering ring, KF10 to KF50](https://xemstudio.com/objects/iso-kf-flanges-nw10-nw50/)
- [ConFlat (CF) knife-edge vacuum flanges to ISO 3669: flange OD, bolt circle, hole count and diameter, thickness, tapped thread, 1.33 to 8 in + bolt-pattern templates](https://xemstudio.com/objects/conflat-cf-flanges/)
- [ASME B16.5 Class 150 pipe flanges, NPS ½ to 24: dimensions, bolt circle, slip-on and blind](https://xemstudio.com/objects/asme-b16-5-class-150-flanges/)
- [ASME B16.5 flange bolt patterns: bolt circle, number of holes and bolt size, Class 150 and 300, NPS ½ to 24](https://xemstudio.com/objects/asme-b16-5-flange-bolt-patterns/)
- [Camlock (cam and groove) couplings: types A, B, C, D, E, F, DC, DP, 1/2 to 4 in sizes, adapter flange diameter](https://xemstudio.com/objects/camlock-couplings/)
- [Metabo vacuum hose sizes: hose ID / OD, connection OD, Quick Ø32 coupling bush](https://xemstudio.com/objects/metabo-vacuum-hose-sizes/)