O-rings for KF and ISO-K flanges
O-ring sizes for KF vacuum flanges
KF system (also known as: Klein Flange, ISO-KF, DN, NW, QF, and other names) is used for low to medium vacuum. DIN 28043 or Pneurop 6606 ISO 2961 Ref: ISO 2861:2013 Vacuum technology – Dimensions of clamped-type quick-release couplings
This is not the same as:
- ISO-K, which is for larger flanges (63 to 250mm diameter) uses multiple claws or clamps to compress the o-ring. ISO-K is defined by ISO 1609/3669, and also DIN 28 404 . Also known as ISO-LF
- CF, aka Conflat or ISO-F, which uses a deformable copper gasket.
- DELTA® or HELICOFLEX® type seal, which uses a “spring-energised” seal, where an outer ductile shell is wrapped around an inner helical spring.
| KF nominal size | I.D. (mm:inch) | Section (mm:inch) | BS 1806 |
|---|---|---|---|
| 10 | 15.24 : 0.60 | 5.334 : 0.210 | 312 |
| 16 | 18.288 : 0.72 | 5.334 : 0.210 | 314~ |
| 25 | 27.94 : 1.10 | 5.334 : 0.210 | 320 |
| 40 | 40.64 : 1.60 | 5.334 : 0.210 | 326 |
| 50 | 53.34 : 2.10 | 5.334 : 0.210 | 330 |
ISO-K flanges:
| DN | ID | section |
|---|---|---|
| 63 | 76 | 5.3 |
| 80 | 88 | 5.3 |
| 100 | 107 | 5.3 |
| 160 | 158 | 5.3 |
| 200 | 209 | 5.3 |
| 250 | 253 | 5.3 |
| 320 | 330 | 7 |