ISO Flanges
ISO Flanges (ISO-LF Large Flange, ISO-LFB Large Flange, Bolted)
ISO flanges are used to form high vacuum connections in 2.5″ (LF63) to 20″ (LF500) diameter vacuum system tubing. ISO flanges are sexless, infinitely rotatable, and fastened with claw clamps or bolts to compress an elastomer O-Ring held in a centering ring between two flange faces to create a high vacuum seal. Two types of ISO flanges with different fastening styles exist. ISO LF flanges, also called ISO-K flanges, use claw clamps secured to an outer rim on the flanges to fasten. ISO LFB flanges, also called ISO-F flanges, use bolts to fasten through bolt holes in the flange.
ISO flange sizes reference the inner diameter in millimeters of vacuum tubing. An ISO flange size chart can be found below.
ISO Flange Size Chart
| ISO Size | Tubing I.D. (mm) | Flange Size | Tubing O.D. (in.) |
|---|---|---|---|
| NW63 | 63 | LF63 | 2.50 |
| NW80 | 80 | LF80 | 3.00 |
| NW100 | 100 | LF100 | 4.00 |
| NW160 | 160 | LF160 | 6.00 |
| NW200 | 200 | LF200 | 8.00 |
| NW250 | 250 | LF250 | 10.00 |
| NW320 | 320 | LF320-1200 | 12.00 |
| NW320 | 320 | LF320-1275 | 12.75 |
| NW400 | 400 | LF400 | 16.00 |
| NW500 | 500 | LF500 | 20.00 |