+44 (0)1424 225228 sales@torrscientific.co.uk


Large view diameter viewports become uneconomic to manufacture using the traditional vacuum brazing or induction sealing techniques. It is still possible however to manufacture them using FKM O-rings to make the vacuum seal. An external bolted ring is used to compress the optic against the O-ring forming a leak‑tight seal.

Torr Scientific have manufactured a variety of flange types and sizes with a variety of optics, the most popular materials being Kodial & fused silica. Normal FKM O-rings are bakeable to +150℃, it is also possible to extend the bake-out range to +200℃ using the newer FFKM O-ring materials. A variety of viewports are shown in the photos, they include an ISO160, ISO250, CF250 Conflat, & and an ISO500 (with the lifting eyes) which is the largest viewport Torr Scientific have manufactured to date. The ISO500 viewport was manufactured for Mullard Space Science Laboratory (MSSL) to be used on a large satellite testing vacuum system. The ISO160F & ISO250F fixed bolted flange versions both utilise fused silica optics. They both have 135mm clear view diameters which was a specific customer requirement, the same view diameters can be offered on the claw clamp style ISO flanges as well.

It is possible to supply other optical materials, but please be aware that the optics become considerably more expensive as their diameters and required thicknesses increase. Some of the more exotic materials are not manufactured in these larger sizes. For more information or to ask for a quotation, please contact us at sales@torrscientific.co.uk