These types of diaphragm seals are designed for either direct mounting on the process flange or by clamping the seal between process flange and a cover flange. They are available in all kind of international flange standards, ASME B16.5, EN1092-1, API 6A ISO 10423 or JIS B2220.

The BF construction has a seal body that is made of a blind flange. The weld of the diaphragm to the seal body is a wetted part and therefore diaphragm materials are mostly chosen the same as the flange material. The BF is typically used in combination with (differential) pressure transmitters for applications such as level, flow and (absolute) pressure measurement.