Diaphragm seals are used for the protection of pressure measuring instruments in applications with difficult media. In diaphragm seal systems, the diaphragm of the diaphragm seal effects the separation of the instrument and the medium. The pressure is transmitted to the measuring instrument via the system fill fluid which is inside the diaphragm seal system. For the implementation of demanding customer applications, there are a wide variety of designs, materials and system fill fluids available. For further technical information on diaphragm seals and diaphragm seal systems see IN 00.06“Application, operating principle, designs”. _{1) Snamprogetti^® is a registered trademark of Saipem S.p.a.}

The model 990.49 diaphragm seal is designed to be screwed into a threaded flange. Due to the extended diaphragm, the diaphragm seal can be used at thick-walled or insulated locations in pipeline and vessel construction. Mounting of the diaphragm seal to the measuring instrument may be made via a direct connection, for high temperatures via a cooling element or via a flexible capillary. For this model, WIKA offers a special steel alloy which is primarily used in the fertiliser industry.