WIKA Diaphragm Seal with Flange Connection (990.29)

Flange-type with extended diaphragm


  • Aggressive, highly viscous, crystallising or hot media
  • Process industry
  • Thick-walled or insulated pipelines and vessels

Special Features

  • Flange with extended welded diaphragm
  • Common standards and nominal widths available
  • When special materials are selected, all wetted parts are made of the selected material
  • Robust, all welded design

Sales Contact (Wika.sales@asyatrafo.com)




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”.

The model 990.29 diaphragm seal is available in place of a blind flange for all commonly used standard flanges. Due to the extended diaphragm (tube version), the diaphragm seal can be used at thick-walled or insulated locations in pipeline and vessel construction. Assembly 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 the material selection WIKA offers a variety of solutions, in which the upper body of the diaphragm seal, the extended diaphragm and the wetted parts can be made of identical or different materials. The diaphragm and the extended diaphragm can, as an alternative, be coated.