Diaphragm seals

Diaphragm seals are used for pressure measurement when the medium must not come into contact with the pressure-bearing parts of the pressure measuring instrument. The diaphragm seal - a process connection with a separating diaphragm - separates the measuring instrument from the medium with an elastic diaphragm and transfers the pressure to the measuring instrument. The inner space between the diaphragm and the pressure measuring instrument is completely filled with a pressure transmission fluid. If pressure is generated from the medium, the pressure is transmitted via the elastic diaphragm to the liquid and further to the measuring device.

If measuring instruments are connected to the process via a diaphragm seal, the most difficult measuring tasks can be realised. Diaphragm seals are used in conjunction with Bourdon tube pressure gauges, pressure switches, transmitters and differential pressure transmitters.

Optimum diaphragm seal designs, materials and filling media are available for every application. Diaphragm seals are manufactured with screw, flange, clamp connections and milk pipe screw connections with union nut or threaded connection. The dead-space-free diaphragm seals with flush diaphragms are particularly popular in the food and pharmaceutical sectors, as they ensure a hygienic and sterile process. Measuring units with diaphragm seals can be easily dismantled for cleaning or calibration.

The various combinations allow pressure ranges from -1 bar...1'000 bar even at extreme temperatures of -90 °C...+400 °C. A great advantage of measuring units with diaphragm seals is that the medium acts on the diaphragm over a large area. This makes accurate pressure measurement possible, especially at very low pressures < 600 mbar. Diaphragm seals are suitable for aggressive, corrosive, abrasive, highly viscous, heterogeneous, toxic or aseptic media. To protect against corrosion in aggressive media, the diaphragm is coated or made of special materials.