Diaphragm seals, also known as chemical seals, isolate pressure-measuring instruments from the process media. The system pressure is transmitted to fill fluid through the diaphragm seal, and from there to the pressure-measuring instrument itself.


Choosing the right diaphragm seal depends on a number of factors. You must consider process characteristics such as temperature extremes or whether the media is corrosive, viscous, toxic, abrasive or contains suspended solids. The fill fluid must be chemically compatible with the process fluid in the unlikely event of a diaphragm rupture. You need to consider the transmitter sensor range, mounting position, regulatory requirements and other criteria.

Among its customers, Badotherm enjoys close contacts with some of the most demanding companies in the process industry. Summer 2008, Badotherm was requested by a resin manufacturer in Holland to take on the challenge of supplying a series of chemical seals to protect against hydrogen diffusion whilst respecting the company’s strict requirements for specific high temperature / high pressure process connections.

We need a safe, reliable and accurate measurement of high pressure media containing hydrogen.

The result: A Yokogawa EJX series pressure transmitter combined with a Badotherm unique 40µm gold plated diaphragm seal suitable for high pressure Destec coupling mounting. This solution will result in cost saving due to the more compact design compared to API flanges.