Diaphragm technology uses brine and electricity with a vacuum deposited fiber separator (historically made of asbestos) between the anode and cathode to create chlorine, caustic soda and hydrogen.

This technology has been in use for over a hundred years and is the predominant technology where a salt source is plentiful, for example in North America. 

The two main diaphragm technologies globally were Diamond Shamrock and Hooker, both of whose technology is now contained within the De Nora technology family. Over the years De Nora continued this tradition of innovation by evaluating each component of a diaphragm cell for better performance.


The historical anode in diaphragm cells was graphite.  In the 1970’s, box and then expandable dimensionally stable anodes were introduced which produced the low voltage of a “diaphragm-gap” cell.  De Nora has now developed new alternatives to the standard expandable anodes.  LVA™ anodes offer structural saving of 70mV across the expander. Customers can obtain this same savings by adding a secondary Dublex™ expander to their existing anodes.  ESA™ electrodes have shown an additional power consumption savings when installed in combination with our non-asbestos technology.  Finally, each of De Nora’s facilities can offer full recoating capability with proven manufacturing methods and coatings.


In partnership with our Authorized Suppliers, De Nora offers several different voltage savings cathode choices which have been proven in service for many years.  Among these are the ATC™ Cathodes which utilizes corrugated copper internals and the Bump Plate cathode technology which utilizes either steel or copper voltage saving internals.  In addition, many customers have found they can either save additional voltage or even add capacity by increasing the active area with LCD™ assembly designs. 


The  SM-2® modifier to the asbestos diaphragm was invented to give a much longer life than straight asbestos and with a stable efficiency.  De Nora PMX™ non-asbestos separator uses standard fiber depositing equipment while eliminating asbestos liability.  As a man-made material, performance variability is reduced and a “recipe” can be tailored for the specific brine conditions and desired operating characteristics at specific plants.  These diaphragms can be reclaimed to extend life with average life of over four years and over 11 years of life demonstrated.  Today, there are over 700 diaphragm cells enjoying the advantages of this technology.

Other Components

De Nora continues to look at every component of a cell to reduce operating costs and increase the lifetime.  Examples are the TIBAC™ titanium base covers, PROXIMA® (a registered trademark of Materia Inc.) resins for cell tops and long-life gasket material. 

In addition, we are working to make diaphragm cellrooms safer.  We have extended tests at different sites on a continous wet chlorine hydrogen gas monitor and level monitoring system. 

Let us help find the best solution for your plant.