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  Published on Monday, March 5, 2018

Membrane solutions

Fixed and interchangeable membrane

Fixed membrane

CIMM offers a wide range of membrane tanks suitable to any purpose together with custom made solutions, being specialized in the production of expansion tanks with interchangeable membranes and fixed diaphragms. Always made in accordance to the industry regulations in force, both membrane models, whether them being interchangeable or fixed, are validated by decades of R&D studies and therefore can be used for all intended purposes.

CIMM, thanks to its know-how, takes full advantage of the characteristics of the different types of membranes, knowing how to maximize efficiency from the beginning - during the installation process, according to the size of the vessels – to the end, so that these may always work in optimal conditions without being particularly stressed. Almost all of CIMM’s expansion vessels used in heating systems for boilers are flat vessels (circular or rectangular) with a fixed membrane (or diaphragm).

Their excellent performance in a boiler is granted by the smaller area of the diaphragm membrane, which prolongs the vessel pre-charged pressure over time. Furthermore, during the work cycles, the fixed membranes only perform a translational movement, which means that they are not subject to stretching or to decrease in thickness, and this greatly increases their average lifespan.

Here are the advantages of the fixed diaphragm membrane used in CIMM expansion vessels for heating systems:

  • Excellent performance of such products in heating systems;
  • Increased maximum length of pre-charge with high temperatures;
  • Elimination of stretching and thinning of the rubber thickness;
  • Increased lifetime of the membrane.


Interchangeable membrane

CIMM chooses to build the tanks used in sanitary systems with interchangeable (or balloon-shaped) membranes, as these increase the vessel performance and the energy savings. By reducing the water accumulation inside the expansion tank, the interchangeable membrane prevents the water to come in contact with the vessel’s metal parts, removing any corrosive phenomena, and avoiding any risk of water contamination and possible proliferation of harmful bacteria.

As an additional protection, CIMM S.p.A. always installs a polypropylene cap, which is approved for domestic use, on the counterflange.

To summarize, here are the advantages of the interchangeable membranes used in CIMM expansion vessels for sanitary water systems:

  • Increased vessel performance;
  • Maximum discharge capacity of water;
  • Significant reduction of energy consumption;
  • Easily replaceable;
  • Elimination of contamination risks, since the water never comes in contact with the tank’s metal parts;
  • Elimination of possible corrosion;
  • The PP cover provides a further protection against corrosion and oxidation;
  • Elimination of the drinking water contamination risk;
  • Increased membrane and tank lifespan.