Fumasep FKS-50

Brand: FuMA-Tech
Product Code: 34010005

From $26.00

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Fumasep FKS-50 is a non-reinforced Cation Exchange Membrane (CEM) with very low resistance, high selectivity and high stability in pH acidic and basic environment. The polymer backbone for this membrane is based on a proprietary hydrocarbon resin.

Fumasep FKS-50 membrane comes in either a 10cm x 10cm or 20cm x 30cm size sheet.

Fumatech membranes are highly sensitive to differences in humidity and moisture content. Therefore the membranes can vary +/- 0.5cm from the original cut sizes. Also due to this sensitivity the manufacturer expects wrinkles to form, however soaking the membranes in deionized water will return the membranes to the full size planar state according to the manufacturer.

Fumasep FKS-50 Features:

 • Applications: Designed for Electrodialysis for demineralisation, desalination, capacitive deionization and others.
 • Cation Exchange Membrane
 • Stability range (pH) at 25 ºC: 1 - 14
 • Thickness: 50 micrometers (1.97 mil)
 • Size: 20cm x 30cm

Fumasep FKS-50 Technical Specification Sheet


The membrane is the thin clear foil, delivered on a backing foil (colourless rigid PET foil). Pull off carefully the membrane from the backing foil. The membrane is delivered in dry form.


Keep membrane package closed / sealed when unused. Store, handle and process the membrane in a clean and dust-free area. Use only new and sharp knives or blades, when cutting the membrane. Always wear protective gloves when handling the membrane. Handle with care, be sure not to puncture, crease or scratch the membrane, otherwise leaks will occur. All surfaces in contact with the membrane during handling, inspection, storage and mounting must be smooth and free of sharp projections.


Dry Form: The membrane can be stored dry for an unlimited amount of time. However, the membrane has to be conditioned (washed and rinsed) prior to use.

Wet Form: Storage for short and medium time scale (hours up to several weeks) may be done in unsealed containers in 0.5 - 1.5 wt% NaCl solution or comparable neutral pH electrolytes.  For storage over a longer time period a sealed container is recommended using afore said electrolyte with ca. 100 ppm biocide (NaN3) to avoid biological fouling.

Pre-Treatment and Conditioning:

The membrane is delivered in H+ form and dry form. Depending on application and cell design,assembling is possible in dry form (without pretreatment) or wet form. For optimum performance it is recommended to rinse the membrane in NaCl solution (e.g. 0.5 M NaCl solution at 25°C for 24 hrs) to remove any additive from the membrane. Place the membrane sample between stabilizing meshes / spacers in order to avoid curling. Do not let the membrane dry out since micro-cracks may likely occur during shrinkage.

If you have any concerns about storage, chemical stability and pretreatment before proceeding, please feel free to contact us for further information.

Membrane Properties
Membrane Cation Exchange Membrane
Thickness 45 - 55 µm (microns)
Appearance / Color Transparent / Brown
Backing Foil PET Foil
Delivery Form Dry (non-activated)
Reinforcement None
Counter Ion H-form
Density 7.5 - 8.3 mg•cm-2
Specific Area Resistance 1.8 - 2.5 (in Na+ form) Ω•cm2
Specific Conductivity 2.0 - 3.0 (in Na+ form) mS•cm-1
Selectivity 97 - 99 %
Ion Exchange Capacity 1.2 - 1.4 (in Na+ form) meq•g-1
Dimensional Swelling in H2O at 25°C 0 - 2 %
Uptake in H2O at 25°C 10 - 20 wt %
Bubble Point Test in Water at 25°C > 2.5 bar

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