Fumasep FAA-3-50 is a thin (45–55 µm dry), non-reinforced anion exchange membrane that conducts anions such as OH⁻ or Cl⁻. Unlike proton-conducting Nafion, it is used where anions must be transported in cells running in alkaline or neutral media. It is delivered dry, in the bromide (Br⁻) form, on a PET backing foil, as a 100 × 100 mm sheet.

Compared with its sibling FAA-3-PK-130 it is much thinner and has lower area resistance (0.6–1.5 Ω·cm²), but without reinforcement it is mechanically more delicate. Before use, rinsing in NaCl solution is recommended, and for alkaline electrolysis or fuel cells conversion to the OH⁻ form in NaOH or KOH. Once wet, the membrane must not be allowed to dry out.

Key Features

Thin, non-reinforced anion exchange membrane: dry thickness 45–55 µm (manufacturer data)
Low area resistance: 0.6–1.5 Ω·cm² (Cl⁻ form, manufacturer data)
Ion exchange capacity 1.6–2.1 meq/g; selectivity 92–96% (manufacturer data)
Very low swelling in water (0–2%); stable at pH 0–14 at 25 °C per the maker
Delivered dry, in Br⁻ form on a PET backing foil; can be stored dry for long periods
Conversion to OH⁻ form: at least 24 h in 0.5–1.0 M NaOH or KOH (20–30 °C), then rinse with pure water

Technical Specifications

Membrane type	Anion exchange membrane, non-reinforced
Thickness (dry)	45–55 µm
Backing foil	PET (removed before use)
Ion exchange capacity	1.6–2.1 meq/g (Cl⁻ form)
Area resistance	0.6–1.5 Ω·cm² (Cl⁻ form, 0.5 M NaCl, 25 °C)
Specific conductivity	3–8 mS/cm (Cl⁻ form)
Selectivity	92–96%
Water uptake / swelling	10–25% / 0–2% (25 °C)
pH stability	pH 0–14 (25 °C)
Delivery form	Dry, Br⁻ form
Preparation	Rinse about 24 h in 0.5 M NaCl; convert to OH⁻ form for alkaline use
Size	100 × 100 mm

Applications

Anion exchange membrane (AEM) water electrolysis research (slightly alkaline, 1–2 M solutions)
Alkaline fuel cells, including alkaline direct methanol fuel cells
Electrodialysis, desalination and capacitive deionization
Compartment separator in H-type cells where anion transport is needed