+44 203 286 8189 steve.jones@westside-int.com

 does Rosahl work?


Rosahl is a unique active dehumidifier that works using a solid state polymer electrolyte (SPE). It removes moisture from the air in enclosures by electrolysis when a small voltage is applied.  It provides clean moisture extraction and low cost, maintenance free performance. The process involves venting the unwanted moisture to the outside through a cut-out in the side of the enclosure.



Sometimes called an ionic membrane dehumidifier, Rosahl works by electrolysis. The SPE consists of a proton-conductive solid polymer electrolyte and porous electrodes with a catalytic layer composed of noble metal particles. When a 3 Volt D.C. charge is applied to the SPE’s porous electrode, the moisture on the anode (dehumidifying) side dissociates into hydrogen ions (H+) and oxygen. The hydrogen ions (not hydrogen gas) migrate through the membrane for discharging on the cathode (moisture discharging) side where they react with oxygen in the air, to form water vapour.

When operating, the density of oxygen in the container increases as the water molecules dissociate into hydrogen ions and oxygen, and the oxygen remains in the container. Due to normal leakage and the occasional opening of the container, the increase in oxygen density is typically 2 to 3%.


Benefits of Rosahl

Rosahl has no moving parts, making it economical to run, silent, and vibration free.  As no liquid water is involved in the process, it is maintenance-free. This makes it suitable for use in remote locations or where servicing is expensive or otherwise difficult. The membrane has a long operating life and an operating temperature range from -10 to +50C. The SPE can also operate as a humidifier by reversing its direction of flow.







Westside International Ltd

Registered in England

Registration No. 4018025

VAT No. 768327395

EIN 98-1234498