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Rosahl is the world’s smallest electric dehumidifier. This page provides an introduction to the products, their benefits, and how to use them.


What is Rosahl?

Rosahl is a unique electric micro-dehumidifier for enclosures where maintenance-free drying is an important factor. It uses a solid polymer membrane (SPE) installed in a flat panel. A range of membrane sizes is available for enclosures volumes from one litre up to 4m³ (140 cu ft.) in volume. The MDL-5 membrane for drying an enclosure up to 1m³ measures only 88 x 88 x 2.3 mm

See product overview


Where are Rosahl micro-dehumidifiers used?

The Mitsubishi Electric Corporation in Japan developed Rosahl. It was in response to demand for compact and maintenance free air-drying solutions to protect sensitive equipment from moisture damage. It has since found its way into a wide range of other uses. These include for protecting museum display cabinets, telecoms. equipment, LED lighting, lasers, instrumentation and electrical cabinets and more.

Rosahl membranes fit a wide variety of applications and environments from -20° to +50° C


How do membrane dehumidifiers work?

Rosahl dehumidifiers work by electrolysis when supplied from a suitable 3V D.C. power supply. They act like an ionic pump to remove water vapour at a molecular level, without involving liquid water.

Importantly, no liquid water means no cleaning, no draining and no maintenance. With low running costs, they are suitable for use in remote locations, and where a conventional dehumidifier is difficult to maintain or to service.

Go here to see how they work


Why use Rosahl?

Designed for industrial and commercial applications, Rosahl membranes offer a long-term solution to humidity control for enclosures.

Applications range from storage areas for sensitive equipment through to challenging or remote external environments, and many other uses.  Rosahl is a low energy moisture extraction system and has a low capacity relative to larger conventional (condensing) dehumidifiers. The process does not involve liquid water. So, unlike condensing humidifiers, they require no cleaning or draining: unlike silica gel, they do not require regular recharging or replacement.

ROSAHL products consume very little energy compared to other types of humidification. This means they will run 24 hours a day, 365 days a year, continuously extracting moisture from an enclosed area without incurring major energy costs. Because they are maintenance free, they will continue working for years without concern. This means no servicing and lower cost of ownership (TCO).

See a summary of Rosahl’s features and benefits

Installing Rosahl membranes

The manufacturer recommends mounting the dehumidifier over a cut-out at the mid-point of the enclosure’s vertical side panel. This is because moist air is less dense than dry air. Basic installation information is  given in the accessory and installation page.

See the product user guides in the documentation section for more information.


Selecting Rosahl

Using Rosahl membranes to dehumidify an enclosure or cabinet is a simple process and starts with selection of the module type.  The main requirement is knowing the ambient and target humidity, enclosure size and sealing.

See Rosahl selection guide

Suitable power supplies are also available.

Typical Rosahl Applications

  • Traffic control and display cabinets
  • Outdoor multimedia screens and displays
  • Mobile telecommunications outstations
  • Precision equipment storage cabinets
  • Museum displays and exhibition cabinets
  • Protecting sensitive opto and electronic devices
  • Storage of hygroscopic materials
  • Semiconductor manufacturing
  • Infrared spectrographs
  • External LED lighting
  • Laser cabinets
Rosahl flat panel dehumidifier
Rosahl dehumidifier membrane compared to AA battery

Benefits of Rosahl

ROSAHL dehumidifiers are:

  • Silent and vibration free so they can be used virtually anywhere
  • Maintenance free to reduce lifetime operating costs
  • Drain-less, so no water removal or cleaning is required
  • Ultra-compact, devices will fit almost any enclosure
  • Environmentally friendly design with low power consumption
  • Long operating life
  • Available also for use as humidifiers or for balancing precious environments
  • Suitable for remote locations and where servicing is difficult or expensive


Factory Quality Standards

ISO 9001 Certified

ISO 14001 Certified







Westside International Ltd

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