Installation Guide for M3M-EMM Rosahl Dehumidifier
Safety and Regulatory Information
For Rosahl M3M-EMM Enclosure dehumidifier
Document No. WSI-INS-22003
Tested to: IEC 62368-1:2018
Manufacturer: Westside International Ltd.
Boston House, Downsview Road, Wantage, OX12 9FF. UK
enquiries@micro-dehumidifier.com www.micro-dehumidifier.com
For correct usage
– Please read this installation guide before installing the dehumidifier. Incorrect use will invalidate the warranty.
General Safety Warnings
- This product is for indoor use only in sealed display or storage enclosures.
- Installation requires the use of tools and technical skills. Not suitable for children or unqualified personnel.
- DO NOT use silicone based sealing materials or they will permanently damage the membrane
- Do not touch, damage, or modify the membrane in any way
- Only use this product with supplied or approved components. Do not substitute the power adapter or modify the membrane or housing. Do not allow the membrane to become wet
- Do not reverse or disconnect wiring, as this will permanently damage the dehumidifier membrane.
- The power adapter includes electronic components sensitive to electrostatic discharge (ESD). Only qualified personnel should remove or service it. –
- Do not use near rust inhibitors, vapour phase corrosion inhibitors or high-density organic gases as they will damage the membrane and reduce performance
Electrical Safety
- Power Input: 5V DC via USB-C (minimum 15W)
- Operating Voltage: 3V DC (regulated via internal adapter)
- The integrated VREG2 adapter includes fold-back current limiting for safe startup.
- Use only with a Class 2 power source or LPS (Limited Power Source) as defined in IEC 62368-1.
- The adapter is not a USB Power Delivery (PD) compliant sink device. Use a standard 5V USB-C power supply if issues occur.
- To disconnect power, simply remove the USB-C plug from the device or switch off the USB power adapter at the source
Environmental Conditions
- Operating temperature: -10°C to +50°C
- Storage temperature: -20°C to +60°C
- Humidity: 10–90% RH (non-condensing)
- Altitude: Up to 2000 m
- Not tested for outdoor use or exposure to liquids.
Maintenance and Servicing
- This product is maintenance-free and contains no user-serviceable parts.
- Do not open, modify, or attempt to clean the membrane or circuit board.
- If the device is damaged or fails to operate, contact the supplier for support or replacement.
Disposal and Recycling
- This product must not be disposed of with regular household waste.
- Dispose of this equipment in accordance with local electronic waste regulations.
- For European customers: This product is covered by the WEEE Directive. Return it to your supplier or designated collection point.
Regulatory Compliance
- Conforms to: IEC 62368-1:2018
- RoHS Declaration: Available
- REACH Declaration: Available
- CE and UKCA marked
- Manufactured in the European Union and Japan (membrane)

Overview and Installation
Dehumidifier Moulds
The M3M-EMM is a dehumidifier for mounting on the outside of an enclosure. Other mounting arrangements are also available. These membrane dehumidifiers are suitable for use with a wide range of sealed display and storage enclosures to protect sensitive and delicate equipment.
The main components are the moulds, a pre-wired power adapter board, the Rosahl membrane and two sealing rings.
When mounted on the outside of a sealed enclosure and connected to a USB-C power supply (not supplied), the dehumidifier expels moisture through the membrane. Installation requires a hole to be made in the enclosure wall through which the moisture is expelled. See below for instructions. The dehumidification process is silent, waterless, maintenance-free and has a low energy footprint.
CAUTION: it is important not to remove or reverse the electrical connections as this will damage the membrane. The dehumidifier membrane needs a 3V DC power source. It receives this from the integrated USB-C power adapter board which reduces the voltage from a standard 15-Watt USB power supply from 5 Volts to 3 Volts A USD power delivery charger (PD) may not be suitable
Assembly & Mounting Instructions
You can mount the dehumidifier vertically or horizontally on the side of the enclosure but ensure the USB connection is in your chosen location.
- Mounting Location
The mounting kit consists of:
– Inner fixture – holds the membrane and USB-C power adapter module.
– Outer cover – secures and protects the assembly.
– Back plate – optional for extra support on flexible enclosure walls.
- Marking and Preparing the Cut-out
– Position loose backplate in the desired location and mark the screw holes.
– Drill one 3.5mm hole first, temporarily bolt the backplate in position. Check the other drill marks are correctly located and using a scribe tool mark the position of the cutout for the vent, then drill the remaining holes.
– Cut the rectangular vent opening using a suitable method. For example, using a Rotary tool with a cutting disk, or manually by drilling a ring of small holes and filing the edges smooth (the installed dehumidifier will cover the cutout)
– Take care not to inhale fumes or dust from the cutting
- Installing Components
Caution: Do not touch the black (internal) or grey (external) membrane surfaces. Wear gloves to prevent damage or contamination.
– Remove the nuts and washers but leave the four screws holding the inner fixtures together, but do not separate the moulds
– Correctly orientate the supplied gasket to the moulds and hold in position with the screws. Note that the fixing holes are offset
– Position the dehumidifier and push the fixing screws through the case and refit the washers and nuts. Do not over tighten the nuts.
– If the enclosure wall is thin or flexible, use the back plate inside the enclosure for a firm seal.
Notes
– Always use the sealing rings to prevent moisture leakage.
– Confirm that the gasket is fully compressed for an airtight seal.
Additional resources
–Additional resources at https://micro-dehumidifier.com/documentation/
– Membrane dehumidifier user manual RB-OP21004 Open PDF
– Membrane RoHS Declaration of Conformity Open PDF
– Membrane REACH Declaration of Conformity Open PDF
– Dehumidifier UKCA/CE Declaration of Conformity Open PDF
– Power adapter board RoHS Declaration of Conformity Open PDF
– Power adapter board REACH Declaration of Conformity Open PDF

Westside-International Ltd
Boston House, Downsview Road, Wantage, Oxfordshire, OX12 9FF. UK