Installation Guide: MD3-COM

Moulded enclosure for Rosahl MDL-3 membrane

The MD3-COM is a three-part mould set for mounting a Rosahl MDL-3 membrane dehumidifier on the outside of an enclosure. It includes an internal sealing ring.

 

Overview

When installed inside a sealed enclosure, the MDL-Series dehumidifier expels moisture through the membrane. Installation requires a cutout in the enclosure wall where the membrane can be mounted to allow moisture removal. The process is silent, waterless, and maintenance-free.

For small or tightly packed enclosures, the membrane can be installed externally. In this case, the MD3-COM enables the unit to draw moisture from inside the enclosure by redirecting the outflow path.

⚠️ Important: Reversing power polarity does not reverse moisture flow. Doing so will damage the membrane. The included mounting kit is designed to maintain correct orientation and function. When combined with the supplied USB-C power adapter, it provides a simple, efficient solution for low-power dry storage.

The membrane kits are suitable for use with a wide range of sealed display and storage enclosures and cabinets to protect sensitive and delicate equipment or devices. Moreover, they are also suitable for applications such as Bambu Lab AMS or other 3D printer filament drying systems, converting them into electric dehumidifiers without ever needing desiccant.

Assembly & Mounting Instructions

 

  1. Mounting Cover Components

The three-part mounting kit consists of:
– The front frame for mounting the MDL-3 and USB-C power adapter module.

– A retaining frame to hold the devices firmly in position and align the gasket that seals the unit.

– A backplate with grille to provide rigidity for dry boxes with flexible enclosure walls.

  1. Marking and Preparing the Cut-out
  1. Before fitting the membrane and power board, position the inner fixture at the desired location and mark the six screw holes.
    2. Drill one hole first and temporarily bolt the fixture in place, then drill the remaining five holes.
    3. Use a 3.5 mm drill bit for mounting holes. The fixture’s holes are slightly oversized to allow for alignment and M3 bolts.
    4. Mark and cut the membrane opening using one of the following or alternative methods:
    –  Use a Dremel style rotary tool with a cutting disk.
    –  Drill a ring of small holes and file to join them up and smooth the edges.
  1. Installing Components

Caution: Do not touch the black (internal) or grey (external) membrane surfaces. Consider wearing powder free gloves to prevent damage or contamination.

1.  Install the USB-C power module into the inner fixture. Ensure the cable and USB-C socket align with the exit holes and push the board firmly into place.

2. Carefully connect the power module to the MDL-3 membrane. The red wire to the positive (+) terminal and black to the negative (-). The terminals are of different sizes to prevent incorrect polarity—do not force or reverse them.

3. Correctly orientate the MDL-3 membrane with the lettering, terminal marking, and black face visible. Then position the membrane between the mounting pegs.

*If the lettering and terminal markings are face down
the membrane will humidity the enclosure
  1. Slide the inner cover into position. The small notch at the top of the inner outer cover should be at the power supply end of the assembly near the power adapter board.
  2. Insert the gasket into the slot in the retaining frame with the flat side against the MDL-3 membrane.

Final Mounting

  1. Position the assembled unit over the enclosure cut-out.
  2. Fix to the dry box wall using the nuts and bolts or use the M-5PKT kit.
  3. If the dry box wall is thin or flexible, use the backplate inside the enclosure for a firm seal. Position it so that the full membrane surface is visible-the mounting bolts will hold it in place! Otherwise discard it.

Parts List

– MD3-COM inner + outer mounting fixture
– Rectangular rubber seal
– Backplate (use optional
– Fixing screw kit M-5PKT

Additional parts needed

– MDL-3 membrane
– Pre-wired USB-C power supply adapter (VRD-330)
– Fixing screw kit M-5PKT

Notes

– Ensure all electrical connections are correct before final assembly.
– Always use the seal to prevent moisture leakage.
– Confirm that the gasket is fully compressed for an airtight seal.
– Illustrations are for guidance only.
– Version 1.C1