Rosahl Membrane Selection
Where cabinets are opened, consider the time needed to reduce the humidity to the set-point. If needed, select a larger membrane to reduce the drying period. The expectation is that cabinets using Rosahl dehumidifiers will remain closed for most of the time. Enclosures larger than 4m³, may need more than one Rosahl membrane.
The precise drying time will depend on several variables, like starting and target humidity, air temperature, volume, and leakage area. The following membrane selection tables give an indication of drying times. We recommend undertaking your own tests.
Economy of selection
It is also important to consider the volume of air inside the enclosure rather than the external dimension. For example, if your enclosure is 50% full by volume of non-porous material, then the space volume for dehumidifying is smaller. Finally, try and design your application to ensure you are dehumidifying the smallest volume possible.
Selection
ROSAHL’s dehumidifying capacity (cabinet internal humidity) is determined from the volume of air in the cabinet and its humidity. From the table below, select a suitable model for the volume and target humidity. For example, if your cabinet has a volume of 0.5m³ and your target humidity is 50% then select the M-5J1R or MDL-5 membrane. This table allows for an ambient humidity of up to 90%.
Selection of membrane by volume and target humidity
| For <90% RH ambient | Target humidity 30% RH | Target humidity 50% RH | Target humidity 75% RH |
|
| Membrane selection | ||||
| PD4, PD5 |  | 0.25 l | 0.5 l | 1 l |
| PD2, PD3, RD3, RD4 |  | 0.5 l | 1 l | 2 l |
| RS1, RS2 |  | 1.25 l | 2.5 l | 5 l |
| M-1J1R |  | 30 l | 65 l | 125 l |
| M-2J1R | 60 l | 125 l | 250 l | |
| M-3M1R |  | 90 l | 180 l | 350 l |
| M-3J1R & MDL-3 |  | 0.125 m³ | 0.250 m³ | 0.5 m³ |
| M-5J1R & MDL-5 |  | 0.25 m³ | 0.5 m³ | 1 m³ |
| M-7J1R & MDL-7 |  | 0.5 m³ | 1 m³ | 2 m³ |
| M-10J1R | 1 m³ | 2 m³ | 4 m³ |
Ready to order?
Key Infomation to consider
Drying time curves
The following curves indicate drying performance under defined conditions. The characteristics of the graphs will vary depending on the material in the container and the degree of air-tightness/leakage. If the container contains absorbent material, the membrane induces release of moisture from the material, which may slow dehumidification inside the container. The dehumidifying capacity of the membrane varies according to the absolute water amount inside the container. Changes in the ambient humidity may also affect the performance, and the curves are provided for guidance only.
Typical drying curve for PD4 & PD5 series
Typical drying curve for RD3, RD4 & PD3 series
Typical MDL Series drying curve for a 50 litre container at 30°C 90% RH
Typical M-Series drying curve for a 50 litre container at 30°C 90% RH
Important user notes:
Refer to the user manuals in the documentation section of this site. In addition, please note the following points to help you use Rosahl correctly. If you are in any doubt about the suitability of Rosahl for your application, please contact us.
– Rosahl is not intended as a domestic product and is for installation by a qualified person
– Rosahl is for dehumidifying steady-state (sealed) enclosures or cabinets
– The membranes have a half-life of five years’ operating 24/7 at an average annual operating temperature of 18°C. Half-life declines at higher average operating temperatures. When unpowered, the operating life is unaffected by temperature
– You can increase the effective operating life by over-sizing the membrane, using a humidity controller, or operating at lower average temperature
– The device will be effective from -20° to +50°C (the manufacturer has tested it for storage between -40° C up to +80°C).
– When unpowered, the membranes do not provide a barrier to moisture from entering the enclosure.
– The devices require a power supply of 3V DC with constant current-limiting protection. Some fold-back type PSUs are not suitable. All hiccup mode PSUs are unsuitable.
– Power consumption figures are the expected daily average based on our evaluation
– Do not use silicone rubber sealants unless vulcanised by heat curing, as they may damage membrane and performance.
Refer to the FAQ section or contact us for specific applications. For further information see Membrane Selection
Go here for typical Rosahl user guide
Contact us now and order!
