Is the absolute dehumidifying capacity affected by ambient temperature and humidity?
Rosahl membranes remove moisture from an enclosure. The manufacturer publishes dehumidifying capacity at 30° C and 60% RH as an indication of performance. This is not the absolute dehumidifying capacity of the membrane
Exactly how much moisture they remove depends on the temperature and absolute humidity (g/m³) in the enclosure. The capacity changes as the absolute moisture in a cabinet changes. This information is reflected in the drying curves published by the manufacturer
Drying curves for Rosahl dehimidifying membranes
Absolute dehumidifying capacity
As an example, we consider a size 10 membrane M-10J1R. The published capacity of this device is 29g/day. This is based on ambient conditions of 30° C and 60% RH. Under these conditions, the absolute humidity is 19.1g/m3 (from tables)
The M-10J1R membrane capacity of 29g/day changes as temperature and humidity change as follows:
At 30℃・40％RH
Absolute moisture is 12.7g/m3 → 29*(12.7/19.1) =19.3g/day membrane capacity
At 30℃・90% RH
Absolute moisture is 28.6g/m3 → 29*(28.6/19.1) =43.4g/day membrane capacity
At 20℃・60％RH
Absolute moisture is 10.5g/m3 → 29*(10.5/19.1) =15.9g/day membrane capacity
At 40℃・60% RH
Absolute moisture is 33.2g/m3 → 29*(33.2/19.1) =50.4g/day membrane capacity
Summary
At 30℃, when RH is higher than 60% the membrane will remove more moisture, and when RH is less than 60% it removes less moisture than the published capacity
At 60% RH, when temperature is lowerer than 30° C the membrane removes less moisture, and when temperature is above 30° C it removes more moisture than the published capacity
| Model | Dehumidifying capacity* | |
|---|---|---|
| PD4/PD5 | 42 mg/day | |
| PD2/PD3/RD3/RD4 | 84 mg/day | |
| M-2J1R | 2g /day | |
| M-3M1R | 2.9g /day | |
| M-3J1R/MDL-3 | 4g /day | |
| M-5J1R/MDL-5 S-5J1/S-5T1 | 8g /day | |
| M-7J1R/MDL-7 S-7J1/S-7T1 | 16g /day | |
| M-10J1R S-10J1/S-10T1 | 29g /day | |
| * Initial dehumidifying capacity of a new membrane at 30C and 60% RH | ||