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 moisture in a cabinet changes. The drying curves published by the manufacturer reflect this information.
Drying curves for Rosahl dehumidifying membranes
Absolute dehumidifying capacity
As an example, a size 10 membrane M-10J1R. The published capacity of this device is 29g/day. This assumes ambient conditions of 30° C and 60% RH. Under these conditions, the absolute humidity is 18.21g/m3 (from table below).
The M-10J1R membrane capacity of 29g/day changes as temperature and humidity change as follows:
At 30℃・40％RH
Absolute humidity is 12.1g/m3 → 29*(12.1/18.2) =20.2g/day membrane capacity.
At 30℃・90% RH
Absolute humidity is 27.2g/m3 → 29*(27.2/18.2) =44.2g/day membrane capacity.
At 20℃・60％RH
Absolute humidity is 10.4g/m3 → 29*(10.4/18.2) =16.6g/day membrane capacity.
At 40℃・60% RH
Absolute humidity is 30.6g/m3 → 29*(30.6/18.2) =48.8g/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 lower than 30° C the membrane removes less moisture, and when temperature is above 30° C it removes more moisture than the published capacity.
Membrane dehumidifying capacities
| Model | Dehumidifying capacity |
|---|---|
| PD4, PD5 | 42 mg/day |
| PD2, PD3, RD3, RD4 | 84 mg/day |
| RS1, RS2 | 210 mg/day |
| M-1J1R | 1 mg/day |
| M-2J1R | 2 g/day |
| M-3M1R | 2.9 g/day |
| M-3J1R, MDL-3 | 4 g/day |
| M-5J1R, MDL-5, S-5T1 | 9 g/day |
| M-7J1R, MDL7, S-7T1 | 16g /day |
| M-10J1R, S-10T1 | 29 g/day |
Moisture per cubic metre of air
| g/m3 | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% | 100% |
|---|---|---|---|---|---|---|---|---|---|---|
| 50°C | 8.3 | 16.6 | 24.8 | 33.1 | 41.4 | 49.7 | 58 | 66.2 | 74.5 | 82.8 |
| 45°C | 6.5 | 13.1 | 19.6 | 26.1 | 32.6 | 39.2 | 45.7 | 52.2 | 58.7 | 65.3 |
| 40°C | 5.1 | 10.2 | 15.3 | 20.4 | 25.5 | 30.6 | 35.7 | 40.8 | 45.9 | 51 |
| 35°C | 4 | 7.9 | 11.8 | 15.8 | 19.7 | 23.7 | 27.6 | 31.6 | 35.5 | 39.5 |
| 30°C | 3 | 6.1 | 9.1 | 12.1 | 15.1 | 18.2 | 21.2 | 24.2 | 27.2 | 30.3 |
| 25°C | 2.3 | 4.6 | 6.9 | 9.2 | 11.5 | 13.8 | 16.1 | 18.4 | 20.7 | 23 |
| 20°C | 1.7 | 3.5 | 5.2 | 6.9 | 8.6 | 10.4 | 12.1 | 13.8 | 15.5 | 17.2 |
| 15°C | 1.3 | 2.6 | 3.8 | 5.1 | 6.4 | 7.7 | 9 | 10.2 | 11.5 | 12.8 |
| 10°C | 0.9 | 1.9 | 2.8 | 3.8 | 4.7 | 5.6 | 6.6 | 7.5 | 8.4 | 9.4 |
| 5°C | 0.7 | 1.4 | 2 | 2.7 | 3.4 | 4.1 | 4.8 | 5.4 | 6.1 | 6.8 |
| 0°C | 0.5 | 1 | 1.5 | 1.9 | 2.4 | 2.9 | 3.4 | 3.9 | 4.4 | 4.9 |
| -5°C | 0.3 | 0.7 | 1 | 1.4 | 1.7 | 2.1 | 2.4 | 2.7 | 3.1 | 3.4 |
| -10°C | 0.2 | 0.5 | 0.7 | 1 | 1.2 | 1.4 | 1.7 | 1.9 | 2.1 | 2.4 |
| -15°C | 0.2 | 0.3 | 0.5 | 0.6 | 0.8 | 1 | 1.1 | 1.3 | 1.5 | 1.6 |
| -20°C | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.7 | 0.8 | 0.9 | 1 | 1.1 |