The oxygen membrane separates N2 out of the breathing air, thereby increasing the oxygen content. The oxygen content in the breathing air can be freely regulated between 21% and 40% (lower and upper limit values). The efficiency of the membrane is determined by temperature.
Therefore, to maximise the efficiency of N2/O2 separation and for constant gas composition, the air compressed upstream is temperature-controlled to a constant 20°C in a refrigeration dryer before being fed into the membrane. This ensures that the set percentage O2 content of the nitrox mixture remains constant.
When the air flows through the hollow fibres of the membrane in a longitudinal direction, most of the oxygen molecules and some of the nitrogen molecules penetrate its wall, transverse to the main direction of flow.
The more the gas flow is restricted at the membrane outlet, the more nitrogen molecules are pushed through the wall together with the oxygen molecules, thus reducing the oxygen content in the gas mixture.
This method enables the oxygen in the breathing air to be enriched by a maximum of 40%.
The oxygen content in the breathing air is maximised when the gas is able to flow freely and without restriction; as a result, the air quantity generated by the LOW PRESSURE MODULE is maximised at the same time.