Overview
Partial pressure blending
Constant flow blending
Membranes
IT College seminars

The compressor manufacturer must be consulted to assure that the compressor is compatible with 40% blends and the blending method must assure that the blend is completely homogenous when entering the compressor.
The working principle is very easy and many home-made models exist next to the commercially available systems. Because of its simplicity, the initial investment for such a system is low.
Oxygen is injected in a mixing container. Within the container the Enriched Air is “moved” enough to make the mix homogenous. A hose is connecting the mixing container with the compressor and on this hose the Oxygen content is analyzed. Based on the reading on the analyzer, the quantity of injected oxygen can be increased or reduced to achieve the required blend.
The Oxygen needs to be added with a micro metering valve, allowing to set the flow exactly at the intended blend. This valve must have a safety features that prevents settings above 40% oxygen percentage.
The bigger problem is the “mixing container”. The design must assure two important aspects – the mix that exits must be completely homogenous and the container may not increase the resistance for the compressor inlet. The air integrity of the system between the mixing container and the compressor inlet must be 100%.
The big advantage is that the oxygen supply cylinder can be used completely, as the mixing takes place at ambient pressure. This means that one 50 liter cylinder of breathing grade oxygen is good for approximately 40 to 50 filled Enriched Air Cylinders (provided you use mathematics to prevent draining the cylinder before refilling).
There is hardly any additional maintenance cost, the filling goes at the same speed as filling air and the risk of fire and explosion is limited. The only drawback is that the price of each individual fill does not reduce by increasing the number of cylinders filled (normally approx.1 Euro higher than an air fill) – however the price also does not increase either when the number of cylinders filled decreases.

• Mathematics to fill a cylinder without draining residual gas.
• Compressor know-how to prepare and maintain the compressor to deliver oxygen compatible air and to assure the compressor inlet does not experience resistance.
• System set-up, safety features and maintenance.

All these aspects are covered in the special IT College seminar