Quantity   Component name
1 × Mix Stick Device build from standard plumming parts that mixes oxygen, helium and air using baffles.
1 × Air filter To prevent the entry of foreign matter into the system, an air filter is added to the inlet of the mix stick.
1 × Oxygen sensor A fuel cell type oxygen cell is placed at the end of the mix stick to analyze the gas composition. The analog output of the cell is used to control the oxygen flow by adjusting the needle valve.
1 × Needle valve Flow control device to adjust the amount of oxygen added to gas going the compressor inlet. A stepper motor is added to control the needle valve.
1 × Low pressure regulator Pressure regulator to reduce intermediate pressure to approximately 3 bars. The pressure setting of this regulator determines maximum oxygen flow.
1 × Oxygen first stage regulator To obtain a stable flow rate a regulator is used to reduce the pressure to approximately 10 bars. This is then further reduced by a Festo low pressure regulator.
1 × Oxygen Solonoid A normally closed solonoid is added to the oxygen supply line for safety. In every error mode the oxygen supply will close immediatly.
1 × Microcontroller The whole system is controlled by a microcontroller. During the prototype phase an Arduino is used.
1 × Compressor shutdown relay A normally open safety relay is used to shut down the compressor if an error occurs.
1 × Pelicase Shock proof case to keep components safe.