Various mixes of oxygen, nitrogen and helium are used as breathing gas for recreational diving. One way of blending these gas mixes is by using a continuous mixing method where oxygen and helium are added to plain atmospheric air at the inlet of a high pressure compressor. By measuring oxygen content at the inlet and regulating oxygen and helium flow using motorized needle valves the proper mix is created. The project is started with an oxygen control system, helium is added once the oxygen system is fully functional and tested. Safety features for gas and compressor shutdown are all included in one mobile case.
More details and progress will follow shortly.
Device build from standard plumming parts that mixes oxygen, helium and air using baffles.
To prevent the entry of foreign matter into the system, an air filter is added to the inlet of the mix stick.
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.
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.
Low pressure regulator
Pressure regulator to reduce intermediate pressure to approximately 3 bars. The pressure setting of this regulator determines maximum oxygen flow.
Spring is here :) Time to get this page moving again soon. Still loads of other projects, but also found a compressor and other parts to get this project going. It might become a 2-step project though, as a wall-mounted system is more easy to optimize before building the mobile version..