GUS with the mass flow controllers and display screen
GUS has now been greatly improved. In the original version CO2 was mixed into nitrogen and then pressures were balanced and the CO2 doped nitrogen mixed in with the ordinary nitrogen in the air mix. In the new version, just oxygen and nitrogen are mixed to make the synthetic air, then digital pressure regulators are used to bleed in CO2 through capillaries. Much more robust. The O2 content is also measured and the system can regulate that as well. In the Birmingham system, a micro-flow controller regulates CO2 mixing, which also works very well.
