Zero Air 5.0 (99.999%). (CO + CO2 < 1 ppm, H2O < 3 ppm, THC < 0.2 ppm, Nox < 0.1 ppm) contains ultra-low levels of impurities making it an ideal zero gas for analytical instrumentation. It is also an ideal detector and/or purge gas for a range of detector types, analytical techniques and processes. Supplied in a 50 litre steel cylinder at 200 bar.