We all understand the phrase “In a perfect world….” used to describe a hypothetical scenario that is unlikely to happen. This phrase is helpful for understanding the variability in oxygen readings measured and displayed when using the 9101 series Bridge analyzers powered by luminescence oxygen sensors. While the lab standard for dry air oxygen is 20.95%, this is based on 1013 mbar barometric pressure, 0% humidity, and 0°C.
For example, when oxygen is measured at ~5 mbar lower barometric pressure due to elevation, at 24° C, and at normal humidity the luminescence sensor in the Bridge analyzer measures 19.6% oxygen. The sensor reading is correct. It is important to understand the following:
• Real indoor air is very likely to measure 19.5 – 20.2% oxygen.
• A reading of 19.6% or something else in this range is to be expected.
• The real dry-air equivalent of this 19.6% reading is, in fact, 20.9%. No oxygen deficiency is present.
The oxygen sensor in the 9101 series analyzers from Bridge fundamentally measures oxygen partial pressure. When it reports the percent oxygen, it will back calculate using measured barometric pressure.
This physics-based method provides long reliable sensor life and offers a next generation measurement method over the traditional electrochemical-based sensors.