Oxygen Depletion

A most common form of detection is for Oxygen depletion or Oxygen enrichment. Most laboratories fitted with EG a Nitrogen or Carbon Dioxide supply are equipped with an Oxygen depletion detector. The normal concentration of oxygen in the atmosphere is approximately 20.9% by volume.

Oxygen levels may be depleted due lack of ventilation or due to dilution by other gases such as carbon dioxide, nitrogen or helium. Oxygen sensors should be used in environments where any of these potential risks exist.

CO2 Detection Using an Oxygen Detector?

A common misunderstanding is using an Oxygen detector to detect leaks of Carbon Dioxide. To illustrate the risk doing so, please refer to the table below.

CO2OxygenNitrogenOther Gases
0%21.00%78.00%1%
1%20.80%77.20%1%
2%20.60%76.40%1%
3%20.40%75.70%1%
4%20.20%74.90%1%
5%20.00%74.10%1%
6%19.70%73.30%0.90%
7%19.50%72.50%0.90%
8%19.30%71.80%0.90%
9%19.10%71.00%0.90%
10%18.90%70.20%0.90%

As an example, the pre warning level (TWA) for CO2 is 0.5%. An Oxygen detector would alarm as per Australian standards at 19.5% volume; this would represent a CO2 level of over 7% !! No need to explain the potential risk associated using an Oxygen detector for detection of CO2.

Effects of Oxygen Depletion

Oxygen detectors usually provide a first-level alarm when the oxygen concentration has dropped to 19.5% volume. Most people will begin to behave abnormally when the level reaches 17.5%, and hence a second alarm is usually set at this threshold. Exposure to atmospheres containing between 10% and 13% oxygen can bring about unconsciousness very rapidly; death comes very quickly if the oxygen level drops below 6% volume

Oxygen Enrichment

Increased levels of oxygen (Oxygen Enrichment) may dramatically increase the flammability of any combustible matter. The risk from oxygen enrichment exists where pure oxygen is stored; for example in hospitals and gas manufacturing plants. Very high Oxygen levels over 50% will lead to brain damage.

Oxygen detection system our mostly common at the following applications:

  • At Laboratories
  • Industrial Applications
  • Location with Nitrogen in use
  • Areas with low ventilation