Introduction to Oxygen (O2) Deficiency

Oxygen (O2) deficiency is a hazardous condition in many plants and buildings. The air we breathe is 20.9% Oxygen by volume, and a human being cannot function properly if the Oxygen concentration falls below this level. Oxygen deficiency can occur in confined spaces such as manholes, tunnels, pipelines, storage tanks, and underground vaults. Often a benign gas, such as nitrogen, would not be a hazardous gas. However, if that gas pushes Oxygen out of the space, then Oxygen deficiency becomes the hazard.

Health Hazards

When Oxygen levels drop to hazardous conditions, these symptoms may be produced:

  • Headache
  • Dizziness
  • Fatigue
  • Impairment
  • Vomiting
  • Loss of consciousness
  • Death

Oxygen Deficiency Limits

When researching O2 gas detection solutions, facility managers should be aware of the following O2 deficiency hazard limits:

Oxygen Deficiency Hazard O2 in Air
Normal oxygen concentration 20.9%
Oxygen deficient Below 19.5%
Unsafe for humans Below 16%

Technology for O2 Deficiency Detection

Electrochemical Sensors

Electrochemical sensors are fuel cell-like devices consisting of an anode, cathode, and electrolyte. The components of the cell are selected so that a subject gas, allowed to diffuse into the cell, will cause a chemical reaction and generate a current. The cells are diffusion-limited, meaning that the rate of the gas entering the cell is solely dependent on the gas concentration. The current generated is proportional to the rate of consumption of the subject gas in the cell.

Learn more about the advantages of using Sierra Monitor's electrochemical gas sensor modules »