Oxygen Enrichment
Oxygen enrichment refers to air containing more than 23.5 percent oxygen. This dangerous condition is an extreme fire hazard in which static electricity from materials such as hair or clothing can provide the ignition source needed to start a fire. This environment also allows any fire to burn more readily. Oxygen enrichment does not occur naturally and should be investigated.
Oxygen enrichment can be caused by leaking oxygen cylinders or hoses that have been brought into or near the space. Always ventilate confined spaces with normal, ambient air. Never use pure oxygen.
Combustible and Flammable Atmospheres
Atmospheres containing combustible dust, or combustible /flammable gases or vapors can be dangerous because of the threat of fire or explosion.
The "fire triangle" illustrates the three primary ingredients necessary for an atmosphere to become flammable:
- an ignition source (heat or flame),
- fuel (combustible gas or vapor), and
- oxygen.
The Fire Triangle
Two additional ingredients also contribute to the potential for an explosion:
- Dispersion describes how the dust, gas or vapor may be dispersed throughout the confined space. The potential for explosion may not exist in one area of the confined space, yet and explosion might be likely in another area.
- Confinement keeps the dust, gas or vapor from being adequately dispersed. Force air ventilation is critical to ensure confinement to dangerous levels does not occur.
However, the proportions of fuel and oxygen in a mixture must be within the flammable range for this mixture to be readily ignitable.
Knowledge Check Choose the best answer for the question.
2-4. What are the three components of the fire triangle?
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