Air, nitrogen dioxide and oxygen are common oxidants. If, for example, oxygen is not handled properly, the ambient atmosphere becomes enriched with oxygen. The information below details the dangers of enrichment and the simple measures required for safe handling of oxygen.
Atmospheric gases are not toxic. If their concentration increases, they can have an impact on life and a combustion process (especially for oxygen). A sufficient supply of oxygen must be present in the breathable atmospheres.
Oxygen itself is not flammable, but it maintains combustion. In contrast, nitrogen and argon inhibit combustion. Changes in the concentration of these gases cannot be detected naturally by humans. If these gases are not used appropriately, accidents can occur.
In order to be stored in liquid form, these gases must be cooled to an extremely low temperature (below -180 ° C, at atmospheric pressure). In this state, they can quickly cause cold burns and make some materials brittle, which can result in structural failure.
Risk of fire due to oxygen enrichment
Oxygen reacts with most elements. The starting, speed, strength and extent of these reactions depend on a number of factors, including:
- The concentration, temperature and pressure of these reagents
- The combustion energy and the ignition mode.
Flammability of materials
The risk of fire increases considerably when the concentration of oxygen in the atmosphere increases, even if it is only a few percentage points. Sparks, which normally would be safe, can cause fires in oxygen-enriched atmospheres, and materials that would not normally burn in the air – including fireproof materials – can burn vigorously, even spontaneously.
Hydrocarbons and grease
Oil and grease are particularly dangerous in the presence of pure oxygen because they can be consumed spontaneously and burn with explosive violence. They should never be used to lubricate oxygen or enriched air equipment (special lubricants compatible with oxygen may be used under certain conditions).
Many combustion accidents are due to cigarette ignition in oxygen-enriched atmospheres. Smoking in oxygen enriched atmospheres or in places where oxygen enrichment is possible, represents an extremely high risk. It must absolutely be forbidden to smoke in such places.