HYPOXIC OXYGEN DEPLETION
Air is a mixture primarily of two gases – oxygen and nitrogen. Normal air contains 21% oxygen, 78% nitrogen, and 1% of other gases such as carbon dioxide. This combination is kind to both humans and fire. But reducing the oxygen percentage to 16% creates an air mixture that is still kind to humans but is death to most fires. This is the basis of hypoxic fire-prevention systems.
If there is an abundance of nitrogen in the air compared to normal air, then less heat energy is generated due to the decreased oxygen, and more of what is generated is absorbed by heating the nitrogen. At some point of reduced oxygen concentration, the nitrogen overwhelms the oxygen; and a fire cannot continue. It is extinguished.
- No chance of fire is possible in an area containing a reduced oxygen level.
- An on going inert atmosphere is generated.
- The level of oxygen is set for14 –15%as a standard.
- For special fuels may require a different range of oxygen.
- Air with an oxygen content of 5% is injected into the protected room.
- It is not necessary to seal the room tightly but do limit leaks to the room, such as:
- Door and window jambs
- Gaps/cracks and vents
- Wall bypass for electrical installation, pneumatic…
- Minimizing air exchange results into cost savings of the system operation.
- If continuous access is provided, the use of double door systems or curtains is recommended.
- The compressor has to be fed exclusively with external atmosphere air.
- Suitable engineering for the implementation of humidity and temperature control can be designed