Limiting oxygen concentration
The limiting oxygen concentration (LOC),[1] also known as the minimum oxygen concentration (MOC),[2] is defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. It is expressed in units of volume percent of oxygen. The LOC varies with pressure and temperature. It is also dependent on the type of inert (non-flammable) gas.
| Gas or vapor | Nitrogen / Air | Carbon dioxide / Air |
| Hydrogen | 5 | 5.2 |
| Methane | 12 | 14.5 |
| Ethane | 11 | 13.5 |
| Propane | 11.5 | 14.5 |
n-Butane
|
12 | 14.5 |
| Isobutane | 12 | 15 |
Limiting oxygen concentration for solid materials[4]
| Material | Nitrogen/Air |
|---|---|
PE-HD |
16.0 |
| PP | 16.0 |
| PMMA | 15.9 |
PVC |
16.9 |
PE-LD |
15.9 |
Fir wood |
17.0 |
Corrugated board |
15.0 |
Cardboard palletised |
15.0 |
| Paper | 14.1 |
The effect of increasing the concentration of inert gas can be understood by viewing the inert as thermal ballast that quenches the flame temperature to a level below which the flame cannot exist.[5] Carbon dioxide is therefore more effective than nitrogen due to its higher molar heat capacity.[6]
The concept has important practical use in
The limiting oxygen concentration is a necessary parameter when designing
See also
Sources
Monographs
- Green, Don W.; Robert H. Perry (October 23, 2007). Perry's Chemical Engineers' Handbook. McGraw-Hill Professional; 8 edition. ISBN 978-0-07-142294-9. Chapter 23
- Drysdale, Dougal (1985). An Introduction to Fire Dynamics. Wiley. ISBN 0-471-90613-1.
- W. O. Möller; M. Molnarne; R. Sturm (1998). "Limiting Oxygen Concentration: Recent Results and their Presentation in Chemsafe". Physikalisch-Technische Bundesanstalt (Germany). Retrieved 2009-03-11. (Presented at 9th International Symposium on Loss Prevention and Safety Promotion in the Process Industries, May 1998, Barcelona (Spain))