LIMITED OXYGEN CONCENTRATION (LOC)
BS EN 14034 part 4
The limiting oxygen concentration test is conducted to determine the minimum quantity of oxygen, within an atmosphere, that will enable a powder dispersed in air, as a dust cloud to ignite. Working through a range of powder concentrations, the powder is dispersed into a 20L explosion vessel (sphere) using, dry compressed air and nitrogen. Using partial pressures the oxygen content within the sphere at the time of ignition can be controlled. These suspended dust clouds are then exposed to a large 2 kJ chemical ignition source and any ignition and following explosion is monitored, measured and recorded. The oxygen concentration is reduced until ignition is not possible and the LOC established.
Data generated by the limiting oxygen concentration test is predominantly used for either design of nitrogen inerting systems or to confirm a material is appropriate for processes with an established limited oxygen atmosphere.