MINIMUN IGNITION TEMPERATURE (CLOUD)
[EN 50281; ASTM E 1491]
The minimum ignition temperature (MITcloud) of a dust cloud is the lowest temperature at which a surface in contact with an explosive mixture of combustible dust and air can ignited the mixture.
For the determination of the minimum ignition temperature of a dust cloud according to Godbert-Greenwald (GG-oven) the powder is blown through a hot glass tube mounted vertically in a heating chamber.
Starting at 675°C the test is repeated with fresh samples by lowering the surface temperature in intervals of 20°C (below 300 °C intervals of 10°C) until no ignition (bang, flames) is observed.
In addition, the amount of powder injected into the tube and the blowing pressure is varied, because the flammability depends on the dust concentration and the residence time in the tube.
The minimum ignition temperature of a dust cloud is the lowest temperature at which an ignition can be observed.
The method according to Godbert-Greenwald (EN 50281) results in minimum ignition temperature of a dust cloud values which are on the average 50 °C higher than minimum ignition temperature of a dust cloud values determined according to BAM-oven (VDI-Guideline-2263, Part 1).