Measurement of minimum ignition energies of dust clouds in the <1mJ region

Explosibility of micron- and nano-size titanium powders

“…For three nano-titanium sizes (35 nm, 75 nm and 100 nm), the MIE was lower than 1 mJ. 36 An energy of 1 mJ is the lowest value generated with the MIKE 3 and is therefore the limitation of the equipment used by Wu et al 36 However, 3 µm titanium has been seen to ignite at 0.012 mJ by Randeberg et al 37 Consistent results using materials such as iron and titanium have been difficult to obtain using the Siwek 20-L chamber. Wu et al 38 performed tests with nano-aluminum, nanoiron, and nano-titanium and dispersed them according to procedures described in section 4.2.1.…”

“…Randeberg et al 37 demonstrated that 3 µm and 9 µm titanium can ignite at energies as low as 0.012 mJ and 0.36 mJ, respectively. The MIE of titanium is very low for small micron sized particles.…”

A Review of the Fire and Explosion Hazards of Particulates

“…Whether pyrophoricity occurs in practice depends on a heat balance involving factors like exothermicity of the oxidation reaction, particle size, thickness of oxide layer, and boiling points of metal and oxide relative to adiabatic flame temperature 75,76) . The pyrophoric nature of fine powders of reactive metal, especially those in the nano range, complicates testing procedures to determine explosion indexes, requiring modification of standard dust explosion testing equipment and procedures for explosion severity 77) and explosion sensitivity 78) . Experimental measurements, complemented with theoretical studies, suggest some very interesting particle combustion and explosion phenomena unique to sub-micron/ nano-sized particles.…”

MIKE 3 versus HARTMANN apparatus: Comparison of measured minimum ignition energy (MIE)

“…This is due to the difficulty to quantify and reproduce experimentally real-world spark characteristics and especially sparks duration and synchronisation between dust dispersion and sparkover [6][7][8][9][10] (see discussion in Section 3.2). However, it is not possible to accurately qualify the ignition sensitivity of a sample according to the test result.…”

“…Randeberg and Eckhoff [10] pointed that MIE tests by using independent dust dispersion and spark triggering is not really representative of electrostatic discharges that actually occur inside a dust cloud in industrial situations, because of the difficulty to synchronise sparkover and optimal concentration.…”