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

Abstract

In this study, MIE values measured with two different explosion tubes, HARTMANN and MIKE 3, are compared. Generally, MIKE 3 apparatus provides MIE results, which are equal or lower to those measured with the HARTMANN apparatus; this is particularly true for the energy ranges between 1 and 10 mJ and higher than 100 mJ.Differences observed can modify samples classification according to their sensitivity to electrostatic ignition sources. Nevertheless, ignition of a dust cloud by an electrostatic discharge is complex, and implies a different mechanism from that occurring during MIE tests. Thus, it seems difficult to synchronise dust dispersion and spark triggering to obtain optimal concentration in the spark area. Moreover, spark characteristics such as duration or energy feeding rate of spark cannot reproduce exactly industrial-world ones. On this point, it is not possible to conclude if characteristics of MIKE 3 electric circuit, e.g., resistance and inductance, are more relevant than HARTMANN circuit ones.

Determination of parameters used to prevent ignition of stored materials and to protect against explosions in food industries

“…The apparatus used was the MIKE 3 [26], based on a Hartmann Tube [27]. The energy (E) (J) was calculated from Eq.…”

Statistical method for the determination of the ignition energy of dust cloud-experimental validation

“…It can be noted that ranges of MIE with MIKE3 and Hartmann are very large. Moreover, the granulometry is not given in the work of Janes et al (2007).…”

“…It uses two kinds of triggering circuits: the high voltage relay (Annex A2 in EN 13821 standard) for low range MIE (1e3 mJ), and the electrode movement, using a two-electrode system (Annex A3 in EN 13821 standard). Janes, Chaineaux, Carson, and Le Lore (2007) compared the results obtained with two kinds of apparatus mentioned above and found that:…”

Combining product engineering and inherent safety to improve the powder impregnation process

“…The ignition energy is varied by changing the capacitance of the electrical circuit and ranges from 1 to 1000 mJ. Circuit inductance is kept constant at 1 mH during the entire course of the procedure: working with an inductance increases the spark duration and thus decreases the MIE of a given dust, which is consistent with a conservative approach (Janès et al, 2008). Tests have been performed according to IEC standard 1241-2-3 (IEC, 1994).…”

“…Indeed, MIE is one of the major safety parameters for dust explosion and could give a good estimation of the powder flammability in presence of electrostatic field (IEC, 1994;Carson, 2001;AFNOR, 2003). Janès et al (2008) propose a classification according to the dust sensitivity to electrostatic ignition sources (Table 3). It will be used to interpret our experimental results.…”