Minimum Ignition Energy test for dust cloud

Purpose

The purpose of the Minimum Ignition Energy (MIE) test is to determine the minimum energy of an electric spark needed to initiate a dust explosion.

For dust handling purposes the MIE is mainly used to assess the hazards of ignition by electrostatic sparks or discharges.

Electrostatic sparks and discharges can be generated from many activities, including:

emptying containers or bags
walking on non-conductive flooring
the flow of dust through a pipeline
and many more

Knowing how easy it is to create electrostatic sparks and discharges, performing this test is essential to learn the sensitivity of your product against the sparks and discharges.

In combination with the Minimum Ignition Temperature of dust clouds (MITdc), the minimum ignition energy can also be used to assess the hazards of ignition by mechanical sparks generated by friction (in rotating equipment), grinding, or single-impact sparks.

The incendivity of mechanical sparks depends especially on the material combinations involved, forces acting on the contacting objects, and relative speed.

Method

Minimum Ignition Energy test for dust cloud (MIE)

Gexcon performs MIE testing in accordance with European standard EN ISO/ IEC 80079-20-2:2016 “Explosive atmospheres – Part 20-2″ Material Characteristics – Combustible dust test methods“.

We disperse dust samples of various sizes inside the 1.2-litre vertical tube of the Modified Hartmann apparatus or MIKE3 apparatus. Next, we try to ignite the resultant dust cloud with different spark energies. Tests can be performed with and without an inductance in the ignition circuit used. The inductance lengthens the duration of the spark. Energies generated by ignition circuits without inductance are representative of electrostatic sparks. The minimum ignition energies determined with an inductance in the ignition circuit are used to assess the possibility of ignition by the mechanical spark.

We are using the Modified Hartmann apparatus for the following energies: 2, 5, 10, 15, 20, 50, 100, 200, and 2000mJ (with inductance)

As for the MIKE3 apparatus, we are using the following spark energies: 1, 3, 10, 30, 100, 300, and 1000mJ (with or without inductance).

Benefit

Determination of the MIE helps you understand the ignition sensitivity of your product when it forms a dust cloud and especially to assess hazards due to electrostatic and mechanical sparks.