Can Electrostatic Discharge (ESD) from Non-Conductive Bags act as an Ignition Source?

Hope you are enjoying the posts and able to gain some insights from the blog.

Now for this week blog, I am touching on a more sensitive question, which people have asked me in almost all Electrostatic Hazard Seminars. "Can Non-Conductive Bag act as an ignition source?"

A non-conductive bag, being an insulator can act as a source of Brush Discharge which has approximate energy of up to 3-4 mJ associated with it. Depending on the type of flammable atmosphere, brush discharge from the non-conductive bag may/ may not act as an ignition source.

Based on the equivalent energy of brush discharges, it must be assumed that most potentially explosive gas/air mixtures, solvent vapor/air mixtures and hybrid mixtures (vapor/gas and dust with air) can be ignited by brush discharges.

Are there two types of Minimum Ignition Energy (MIE) for powders?

Here we go. The first blog; let’s begin the blogging and sharing together.

Yes, there are two types of MIE, where one type is carried out without inductance and the other is carried out with inductance.

Minimum Ignition Energy is the minimum energy that is required for ignition of fuel. In other words, the minimum energy an ignition source must provide to the fire triangle for the fuel to burn in presence of an oxidant.
The test to establish MIE is carried out in an apparatus called MIKE3 (refer image below). It is performed using ASTM E2019, “Standard Test Method for Minimum Ignition Energy of a Dust Cloud in Air” or EN13821 “Potentially explosive atmospheres — Explosion prevention and protection — Determination of minimum ignition energy of dust/air mixtures”

MIE (Without inductance) corresponds to the energy required by electrostatic discharge to ignite a dispersed cloud. The circuit of MIKE3 for this test is purely capacitative and the spark energy can be related straight to 1/2*C*V^2 based on the capacitance selected.

MIE (With inductance) simulates the longer duration discharges from electronic circuitry that can occur from machines or control equipment (essentially a spark from short in a wire or electronic equipment) or mechanical sparks, by adding an inductance in the existing circuit.

Now one thing to remember is that MIE (With Inductance) is more conservative as compared to MIE (Without inductance). 

Next question that comes is which one to choose?

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Do you feel trouble understanding Process Safety Concepts? Do you feel that there is no place where someone in Process Safety business is not giving you any information for free? Have you ever felt sitting in a process safety seminar that why the author is not explaining the basic, before going into the detailed concept? Well if that's the case, this is the perfect portal for us to discuss. No one is judging you here for your lack of knowledge or for asking what you considered as a "DUMB" question or a basic concept.

I am a Chemical Engineer by qualification and Process Safety & Risk Consultant by profession catering to various sectors primarily Pharmaceuticals, FMCG, Metal, Chemicals, Plastic & Polymer, Wood & Paper and Oil & Gas. I do perform training, seminars, and webinars with the help of my present employer on different process safety aspects such as Electrostatic Hazards and controls, Dust Explosion protection and prevention, Hazardous Area Classification, Quantitative Risk Assessment, SIL & LOPA, HAZOP, Process Safety Testing for Powders, etc.

I have started this blog to share some of the insights of Process Safety and also to provide solutions to various general queries that we receive on day to day basis. Will also like to share my personal experiences while working on site and some views related to incidents happening around the globe.

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