Why should we worry about static electricity? - Electrostatic ...

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Maize starch dust explosion Vaksdal, Norway, April 1982 Photographer: A.M.Fosse From R.K. Eckhoff (1991) Dust Explosions in the process industries © Electrostatic Solutions Ltd 2 February 2006 www.electrostatics.net 4 Fire when refuelling car In the USA Fortunately this is unlikely to happen in the UK! © Electrostatic Solutions Ltd 2 February 2006 www.electrostatics.net 5 Why do fires and explosions happen © Electrostatic Solutions Ltd 2 February 2006 www.electrostatics.net
Fire triangle for static electricity SPARK FIRE EXPLOSION FIRE EXPLOSION AIR FUEL © Electrostatic Solutions Ltd 2 February 2006 www.electrostatics.net 7 The flammable atmosphere • The fuel could be – Vapours –Dusts – Droplets of liquid (mist) – A mixture of vapours and other materials • The fuel is usually essential to operations • In some cases the atmosphere may be inerted e.g. with nitrogen or CO2 © Electrostatic Solutions Ltd 2 February 2006 www.electrostatics.net 8 Minimum Ignition Energy (MIE) • To ignite a flammable mixtures the ESD energy must exceed the material Minimum Ignition Energy (MIE) • Different flammable mixtures have different MIE • MIEs of gases and hydrocarbon vapours in air are often around 0.1- 0.3 mJ • Some vapour MIEs can be as low as 0.02 mJ – hydrogen-air – ethylene-air – oxygenated mixtures • Dust clouds can have MIE from < 1mJ upwards – MIE varies with particle sizes and other factors © Electrostatic Solutions Ltd 2 February 2006 www.electrostatics.net 9
Page 1: Electrostatic fire and explosion ha
Page 5 and 6: Why don’t t we always get static
Page 7 and 8: Contact charging in processes • C
Page 9 and 10: Assess use of insulators • Avoid

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