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Electrostatics in the Factory by the Numbers

Charge, discharges, ignition, earthing, powder coating, ionisers, ESD control and electrostatic precipitators on the shop floor

How static charge builds up, discharges and ignites, and how factories control it and put it to work in powder coating, ionisers, ESD-safe assembly and fume precipitators, with numbers.

10 chapters · About 100 minutes · Free to read · Intermediate engineering and production

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BIZOMAT LibraryMANUFACTURINGElectrostaticsin the Factoryby the NumbersBIZOMAT ORIGINAL BOOK10 CHAPTERS

About this book

Static electricity is the oldest electrical phenomenon people know and one of the least understood on a factory floor. It makes film cling and labels misfeed, attracts dust to freshly painted parts, shocks operators at a doorway, destroys electronic components that look undamaged, and, in the wrong place, ignites a flammable vapour or a dust cloud. The same physics, harnessed deliberately, charges powder coating so that it wraps around a part, neutralises charged film with a cloud of ions, and pulls welding fume out of the air onto metal plates.

This book explains static electricity as engineering. It starts with charge, field, voltage and stored energy, then how materials charge and how long the charge lasts, how gases break down into sparks and corona, and when a discharge can ignite something. It then covers earthing and bonding, electrostatic powder coating, ionisers, the control of electrostatic discharge (ESD) in electronics assembly, electrostatic precipitators, and running a static control programme.

It is for manufacturing, process, safety, quality and maintenance engineers, supervisors and technicians. It assumes engineering or trade training and comfort with voltage, current and simple algebra; the physics is explained as it is used. Each chapter works the running case with real numbers, includes one plausible mistake and how it was found, links the BIZOMAT tools that do the chapter’s calculations, and ends with an exercise and its worked answer.

The running case

Every chapter follows one factory. This is an illustration. A maker of steel electrical enclosures and control cabinets in Dandenong South, Victoria, cuts, folds and welds sheet steel, powder coats the enclosures, and assembles electronic control boards into some of them. Static matters in four places:

  • Powder line PL-2: a conveyorised powder coating line with two automatic corona guns and a manual touch-up gun, a booth with cartridge filter recovery, and a curing oven at 200 °C. Enclosures hang from steel hangers on an earthed overhead conveyor.
  • Assembly area: an ESD-protected area where technicians assemble and test control boards, and clean them with isopropyl alcohol.
  • Window line: polycarbonate viewing windows arrive with a protective film that is peeled off before fitting.
  • Welding bay: four welding stations extracted to a two-stage electrostatic precipitator that returns cleaned air to the building.

Charges, voltages, energies, airflows, prices and failure records are the factory’s working figures or are calculated from stated assumptions. They do not describe BIZOMAT work or any real business, equipment maker or supplier. Prices are in Australian dollars excluding GST, because a GST-registered business claims the GST back on its costs.

How to use the book

Chapters 1 to 4 explain charge, discharges and ignition; Chapters 5 to 9 earthing, powder coating, ionisers, ESD control and precipitators; Chapter 10 brings them together into a programme. Read Chapters 1 and 3 first; the others stand on their own once the case is familiar.

Each chapter links the BIZOMAT calculators it uses. The tools do the arithmetic; the chapter explains what the inputs mean and where they come from. Every result in the text was checked by calculation, and the numbers in figures match the text.

Limits and responsibility

This book is educational. Electrostatic ignition of flammable atmospheres is a serious hazard. Hazardous area classification, the selection of equipment for hazardous areas and the control of ignition sources must follow work health and safety law, the applicable Australian standards and the guidance of competent people, and powder coating booths and their electrical equipment must meet the standards that apply to them. High-voltage equipment such as powder guns and precipitators must be installed and maintained to the maker’s instructions by qualified people. Standards are named by number and scope only. Ignition energies, resistances and other values in the case are illustrations; use the material supplier’s test data, the equipment maker’s documents and your own measurements for real work.

Who this book is for

Manufacturing, process, safety, quality and maintenance engineers, supervisors and technicians who run powder coating lines, handle powders or solvents, assemble electronics or operate fume collectors, and want to understand and control static electricity.

What you will learn

  • Explain how objects become charged, how long the charge lasts, and how much energy a charged person, part or container can release in a spark.
  • Recognise the different kinds of electrostatic discharge, from corona to sparks, and judge which can ignite a vapour or dust.
  • Earth and bond conductive items, control humidity and use ionisers to keep charge below harmful levels, and check that the controls work.
  • Set up electrostatic powder coating for good transfer efficiency and coverage, and find the cause of poor film build and back-ionisation.
  • Run an ESD-protected assembly area and size and maintain a two-stage electrostatic precipitator for welding fume.

Inside this book

Chapters

  1. 01Charge, voltage and stored energyWhat static charge is, how charge, capacitance and voltage relate for people, parts and containers, how much energy a spark can release, and how to measure static voltages.
  2. 02How things charge and how long the charge lastsHow contact, induction and flow charge materials, how fast charge leaks from conductors, liquids and plastics, and how humidity changes surface leakage, with a winter humidity check.
  3. 03Sparks, brushes and coronaHow air breaks down, why points and edges make corona at low voltages, and how corona, brush, spark, propagating brush and cone discharges differ in where they occur and their energy.
  4. 04When a discharge can igniteWhat an electrostatic discharge needs to ignite a vapour or dust: a flammable mixture, enough energy compared with the minimum ignition energy, and the discharge in the right place.
  5. 05Earthing and bondingWhy earthing conductors and people is the most effective static control, why a megohm still drains static, how to earth parts, containers and people, and how to check the earth is there.
  6. 06Electrostatic powder coatingHow a corona gun charges powder, why charged powder wraps round an earthed part, what causes back-ionisation and thin inside corners, and how transfer efficiency drives powder cost.
  7. 07Ionisers for insulating surfacesHow ionisers neutralise charge on plastics and films, how passive, AC, pulsed DC and air-assisted types differ, why their range is short, and how decay time and balance are tested.
  8. 08ESD control in electronics assemblyWhy components fail from discharges too small to feel, how the human body and charged device models describe them, and how an ESD-protected area earths people, benches and parts.
  9. 09Electrostatic precipitators for fumeHow a two-stage electrostatic precipitator charges and collects welding fume, how migration velocity and the Deutsch equation set efficiency by particle size, and why cleaning matters.
  10. 10Running a static control programmeHow to bring earthing, humidity, ionisers, ESD control and precipitator care into one programme with checks, records, training and audits, and how to judge its business case.

Apply This in Practice

Use these BIZOMAT tools to try the method from this reading with your own numbers.

References and source notes

The manuscript and worked examples are original BIZOMAT writing. References inform particular concepts; their authors do not endorse this book. Web references were consulted on 2 November 2026.

  • P. M. Bellan, Cambridge University Press. Fundamentals of Plasma Physics (2006). Copyright work, used only as a map of ideas: charge shielding, quasi-neutrality, collisions between charged and neutral particles and the motion of charged particles in electric fields, which underlie gas discharges, corona and ion drift. The copy consulted was a 2004 manuscript of the book. No text, equations as set out there, figures or problems are reproduced, and all cases and calculations are BIZOMAT originals.
  • J. A. Cross, Adam Hilger. Electrostatics: Principles, Problems and Applications (1987). Background for charging mechanisms, charge relaxation, gas discharges, electrostatic hazards and industrial applications in Chapters 1 to 5.
  • M. Glor, Research Studies Press. Electrostatic Hazards in Powder Handling (1988). Background for the types of electrostatic discharge and their incendivity in powder handling in Chapters 3 and 4.
  • H. J. White, Addison-Wesley. Industrial Electrostatic Precipitation (1963). Background for corona charging, particle migration and precipitator efficiency in Chapter 9.
  • M. Pauthenier and M. Moreau-Hanot, Journal de Physique et le Radium 3, 590–613. La charge des particules sphériques dans un champ ionisé (1932). Named in Chapters 6 and 9 for the saturation charge of a spherical particle charged in an ionised field.
  • W. Deutsch, Annalen der Physik 68, 335–344. Bewegung und Ladung der Elektrizitätsträger im Zylinderkondensator (1922). Named in Chapter 9 for the exponential relation between precipitator collection efficiency, migration velocity, collecting area and gas flow.

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