Static Electricity safety in Industrial installations

Static electricity is one of the main causes of industrial fires and explosions. Proper earthing, bonding and operational control helps to minimize the risk of static electricity in an industrial installation.  

Static Electricity safely in Industrial installations

The contact and separation of two dissimilar materials generates static electricity. When a static charge exceeds a certain level, spontaneous discharges and sparks may occur, capable of igniting the flammable mixture.

Here you will find the best safety measures for controlling the static electricity in industrial installations. But before proceeding further, we must understand the typical situations capable to generate static electricity.

 

Causes of static electricity in Industrial installations

👉 The flow of low conducive liquids through pipes or from an orifice into a tank

👉 Process of agitation or mixing

👉 Splash filling of liquids/high velocity flows

👉 Stirring of bottom water

👉 Running of flat belts (non-conducive)

👉 Pulverized materials passing through chutes or pneumatic conveyors

👉 low through filters, throttle valves etc.

👉 Two phase flows

👉 Loose floating objects

👉 Flow through lengthy pipelines and pipelines of lesser diameter

👉 Flow of steam, air or gas from restricted opening or a hose, when steam is wet, or the air or gas stream contains particulate matter

👉 Motion of all sorts that involve changes in relative positions of contacting surfaces usually of dissimilar substances, liquids or solids or both of which usually must be a poor conductor of electricity.

👉 Trouble shooting/handling of printed circuit boards without using an electrostatic wrist strap.

👉 Placement of synthetic materials on or near electronic equipment.

👉 Rapid movement of air near electronic equipment (including compressed air to blow of dust)

👉 Sliding along handrails with plastic coverings.

👉 Walking on dry floors.

 

Hazards of Static Electricity

👉 Fire and explosion are the primary hazards associated with static electricity. The spark generated by static electricity has sufficient ignition energy to ignite flammable or explosive vapors, gases or dust.

👉 It can also produce unexpected electrical shocks to humans, which can lead to other dangers like falling from height  (for example, sliding along plastic covered rails), etc.

👉 Static electricity can produce false readings in sensitive instruments.

👉 Static electricity can cause dust to deposit on unwanted places.

👉 Static electricity can cause clogging and agglomeration of powders, thus preventing free flow in hoppers, chutes and silos.

 

Sequence of combating Hazards of static electricity

👉 Prevent generation of static electricity i.e. prevent charge generation

👉 If prevention of charge generation is impossible - prevent charge from accumulating.

👉 If prevention of charge accumulation is not possible then prevent discharge of charges from one object to another by jumping. 

👉 Prevent accumulation of flammable atmosphere in area where there is chance of charge discharge i.e. ensure that no flammable gas mixture is available in such areas.

 

Static Electricity safely in Industrial installations

Here are the general precautions to prevent hazards of static electricity.

👉 Generation of static electricity can be prevented by;

👍 Increasing the conductivity of floors, footwear, etc.

👍 Increasing the conductivity of nonconductors by incorporating conductive additives, surface layers and films and humidifying the atmosphere.

👍 Increasing the conductivity of the atmosphere by ionization.

👍 Keeping all synthetic materials at least 4 inches away from electronic equipment.

👍 Using a spray labeled as 'non-static forming' while cleaning printed circuit boards.

👍 Wearing a static wrist strap that is grounded with the frame of the device, while trouble shooting/handling electronic equipment.

👍 Using static floor mats where necessary.

👍 Proper bonding of conveyor belt structures

👍 Proper earthing of truck tankers before starting loading of flammable chemicals.

👍 Ensuring the earthing and bonding of stationary conductive equipment.

👍 Reducing the pumping speeds, especially in following situations:

👥 at beginning a storage tank filling operation

👥 when transferring a light product into a storage tank containing a heavier product of low conductivity.

👥 when transferring any product containing free water or air, for instance during cleaning of the lines.

👥 when transferring a product containing any other second phase such as immiscible liquids

👥 when changing the grade of product during pumping.

👥 water washing of hydrocarbon service pipeline

Some operation may require specific precautions to prevent hazards of static electricity, which must be followed strictly.

 

Summary

Static electricity is a leading cause of industrial fires and explosions if not managed properly. The prevention of static charges by controlling operation is the top priority, followed by safe discharge to earth. Grounding and earthing are the best solution to control the risk of static electricity.