13 Sep Static Electricity – It can be a shocker!

Static Electricity – It Can Be a Shocker!

Static electricity may seem harmless when it causes clothing to cling or produces a small shock after walking across carpet. In the workplace, however, static electricity can become a serious ignition hazard when flammable vapors, gases, combustible dusts, or other ignitable materials are present.

Guide for Discussion

How Static Electricity Develops

Static electricity is an electrical charge that accumulates on the surface of a material. Charges can develop when materials contact one another and then separate.

Static charges may be generated during:

• Movement of liquids through pipes, hoses, filters, or other equipment.
• Transfer of petroleum products and other flammable liquids.
• Filling, dispensing, pouring, or spraying operations.
• Movement or settling of particles through liquids.
• Movement of powders or combustible dusts.
• Separation of certain plastic or synthetic materials.
• Friction between belts, containers, clothing, ropes, or other materials.

If the accumulated charge suddenly discharges, it can produce a spark.

Why Static Electricity Is Dangerous

The shock from static electricity is often more startling than harmful to a person. The greater workplace concern is the possibility that the spark will ignite a flammable atmosphere.

A hazardous situation can develop when all three are present:

1. A material or process generates static electricity.
2. The electrical charge is allowed to accumulate.
3. Flammable vapors, gases, dusts, or other ignitable materials are present.

A static spark may contain enough energy to ignite certain flammable mixtures.

Flammable Liquid Transfer

Extra precautions may be necessary when transferring flammable liquids between conductive containers.

• Follow established procedures for dispensing and transferring flammable liquids.
• Use approved containers and dispensing equipment.
• Keep containers closed when not actively transferring material.
• Eliminate ignition sources from the area.
• Provide adequate ventilation when required.
• Use bonding and grounding when required for the material, containers, and operation.
• Inspect bonding and grounding equipment before use.
• Never assume that touching containers together provides an adequate bonding connection.

Bonding

Bonding electrically connects two conductive objects so they remain at approximately the same electrical potential.

When bonding is required:

• Attach the bonding connection before beginning the transfer.
• Connect to appropriate conductive surfaces.
• Maintain the connection throughout the transfer operation.
• Inspect cables and clamps for damage, corrosion, or poor connections.
• Remove the connection only after the transfer operation has been completed.

Bonding helps prevent a spark from occurring between conductive objects because of a difference in electrical potential.

Grounding

Grounding provides an electrical connection between a conductive object and ground, allowing accumulated static charge to dissipate.

• Use designated grounding points and approved equipment.
• Make sure connections are secure.
• Do not connect grounding equipment to painted, heavily corroded, or otherwise nonconductive surfaces unless specifically designed for that connection.
• Inspect grounding cables and clamps regularly.
• Follow equipment manufacturer and company procedures.

Bonding and grounding serve related but different purposes, and some operations may require both.

Control Static at the Source

Depending on the operation, static hazards may also be reduced by:

• Using equipment and materials designed for the application.
• Controlling transfer rates when required by established procedures.
• Avoiding unnecessary splashing or spraying of flammable liquids.
• Using conductive or static-dissipative equipment where appropriate.
• Maintaining required bonding and grounding connections.
• Using appropriate ventilation.
• Substituting materials or processes that generate less static when feasible.
• Following the SDS and manufacturer instructions for the materials being handled.

Never improvise bonding or grounding arrangements when handling flammable or combustible materials.

Dry Conditions

Static charges tend to accumulate more readily under dry conditions. Workers should therefore be especially alert to static hazards during periods of low humidity or in operations that naturally create dry environments.

Dry conditions do not create the only static hazard, however. Static electricity can occur whenever the appropriate materials and processes allow electrical charge to accumulate.

Before Starting Work

When working around flammable liquids, gases, vapors, or combustible dusts, ask:

• Can this operation generate static electricity?
• Are flammable or combustible materials present?
• Is bonding or grounding required?
• Are cables, clamps, and connections in good condition?
• Are containers and transfer equipment appropriate for the material?
• Are other ignition sources controlled?
• Is adequate ventilation provided?
• Have applicable SDS and company procedures been reviewed?

If you are unsure whether bonding, grounding, or other static-control measures are necessary, stop and ask your supervisor before proceeding.

Remember

A static spark that seems insignificant can become an ignition source in the presence of flammable vapors, gases, or combustible dusts. Recognize static-producing operations and use required bonding, grounding, ventilation, and other controls.