Chemical Tankers / Day 1 / Day 1 Topic 6 Static Electricity

Chemical Training

Static Electricity

Static Electricity

What is Static Electricity?

What are the Dangers associated with Static Electricity?

Discuss

6.1 General information about static electricity

Static electricity presents fire and explosion hazards during the handling of petroleum and during other tanker operations such as tank cleaning, ullaging and sampling procedures.

The primary concern related to static electricity is the possibility of generating an incendive spark within a flammable atmosphere.

6.1 General information about static electricity

Static electricity is generated by friction that occurs between different materials during relative motion with each other.

Electrostatic charges can then accumulate in materials which are poor conductors of electricity or which are good conductors but are insulated.

If two such bodies with accumulated static electricity charges are brought close together and if the difference of potential is great enough, the accumulated charge will jump between them.

6.1 General information about static electricity

Certain operations can give rise of accumulations of electric charge that may be released suddenly in electrostatic discharges with sufficient energy to ignite a mixture of flammable hydrocarbon gas & air mixture.

6.1 General information about static electricity

There are three basic stages leading up to a potential electrostatic hazard:

oCharge separation oCharge accumulation

oElectrostatic discharge

6.1 General information about static electricity

Charge separation:

Whenever two dissimilar materials come into contact, charge separation occurs at the interface.

Above interface may be between:

two solids

a solid and a liquid

two immiscible liquids

6.1 General information about static electricity

Chemical Tankers specific sources of charge separation:

The flow of liquid petroleum through pipes and fine filters;

Settling of solid particles in liquids (rust particles);

Settling of droplets of one liquid through another (water in cargo);

Breaking up of liquid in free fall (start of loading);