static electricity on oil tankers

OIL TANKER FAMILIARIZATION COURSE.

INTRODUCTION TOSTATIC ELECTRICITY AND IT’S SOURCES:

STATIC ELECTRICITY - DEFINITION

• Static electricity 

The build-up of electric charge on the surface of dissimilar objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge.

STATIC ELECTRICITY – How is it created?

• Materials are generally neutrally charged – equal number of electrons and protons.

• However, some materials when rubbed/moved, have a tendency to loose electrons quite easily.

• They then develop a positive charge and the surface they are rubbed on develop a negative charge.

• When any positive / negatively charged material is brought close to a ‘neutral’ or ‘ opposite’ charged surface, there can be a discharge ( due to the difference in potential between both surfaces) causing the phenomenon of static electricity.

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SOURCES OF STATIC ELECTRICITY ON SHIP.

To be discussed during this lecture:

• OIL MOVING THROUGH PIPELINES

• STATIC GENERATION DUE TO SPLASHING AND SPRAYING

OIL MOVING THROUGH PIPELINES.

1. Oil moving through a pipeline : frictional resistance near the pipe wall and smooth movement near the central axis of pipe.

2. This disturbed movement, along with impurities in oil causes separation of molecules.

Stationary Oil droplet – no charge.

OIL MOVING THROUGH PIPELINES.

1. The molecules then break up into charged particles, as displayed in the diag. above. Electrons break free and accumulate as negative charge on the sides of the pipe and positively charged oil particles start accumulating within the tank.

2. Once, the flow increases, build up of electron within the pipe accumulates.

3. Eventually the excessive negative charge built up within the pipeline can be scooped an delivered into the tank where positively charged oil already awaits- this can cause a static electricity discharge.

+++++++VE - - - - - - -VE Positively charged oil moving through pipeline: -ve ions left behind in pipe.

WATCH THE CHARGES SEPERATE.

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+++++++VE- - - - - - -VE

STATIC DUE TO SPLASHING/ SPRAYING

aa) Uncharged condition bb) Commencement of charge separation cc) Charged oil droplet

Tank

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Uncharged oil

droplet

Charge developing

Charged oil droplet

Tank

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Tank

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STATIC DUE TO SPLASHING/ SPRAYING

aa) Uncharged condition bb) Commencement of charge separation cc) Charged oil droplet

Tank

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khea

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Uncharged oil

droplet

Charge developing

Charged oil droplet

Tank

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khea

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Tank

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ANY QUESTIONS ?

THANK YOU FOR BEING AN ATTENTIVE AUDIENCE.