3. Contd….
Electricity :-
• The flow of Electrons through conducting material is
called as electricity
• The current flow from positive terminal to negative
terminal of battery when connected to DC supply.
4. 12/28/2023 4
Static Charge :- When a material or object holds a
net electrical charge, either positive or negative, it
is said to have a static charge.
Types of Static Electricity
1) Volumetric :-Charge Imbalances within the
body of a material
2) Surface :- Charges on very outer surface
of a material.
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ATOMIC STRUCTURE
• Substance
Molecules Atom
• The atom is
composed of
protons, neutrons
and electrons
– Protons have a
positive charge
– Electrons have a
negative charge
– Neutrons are
neutral
7. 12/28/2023 7
CLASSIFICATION OF MATERIAL
• Conductors:- a conductor is a material which
contains movable electric charges.
– When external energy supplied to the metal
movable electric charges continue to “bump”
each other and thus electric current flow through
the conductor.
8. 12/28/2023 8
CLASSIFICATION OF
MATERIAL
Contd…..
• Insulator :-
- Material those resists the flow of
electric current through it . Or
- They don’t have free charges, even if
external energy supplied to them.
e.g. Rubber, plastic.
9. 12/28/2023 9
HOW STATIC CHARGE GENERATE?
“separation of electric charges into equal and
opposite polarity by the contact and separation
of two substances having different physical and
chemical structure at the contacting surfaces”.
(IS 7689: 1974)
• These Substances may be Solid- liquid or solid-
solid or solid-liquid
(Condition is both must be properly insulated)
10. 12/28/2023 10
Contd…..
HOW STATIC CHARGE GENERATE?
“Generation of electric charge, usually occurs
whenever a liquid, flow through solid or
another liquid.” (OISD-110)
The degree of charge generation in the case of
oil products depend on
i) Nature of such liquids or solids
ii) Concentration of certain trace compounds
which are nearly always present in solution in
oil products.
iii) Rate of flow of liquid
v) Materials turbulence
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Factors Affecting for Static Charge
Generation
a)Type of Material :-
e.g. hard rubber, when rubbed against nylon, will
become negatively charged whilst when it is rubbed
against polythene will become positively charged.
b) Repetition:-
e.g. plastic web moving over a series of Teflon on rollers
will increase its surface charge after every roller.
12. 12/28/2023 12
Factors Affecting for Static Charge
Generation
c) Humidity:-
Dry Environment-higher the level of static
charge.
d) Change in Temperature :-
e.g. In case of injection moulding which is
apparently neutral when hot Subsequently be
found to have a large surface charge once
cool.
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Examples
A) General Examples :-
1) Rubbing of comb on hair and bringing it near the paper
dust- paper dust gets attracted towards comb
2) Removing Polyester Shirt from body and hanging on
Aluminum hanger-produce spark and noise
3) A person suddenly standup from the plastic chair .
4) A Television cover or screen gets deposited with static
charges.
15. 12/28/2023 15
Contd….
B) Examples from Factories:-
1) Static Charges develop when a fluid flows
through a pipeline or from an opening into a
tank or Splash filling .
2) Belt moves on non conductive Pulley
Examples
17. 12/28/2023 17
Examples
Contd….
4) Packing :-Static Charge attract dust and dirt , so
that labels does not stuck on product properly-
results in bad quality .
5) Plastic :- Injection molded parts attract contaminants
in air and causes shock to handling personnel due
to static charges- results in decrease in Efficiency .
6) Textiles:- Static charges cause threads to bind and
break in creels and wrappers- results in Machine
downtime.
7) Medical Device Manufacturing: static charges attract
contaminants towards small plastic parts prior to
packaging- Decreased quality.
19. 12/28/2023 19
Contd…
a) FIRE AND EXPLOSION
- Caused by discharging of accumulated static
charges on that object, that contains enough
energy to ignite flammable or explosive
vapours, gases or dust present in the vicinity.
Eg. Petroleum, Chemical, Explosive Industries
.
20. 12/28/2023 20
Contd…..
CHEMICAL Minimum Spark
Ignition Energy
(mj)
Maximum
Experimental
Safe Gap
(mm)
Methane 0.47 1.14
Ethane 0.285 0.91
Propane 0.305 0.92
Methonal 0.215
24. 12/28/2023 24
Effective means must be available for Static
Charge Generation.
Capable of accumulating sufficient no of
separate charges (Positive and Negative) on
PLANT, PRODUCT or OPERATOR and
maintain suitable Electric Potential
Difference .
spark must occur in ignitable mixture (But it
must have sufficient energy to ignite.)
Note :- If any one of above condition not satisfied then Fire Or
Explosion will not took place due to ESD.
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Control Measure to avoid
Hazardous Effects
A) Control Of Charge Generation
• Reduce unnecessary friction process / operation.
• (Ensure submerge filling)
Avoid free fall – for this fill the oil in tanks from
bottom
• Control flow velocity keep it up to less than 1meter /
sec (as per International safety guidelines for oil
tankers and terminals. ISGOTT) .
(Ensure streamline flow instead of turbulence flow)
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Control Measure to avoid Hazardous
Effects
Maximum flow velocity for non conductive hydrocarbons
(IS7689: 1974)
Pipe Diameter (mm) Maximum flow velocity (m/s)
10 8.0
25 4.9
50 3.5
100 2.5
200 1.8
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Contd…
B) Reduce Charge Accumulation
1) Do bonding (for conducting bodies)
Bonding is the process of connecting together two or
more conductive objects by means of a conducting wire
or strip to eliminate potential difference between these
objects
e.g., bonding across flanges of a metallic pipe.
Control Measure to avoid
Hazardous Effects
29. 12/28/2023 29
Contd…
2) Earthing:-
Bodies which has the potential to accumulate
the static charge must be grounded preferably
by bare conducting metal wires or strips
(Aluminum or Copper).
Control Measure to avoid
Hazardous Effects
30. 12/28/2023 30
3) In case of mobile apparatus like wheels, or roller:-
use conductive rubber.
4) Rotating Shaft :- it should be connected to the
earth by carbon brush or sliding metal contact. Or
use conductive grease.
5)Charge accumulation on person:- avoid wearing of
silk clothes and metal article.
Control Measure to avoid
Hazardous Effects
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Control Measure to avoid
Hazardous Effects
E) Increasing the Conductivity of floors ,
footwear.
e.g. PCB manufacturing Industry
Explosive Manufacturing Industries
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STATUTORY PROVISION
The Maharashtra Factories Rules, 1963:-
Sect. 70 (3) Protection Against lightning :-
Sect. 70 (4) Protection Against Ignition:-
(b) effective measures shall be adopted for prevention
of accumulation of static charges to a dangerous
extent.
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A)The Explosive Rules, 2008:-
Schedule-V, Part 4: Conditions for various license
set-v:-
During mixing and loading a positive grounding device
and semi-conductive hose shall be used to prevent
accumulation of static charges. Supervisor shall
evaluate all system to ensure that they will adequately
dissipate Static Electricity under potential field
conditions.
STATUTORY PROVISION
35. 12/28/2023 35
STATUTORY PROVISION
Contd….
The Explosive Rules, 2008:-
Schedule-VI :-
Part 1:- Safety provision for manufacturing explosives:-
Machines and equipments should be provided with
protection system for safe ESD.
Part- 2:- Safety provision for bulk mixing delivery (BMD)
vehicle.
while unloading from BMD vehicle into the blast holes,
hose must be of semiconductor type.
36. 12/28/2023 36
STATUTORY PROVISION
Contd….
B) Petroleum Rules 2002:-
Rule no 78:- Precaution against static charges
i) All petroleum lines should be continue and
earthed.
ii) While loading and unloading tanker
chassis and filling pipe must be bonded.
iii) The rate of fluid flow not more than
1meter/sec.
iv) One tanker should not be used for two
different class petroleum product.
38. 12/28/2023 38
1) Chemical Factory having MS cylindrical
Storage Vessel (for Petroleum product)
2) Storage Vessels :-
a) 24 KL - 2 nos
b) 30 KL – 1no.
3) Worker were unloading the petroleum
product from tanker lorry into the storage
vessel no 3 of 30KL capacity.
39. 12/28/2023 39
Contd…..
4) Action :-Connected rubber hose to the out let
valve of Lorry tanker and other end to the 30KL
horizontal tank valve.
5) While unloading there was leakage.
6) To stop the leakage worker started the lorry to it
forward or reverse.
7) Immediately there was sudden fire, workers tried
to extinguish it but till time it was converted into
fire ball.
40. 12/28/2023 40
Contd…..
Causes:-
1) Unloading oil from the road tanker to
the M.S. tanks without providing
proper bonding to the road tanker and
the storage tank.
2) Earthing was not done to avoid the
risk of static electricity.
42. 12/28/2023 42
Contd…..
For producing spark following conditions are
required
i) Voltage =350 V (at sea level, for shortest gap)
voltage =75000 V (in air for the 1inch gap)
ii) Energy stored in accumulated static charge
can be calculated as
Energy (E)= ½ Charge (Q)X Voltage (V)
Q= CV
Therefore,
E= ½ CV2
43. 12/28/2023 43
b) Lightning :-
-Results in burn or death of person
Because :-
i) Current capacity= 20-25 KAMP
ii) Energy = 1000-10000 MJ
iii) Temperature = more than 15000 C
44. 12/28/2023 44
Effect of Current on Human body
1 to 8 ma
(0.002-
0.010 J-)
Perceptible but not painful
8 to 15 ma
(0.25J)
Painful shock, individual can let go at will, as
muscular control is not lost
15 to 20 ma Painful shock, muscular control of adjacent
muscles lost, cannot let go.
20 to 50 ma Severe muscular contraction, breathing difficult.
50 to 100
ma (10J)
(Possible) Ventricular fibrillation, a heart condition
that results in death.
200 ma and
above
Certain) Severe burns, muscular contraction so
severe that chest muscles clamp down the heart
and stop it during the duration of shock.
45. 12/28/2023 45
C) OISD:-
OISD 110:-
Recommended practices on static
electricity charge Generation control
i) Spraying, splashing and misting:- avoid free
falling
ii) Agitation and mixing:- Should not carry out in the
partially filled tank.
iii) Flow Velocity :-
a) In Tank:- 4.5 m/sec.
b) In Pipe :-
iv) Gauging and sampling:- should be carried out.
when pumping operation has been stopped (after
5Min)
46. 12/28/2023 46
Contd….
OISD 108:-
Recommended practices on oil storage and
handling.
- Cleaning of tank with gas or oil should be avoided
- All storage tank must continuously connected to
earth or bonding should be done t avoid static
charge.
