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Safe Solutions for Electrostatic Dissipative Protective Clothing
Safe Solutions for Electrostatic Dissipative Protective Clothing
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Content
1. BEKAERT in a nutshell
2. what is static electricity ?
3. how to solve ?
4. standards
5. different solutions
6. conclusions
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Based in Europe, headquarters in Belgium
Sales of € 3.2 billion in 120 countries
18 500 employees
Worldwide production platform
Bekaert in a nutshell
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Bekaert is technological leader
Advanced materialsand coatings
Core competences
Advanced metaltransformation
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From wire rod to advanced wire products
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From ultra fine fibers to advanced materials
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From traditionalcoatings toadvanced coatings
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Bekaert is market leader
� Fibers (Nr. 1)
� Film Coatings (Nr. 2)
� Premix gas burners�for condensing boilers (Nr. 1)
� Champagne cork (Nr. 1)
� Dramix® (Nr. 1)
� Coated wire (Nr. 1)
� Tire cord (Nr. 1)
Examples
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Stainless steel fibres and yarns used in:
�ESD (Electro-Static Discharge)
� Protective clothing
� Anti-static filtration
� Floor covering & upholstery
� Brushes
� Big Bags
� Electromagnetic Shielding (EMI)
� Heatable textiles
� Electrotherapy
� Intelligent textiles
ECT - Electro Conductive Textile Applications
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1. BEKAERT in a nutshell
2. what is static electricity ?
3. how to solve ?
4. standards
5. different solutions
6. conclusions
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What is static electricity ?
- To many people, static electricity is little more than the shock experienced when touching a metal doorknob after sliding across a car seat or walking a carpeted room.
- Is caused by rubbing of 2 different materials (TRIBO-Series)
- Some materials want to give away electrons and other materials want to receive materials = TRIBO-CHARGING
- ESD or Electro-Static Discharge is the transfer of charge from one object to another, which results in an electrical current.
• example : person walking over carpet can generate up to 30000 V
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Charge transfer by induction
- When a non charged earthed conductor is brought into the electric field of a charged object, the electrons rearrange and the charge leaks away to the ground = INDUCTION
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TRIBO-Series
Positive ++++++ Human hands
+++++ Glass
++++ Human hair
+++ Nylon
++ Wool
+ Paper
Neutral 0 Cotton
- Steel
-- Wood
--- Copper
---- Acetate, Rayonne
----- Polyester
------ Polyethyleen
------- Polypropyleen
-------- Vinyl (PVC)
Negative --------- Teflon ®
Example: PES with Fluor carbon coating will charge up quickly
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• Combing hair
Static electricity in our daily lives
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• Combing hair
• Stepping out of your car
Static electricity in our daily lives
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• Combing hair
• Stepping out of your car
• Opening a door
Static electricity in our daily lives
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• Combing hair
• Stepping out of your car
• Opening a door
• Taking out a sweater
Static electricity in our daily lives
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• Combing hair
• Stepping out of your car
• Opening a door
• Taking out a sweater
• Thunderstorm
Static electricity in our daily lives
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• Getting a dangerous electrical shock
Discomforts and risks
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• Getting a dangerous electric shock• Fire and/or fall-out of electric installations after lightning stroke
As a thunderstorm grows, electrical charges build up within the cloud. Oppositely charged particles gather at the ground below. The attraction between positive and negative charges quickly grows strong enough to overcome the air's resistance to electrical flow. Racing toward each other, they connect and complete the electrical circuit. Charge from the ground then surges upward at nearly one-third the speed of light and we see a bright flash of lightning .
Discomforts and risks
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• Getting a dangerous electric shock• Fire and/or fall-out of electric installations after lightning stroke• Explosion danger (gasses, fuel, dust, vapor)
Discomforts and risks
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• Getting a dangerous electric shock• Fire and/or fall-out of electric installations after lightning stroke• Explosion danger (gasses, fuel, dust, vapor)• Damage to micro-electronics (<100 V, 40-50% failures)
Discomforts and risks
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ESD garments for electronic assembly industry
Charged garments can damage micro-electronic components without touching (induction)
- All accumulated charge needs to be led away
- Seems need to be conductive
- Earthing of garment and person is required
This will avoid damage by induction charge
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Areas where ESD control is necessary
- Flammable and explosive Atmospheres - ATEX (EN1149)
• Petrochemical and Gas industry
• Chemical industry
• Fire Brigade
• Ammunition and fire work production
- EPA/Clean room environment (EN61340-5-1)
• Micro electronic industry
• Bio technological industry
• Hospital operating theatre (e.g. to protect vital electronic equipment)
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1. BEKAERT in a nutshell
2. what is static electricity ?
3. how to solve ?
4. standards
5. different solutions
6. conclusions
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How to solve?
1. Conductive Yarn : use conductive fibres or filaments to allow transport of electrostatic charge through the yarn
2. Conductive Fabric : use a grid of conductive yarns
3. Conductive garment : sew each part together with conductive sewing threads
4. Wear Conductive Socks and Shoes to make connection to earth
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How are conductive yarns made?
- Spun Yarns : an amount (1%-20%) of Bekinox® Stainless Steel Fibres can be blended during the spinning process with all kind of fibres: PES, PP, PA, Co, Wool, Nomex®, Kermel®…
• 1 – 2% : blended throughout the whole fabric
• 20 % : conductive yarns in grid
- Multifilament yarns (clean room) : PES or PA multifilament yarns twisted with a Bekinox® Stainless steel monofilament
- Result: fabric with a resistance of 105 – 106 Ohm
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- Natural resistance to TRIBO-charging
• e.g. Cotton is better then PES because it absorbs more water
- Charge accumulation should be avoided to avoid induction
- Immediate discharge in earthed condition
- Conductivity should remain even after frequent washings (laundry service, > 50 cycles)
ESD garments must fulfill following requirements
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1. Bekaert in a nutshell
2. what is static electricity ?
3. how to solve ?
4. standards
5. different solutions
6. conclusions
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Standards EN1149 & EN61340-5-1
- EN1149: standard for protective clothing used in flammable and explosive atmospheres
• EN1149-1: Test method for measurement of surface resistivity (for surface conductors only)
• EN1149-3: Test method for measurement of charge decay (suitable for core and surface conductors)
- EN61340-5-1: standard for garments used in the manufacturing and assembling process of the electronic industry (point-to-point and sleeve-to-sleeve)
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1. Bekaert in a nutshell
2. what is static electricity ?
3. how to solve ?
4. standards
5. Surface and core conductors
6. conclusions
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Surface and Core Conductors
Carbon core, PA outer layer
Carbon core, PA outer layer
Carbon core, PA outer layer
Carbon outer layer, PA core
Stainless steel
Construction
P140®
Negastat®
Belltron®
Resistat®
Bekinox®
Brand StandardProducerTypeFiber
EN1149-3BarnettCore Conductor
EN1149-3DuPontCore Conductor
EN1149-3KaneboConductor
EN1149-1, EN61340-5-1ShakespeareSurface Conductor
EN1149-1, EN1149-3, EN61340-5-1
BEKAERTSurface Conductor
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New method for Core Conductors : EN1149-3
- Due to their insulating outer layer, Core Conductors, e.g. Negastat®, Nomex P140®, cannot be measured according to EN1149-1
- EN1149-3 has been developed to measure both Surface and Core conductors
- Bekinox ® can be certified according to EN1149-1 and EN1149-3
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Earthing yes or no?
- Described in EN1149-5
- If people are insulated from earth, there is a serious risk, due to accumulated electrostatic charge, that sparks from the people themselves can ignite a flammable or explosive atmosphere
When not earthed, no matter what type of garment the worker is wearing, the human body can still produce ignitions
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Tests have proven that
- Garments with Bekinox fulfill all these conditions• Immediate discharge in earthed condition
• No rest charge
• Characteristics remain even after 200 industrial washings
- Garments with Core conductors e.g. Negastat (By Barnett)• The person can be earthed, but the garment not because of insulating outer layer
• Charge up easily, even in earthed conditions
• Discharge time can take several minutes
- Garments with carbon-suffused monofilaments e.g. Re sistat (By Shakespeare)• Have less good washing characteristics (only 1 µm carbon on PA6 core)
• Are a lot less conductive then metal fibres; more needs to be added to have the same result
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Example : Charging of a Core Conductor Fabric
In the next animation you will see:
1. The measuring instrument (oscilloscope)
2. The discharge of the garment (earthed electrode)
3. The charge of the garment (corona spray charger)
4. The discharge of garment (earthed electrode)
5. The measured value (oscilloscope)
• The tested garment is made with core conductor yarns and is in earthed condition
- Test were done by Dr. Ulrich von Pidoll, managing Director, Physikalish Technische Bundesanstalt (PTB) Braunschweig, Germany
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Long discharge time for core conductors
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Test Results Core Conductor Fabric
- Even in earthed conditions there is still a rest charge
- Reason: a rest charge remains on the fabric big enough to cause a serious discharge or charge induction
- The same test has been done with Bekinox® but without discharge
- Bekinox® passes the test successfully because no rest charge
Core conductors should not be used
in ESD protected environment (EPA)!
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1. BEKAERT in a nutshell
2. what is static electricity ?
3. how to solve ?
4. standards
5. Surface and core conductors
6. conclusions
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Conclusions
- People wearing electrostatic dissipative clothing, always need to be properly earthed to avoid discharge from human body
- With Bekinox® no rest charge, Core Conductors discharge slowly (rest charge present)
- Garments with Bekinox remain conductive after > 50 laundry cycles
- garments containing core conductors should be avoided in electronic assembly industry because of risk for induction charging
Result : Bekinox ® is The Safest Solution
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better together
www.bekaert.com www.swicofil.com/bekintex.html
