Personal Protective Equipment - Eventsforce · 2019. 9. 1. · specified in prEN 16350 • Vertical...

Personal Protective Equipment

Dr Paul Holdstock Member of IEC/TC31 & TC 101/Joint Working Group 29

Convenor of CEN/CLC Joint Working Group on PPE Against Electrostatic Risks

holdstock technical services

Outline

• Basis of safety guidance • IEC/TS 60079-32-1

– Avoiding electrostatic risks from people – Footwear – Clothing – Gloves – Other PPE

11th December 2013 Electrostat-Ex 2013 - Personal Protective Equipment 2

Outline

• CEN/CLC Selection, Use, Care & Maintenance Document (SUCAM) – Risk assessment – Clothing – Footwear – Gloves – Other PPE



clothing is tribocharged (-)

(+) image charge on skin

(-) charge pushed to extremities, i.e. feet &

hands

Unearthed person

Typical body voltages

*Pirici et al, Journal of Electrostatics 62 (2004) pp. 167 - 183

Situation Body Voltage Reference

Working at a bench 6 kV NFPA 77

Vinyl envelopes for work instructions 7 kV NFPA 77

Walking across a vinyl floor 12 kV NFPA 77

Work chair padded with polyurethane foam 18 kV NFPA 77

Poly bag picked up from a bench 20 kV NFPA 77

Walking across a carpet 35 kV NFPA 77

Getting out of a car 20 kV Pirici *


Body voltage required to ignite typical IIA gas/vapour (e.g. methane) ~ 4 kV to 6 kV

Body voltage required to ignite sensitive IIC gas/vapour (e.g. hydrogen) ~ 1.5 kV

Earthed person


strong field towards body

weak field away from body

earthing removes unbalanced charge from body small or no

discharge

Loose clothing


weaker field towards body stronger field away from body concentrated by approaching conductor

hazardous brush discharge may occur

Risk of ignition is increased

Opening or removing clothing


strong field towards body

brush discharge may occur between clothing and body, which may cause ignition

Garment that has been removed


• Charge remains on garment after removal • Field is no longer attenuated by the body • Field is concentrated by approaching conductor • Large brush discharge may occur • Discharge may ignite explosive atmosphere

IEC/TS 60079-32-1: Structure

• Clause 11 – Static electricity on people – 11.1 General considerations – 11.2 Static dissipative floors – 11.3 Dissipative and conductive footwear – 11.4 Supplementary devices for earthing people – 11.5 Clothing – 11.6 Gloves – 11.7 Other items


IEC/TS 60079-32-1 : People

It is very important that people who may be exposed to flammable atmospheres having a MIE (minimum ignition energy) less than 10 mJ should be earthed to prevent them from becoming electrostatically charged


IEC/TS 60069-32-1 : Footwear • dissipative footwear : 100 kΩ ≤ R < 100 MΩ • has both an upper and a lower resistance requirement

… the upper level is low enough to prevent the build-up of electrostatic charge … and the lower level offers some protection in the event of accidental contact with mains electricity … suitable for general use

• conductive footwear : R < 100 kΩ • has a very low resistance and is worn, for example, by

people who have to handle sensitive explosives … should not be worn where there is any risk of accidental contact with mains electricity and it is not suitable for general use


IEC/TS 60079-32-1 : Footwear

• Resistances can be measured with commercially available footwear conductivity testers which measure the resistance between a hand-held metal bar via body and feet to a metal plate on which the person stands

• Test method is described in Annex G and IEC 60079-32-2 (enquiry draft at this date)


Ω

IEC/TS 60079-32-1 : Footwear


IEC 61340-4-3 (EN ISO 20344)

Mass of metal shot EN ISO 20344 : M = 4 kg IEC 61340-4-3 : M = 12.5 kg

IEC/TS 60079-32-1 c.f. EN ISO 20345

• IEC/TS 60079-32-1 (measured as worn) – dissipative footwear : 100 kΩ ≤ R < 100 MΩ – conductive footwear : R < 100 kΩ

• EN ISO 20345 (measured with metal shot) – antistatic footwear : 100 kΩ < R ≤ 1000 MΩ – conductive footwear : R ≤ 100 kΩ


IEC/TS 60079-32-1 : Clothing • … clothing should provide proper fitting and sizing (see

ISO 13688) and allow full body movement with all closures fastened according to manufacturer’s instructions

• Clothing should be as close fitting as is practical and should not be removed or unfastened in areas where there could be flammable atmospheres (e.g. Zone 0, Zone 1, Zone 20 and Zone 21)

• In situations where there is a combination of high charging activities and the presence of low MIE gases or vapours, the use of dissipative clothing may be required


Hazardous Zone

Probability of Charging 0.02 mJ ≤ MIE ≤ 0.2 mJ MIE > 0.2 mJ

Zone 0 High

REQUIRED

REQUIRED

Low Recommended

Zone 1 High

Low

Not Required Zone 2

High Recommended

Low Not Required

Zones 20, 21, 20 - Not Required


Expert advice should be obtained before selecting electrostatic dissipative protective clothing or equipment for use in hazardous zones with MIE less than 0.02 mJ.

IEC/TS 60079-32-1 : Clothing

EN 1149-5

• Protective clothing – Electrostatic properties – Part 5: Material performance and design requirements

• Two alternative test methods: – EN 1149-1: surface resistance for fabrics with

surface antistatic finishes (mainly nonwovens) and fabrics with surface conductive yarns; not suitable for testing fabrics with core conductive yarns

– EN 1149-3: shielding and half decay time for any type of fabric


EN 1149-5 / EN 1149-1 • R < 2.5 x 109 Ω • Conducting threads may be in a stripe or grid

pattern with spacing less than 10 mm in any one direction


Ω

EN 1149-5 / EN 1149-3


Key 1 Charge amplifier 2 Recording device 3 Field measuring probe 4 Guard ring 5 Specimen clamping ring 6 Test specimen 7 Support ring 8 Field electrode 9 Voltage generator

• Shielding factor S > 0.2, or • t50 < 4 s

IEC/TS 60079-32-1 : Gloves

• Gloves made from insulating materials could allow objects held in the hand to become and remain charged

• Gloves worn in Zone 0 and Zone 1 should, therefore, be made from dissipative or conductive materials


IEC/TS 60079-32-1 : Gloves

• Resistance is measured between a hand-held metal bar and a metal plate on which the person stands wearing conductive or antistatic footwear

• For general use resistance to earth via gloves should be less than 100 MΩ

• … and for critical applications (e.g. handling explosives) resistance to earth via gloves should be less than 100 kΩ.


Ω

IEC/TS 60079-32-1 : Other PPE • Protective helmets, breathing apparatus, visors etc.

made from plastics may become charged, but if they are used with care in accordance with manufacturer’s recommendations, they are unlikely to present an electrostatic ignition risk in Zone 1, Zone 2, Zone 20, Zone 21 or Zone 22 areas, provided there are no high charging activities

• … if there is a combination of high charging activities (e.g. wiping a visor) and low MIE gases or vapours present … the guidance given in Table 21 may also be interpreted for use with other items of personal protective equipment


IEC/TS 60079-32-1 : Other PPE

• In areas where the use of dissipative items is indicated … personal protective equipment should be made from dissipative or conductive materials (Table 1) … and earthed via the body of the wearer

• Any insulating materials used in the construction of personal protective equipment should be limited in area (Table 3)

• Annex G and IEC 60079-32-2 (enquiry draft at this date) describe methods that can be used to test other items of PPE


Enquiry draft of SUCAM document

• Carry out risk assessment – Identify hazardous areas, i.e. areas containing

explosive atmospheres – Classify areas by zone (Zones 0, 1, 2, 20, 21 & 22) – Classify explosive atmosphere (Explosion Groups I, IIA,

IIB, IIC, IIIA, IIIB and IIIC) – Determine MIE of explosive atmosphere – Consider possibility of oxygen enrichment – Size (area or width) of PPE – Mechanisms and probability of charging PPE – Environmental factors (temperature, humidity)


Selection Matrix for Static Dissipative PPE

Hazardous Zone

Probability of Charging

0.016 mJ ≤ MIE < 0.2 mJ MIE ≥ 0.2 mJ

Explosion Groups IIB, IIC

Explosion Groups IIA, IIB

Explosion Groups IIIA, IIIB, IIIC

Zone 0 High

REQUIRED

REQUIRED

Low Recommended

Zone 1 High

Low

Not Required Zone 2

High Recommended

Low Not Required

Zones 20, 21, 22

High Not Required

Low


Expert advice should be obtained in cases where MIE < 0.016 mJ (e.g. oxygen enrichment)

SUCAM : Clothing

• Requirements for static dissipative protective clothing are given in EN 1149-5

• Additional guidance on: – size limits for essential insulating materials (e.g.

reflective tapes, labels, etc.), referring to IEC/TS 60079-32-1 (Table 3)

– capacitance limits for isolated conductors (e.g. zip fasteners, D-rings, etc.), referring to IEC/TS 60079-32-1 (Table 2)


SUCAM : Footwear

• Resistance to earth limits for footwear flooring system are the same as IEC/TS 60079-32-1

• Reference is made to EN ISO 20345 for the requirements for footwear

• In-use testing prior to entering hazardous area is recommended


SUCAM : Gloves

• Materials used to make the palms, fingers and any areas that extend above the wrist of the wearer should meet the requirements for electrostatic dissipative protective gloves specified in prEN 16350

• Vertical resistance measured according to EN 1149-2 shall be less than 1.0 × 108 Ω

• Smaller electrodes as specified in IEC 61340-2-3 may be used if the sample material is otherwise too small


Vertical resistance

• EN 1149-2: Probe 1 centre electrode is 50.4 mm ∅, ring is 69.2 mm ∅ • IEC 61340-2-3: Probe 1 centre is 30.5 mm ∅, ring is 57 mm ∅


SUCAM : Gloves

• Resistance to earth limits for gloves as part of an earthing system are the same as IEC/TS 60079-32-1

• In-use testing prior to entering hazardous area is recommended


SUCAM : Other PPE

• Other PPE includes: – Head protection – Hearing protection – Eye and face protection – Respiratory protection – Hand and arm protection other than gloves – Protection against falls from a height – Personal floatation devices

• Respective product standards currently do not include requirements for electrostatic properties


SUCAM : Other PPE

• Where textiles and similar flexible materials are used, the requirements given in EN 1149-5 can be used, e.g. – hats, caps, hoods – outer fabric on elbow pads – fall arrest harnesses – textile components of floatation jackets


SUCAM : Other PPE

• Material used in the construction of PPE should be conductive or static dissipative and…

• should be capable of being earthed, either directly, or via the body of the wearer

• Materials should have a surface resistance of less than 2.5 GΩ measured according to EN 1149-1, or less than 5 GΩ measured according to IEC 60079-32-2


SUCAM : Other PPE

• The area or width of any essential insulating material should be less than the limits given in IEC/TS 60079-32-1 (Table 3)

• If the area or width of insulating material exceeds these limits, an evaluation should be made of the propensity for charging and generation of incendiary discharges either by – charge transfer measurement, or – ignition testing

• according to the procedures given in IEC 60079-32-2


SUCAM : Other PPE

The total system resistance between any metal or other conductive component (e.g. buckle, D-ring, fastener, bracket, etc.) and earth should be less than 10 GΩ, measured according to IEC 60079-32-2, unless the capacitance is less than the limits given in IEC/TS 60079-32-1 (Table 2)


Summary • IEC/TS 60079-32-1 gives guidance for personal

protective footwear, clothing and gloves, with information to help users select the correct PPE for different risks (hazard zones, probability of charging, etc. )

• CEN/CLC SUCAM document gives similar guidance but is more detailed in its guidance, particularly for other items of PPE

• Specific requirements for clothing, footwear and gloves are well defined

• Currently, only general requirements can be given for other items of PPE


Personal Protective EquipmentOutlineOutlineUnearthed personTypical body voltagesEarthed personLoose clothingOpening or removing clothingGarment that has been removedIEC/TS 60079-32-1: StructureIEC/TS 60079-32-1 : PeopleIEC/TS 60069-32-1 : FootwearIEC/TS 60079-32-1 : FootwearIEC/TS 60079-32-1 : FootwearIEC/TS 60079-32-1 c.f. EN ISO 20345IEC/TS 60079-32-1 : ClothingIEC/TS 60079-32-1 : ClothingEN 1149-5EN 1149-5 / EN 1149-1EN 1149-5 / EN 1149-3IEC/TS 60079-32-1 : GlovesIEC/TS 60079-32-1 : GlovesIEC/TS 60079-32-1 : Other PPEIEC/TS 60079-32-1 : Other PPEEnquiry draft of SUCAM documentSelection Matrix for Static Dissipative PPESUCAM : ClothingSUCAM : FootwearSUCAM : GlovesVertical resistanceSUCAM : GlovesSUCAM : Other PPESUCAM : Other PPESUCAM : Other PPESUCAM : Other PPESUCAM : Other PPESummary

Personal Protective Equipment - Eventsforce · 2019. 9. 1. · specified in prEN 16350 • Vertical...

Documents

Transcript of Personal Protective Equipment - Eventsforce · 2019. 9. 1. · specified in prEN 16350 • Vertical...