competence for safety dust groups · temperature (cloud) and glow temperature (layer) of the...

Competence for Safety There is a potential risk of explosion in industrial facilities wherever combustible dust is present, whether as a result of production or as a by-product. Deposited combustible dust has a high potential for explosion. It can be deposited everywhere in the equipment room and, in the case of a primary explosion, it is dispersed and can lead to a chain reaction causing numerous successive explosions. To prevent this danger to employees, the facility and the environment, it must be ensured that electrical equipment in these areas does not have any ignition sources. ATEX Directives 94/9/EC are applicable in this area as national regulations have been replaced by uniform EC rules.

This also includes a change to the definition for dust Ex zones: instead of the previous zones 10 and 11, dust EX zones 20, 21 and 22 have been defined similarly to the gas Ex zones 0, 1 and 2. Attached you will find Directive 1999/92/EC, Annex I.

Work areas are mostly classified as zone 21 or zone 22. Zone 20 is mostly limited to the interior of technical assemblies like silos or hoppers.

Occurrence of Potentially Explosive Dust Mixtures − The chemical industry − The pharmaceutical industry (active ingredients and auxiliary materials) − Power-generating companies or power plants (coal dust) − Wood-working industry operations (wood dust in filters

and silos) − Metal-working industry operations (swarf in traps) − Food and feed industries (dust from grains and sugar in

filters) − Industries that use plastic granulates

Dust Groups Dust is divided into two groups:

This difference is important when selecting equipment for zone 22 (explosive atmosphere not likely to occur or for a short period only and not during normal operation): Work equipment category 2D must be specified for conductive dust and also be certified for it. Work equipment category 3D must be specified for non-conductive dust.

For more information about the ATEX equipment category 3, see our “ATEX Category 3 Zones 2 and 22 info” flyer: Please request a copy.

Ignition Sources Ignition sources for a dust explosion can include: Static electricity, hot surfaces, mechanically-triggered sparks and interior ignition sources in an enclosure (housing) in which dust has penetrated. These ignition sources would cause an explosion if they ex-ceeded the ignition temperature of the dust during heating.

Non-conductive dust from natural products and chemical products

Conductive dust metal dust

Implementation of Protection Types For this reason, types of protection are designed for the following: − To prevent dust from penetrating (e.g. using pressurized

apparatus, protection by an enclosure or encapsulation) − To limit the electrical power and voltage of equipment in

intrinsically safe electrical circuits to a low level which will not cause sparks or a thermal effect that could ignite explosive atmospheres.

This is the “intrinsic safety” type of protection (modern type of protection also for gas EX protection). The major advantage of this type of protection is that the low energy of the intrinsically safe electrical circuits cannot cause ignition even when there are short circuits or sparks/arcs during fault conditions. For this reason, the cables of intrinsically safe equipment, for example, do not need to be installed in protective conduits. Usually, Sartorius weighing equipment for zone 21 features the "intrinsically safe" type of protection. An example of “protection by enclosure” is the EX recharge-able battery for Sartorius mobile weighing equipment.

Selecting the Proper Equipment The following considerations have to be taken into account when selecting the proper equipment for use in hazardous areas with potentially explosive dust atmospheres: 1. Determination of explosion parameters − Ignition temperature (method: dust as layered deposits, 5 mm thick) − Glow temperature (method: as dust cloud)

− Conductivity 2. Determination of the zone in which the equipment

should be used. This defines the required equipment category:

3. Comparison of the calculated ignition temperature of the dust with the max. permitted surface temperature of the equipment

A safety factor is calculated using the highest ignition temperature (cloud) and glow temperature (layer) of the respective dust: Values for specific dust can be taken from tabular values or they can be determined in the laboratory upon request. Tmax ign = Ignition temperature – 75K e.g. PVC: T Ign = 380°C-75= 305°C Tmax glow= Glow temperature*2/3 e.g. PVC: T Glow= 530°C*2/3= 353°C and the smaller value is compared as Tmax e.g. for PVC Tmax=305°C with the max. surface temperature of the equipment specified in the approval: e.g. Combics Ex weighing indicator: II 2G 1D EEx ib IIC T4 T135°C IP6* This means that this weighing indicator can be used for the PVC dust environment because the inequality Tmax dust (PVC= 305°C) > Tmax scale (surface indicator= 135°C) is fulfilled In this example: the PVC dust is only ignited by a high temperature of 305°C and the equipment can reach only a max. surface temperature of 135°C.

The general assertion – derived from the approval – is valid for this indicator: It can be used for explosive dust in zones 20, 21 and 22, for conductive or non-conductive dust with an ignition temperature of Tmax >135°C.

The following pages contain an overview of Sartorius products for zones 21 and 22 as well as combination examples for complete weighing solutions.

Conductive Non-conductive

Zone 20 1D 1D

Zone 21 2D (also 1D) 2D (also 1D)

Zone 22 2D (also 1D) 3D (also 2D, 1D)

For more information about the Sartorius product range available for potentially explosive atmospheres, see our “Sartorius Ex products overview” flyer. Please request a copy.

Sartorius AG Weender Landstrasse 94-108 37075 Goettingen, Germany www.sartorius.com

I would like to have a sales consultant phone me. Please send me your written information on the following:

A brief overview of Sartorius EX weighing equipment

Explosion protection document EX consultation services about our

products and those of other manufacturers compatible with ours ATEX category 3 (Zones 2 and 22) Risk assessment for non-electrical

equipment

FAX REPLY +49 (0)551.308.3495

Name __________________________________ Company __________________________________ Street Address __________________________________ City | Country | ZIP _________________________________ Phone __________________________________ Fax __________________________________ E-Mail __________________________________

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Weighing equipment for use in zone 21 (dusts)

Zone 21 (acc. to CENELEC, IEC)Division of hazardous areas according to the Directive 1999/92/EC, ATEX 137:

A place in which an explosive atmosphere in the form of a cloud of combustibledust in air is likely to occur in normaloperation occasionally.

This zone requires equipment group 2D(1D is also possible).

Combics series: CIXS3 indicator– With built-in A/D converter for analog plat-

forms for load cells up to 32 t; optional interface for digital platform

– Type of ignition protection: intrinsicallysafe, ATEX: II 2G 1D EEx ib IIC T4 T1 35°C

– Stainless steel housing with cable glands– 2 interface ports (1 RS-232C|RS-422|

RS-485 configurable by software) standard– 2 application kits for automatic single-

component filling up to a target weight– Can be networked with up to 8 client

devices

Combics series: CAPXS platforms– Weighing capacity from 0.1 g to 3 t,

also factory-verified for legal metrology– Type of ignition protection:

intrinsically safe, ATEX:II 2 GD EEx ib IIC T4..T6 T135°…155°C

– 11 different sizes– Low-profile, stainless steel design– Other materials optional for the load plate,

underframe, and lift-deck system– Can be used with Combics CIXS3 indicator

also in zone 20

Economy EC1XS stainless steel series – Weighing capacity from 0.1 g to 3 t– Type of ignition protection: intrinsically

safe, ATEX: II 2 GD EEx ib IIB T4 T155°C– Housing, display unit and platforms made

of stainless steel– RS-232C data interface standard

(optional RS-422 data interface)

PR62..|6 load cells– Wide capacity range up to 300 t– Type of ignition protection:

intrinsically safe, ATEX: II 1G (also 2G depending on the type) 1D EEx ib IIC T4 T85°C IP65

– Completely hermetically encapsulated, IP68– Various designs, mounting kits and

accessories:– Tension and bending beam load cells made

of special high-strength steel or stainlesssteel for platform, hybrid, tank and hopperscales and suspended vessels

– Compression load cells made of highlycorrosion-resistant stainless steel for precision weighing in tank, vessel and siloscales

– PanCake® level cells, ultra-low profiledesign (25|35 mm), for level-by-weightmeasurements of liquids and bulk solids

– Specialty load cells for trucks and freightcars

IFXS flat-bed scales– Weighing capacity from 0.1 g to 3 t, also

factory-verified for legal metrology(1 + 3000e|2 + 3000e; class l)

– Type of ignition protection: intrinsicallysafe, ATEX: II 2G 1D EEx ib IIC T4 T135°C

– High-grade material and outstanding work-manship – design ideal for use in the phar-maceutical industry

– Easy to clean thanks to load plate liftingmechanism

– Exceptionally low-profile design for especially easy loading

– High protection rating: IP68

IUXS pallet scales– Weighing capacity from 0.1 g to

1.5 t, also factory-verified for legalmetrology (1 + 3000e|2 + 3000e; class l)

– Type of ignition protection: intrinsically safe, ATEX:II 2G 1D EEx ib IIC T4 T135°C


Factory series:IS-X digital precision platforms– Weighing capacity from 0.001 g

to 300 kg, also factory-verified forlegal metrology

– Type of ignition protection: intrinsically safe, ATEX:II 2 G EEx ib IIC T4; from 16 kg and up: II2G 1D EEx ib IIC T4 T135°C

– With monolithic weigh cell (metrolog-ical advantages; built-in, motorizedcalibration weight, advantageous foruse in quality systems)

– RS-232C data interface standard(other optional data interfaces can beinstalled)

– For use as a digital, explosion-protect-ed “weighing sensor” connected toPLCs, or a max. of 2 platforms can beconnected to the Combics indicator(in a hazardous area) or to a series X5controller (in the non-hazardous areaand connected via converter|barrier)

– Can be networked with up to 8 clientdevices

Zone

21

Expl

osiv

e Du

sts

Cate

gory

II 2

D

Zone 21

12

Configurations with IS-X precision platforms in zone 21

Hazardous area Non-hazardous area

RS-485|RS-232C “ib”

PLC or PCIS-XUp to 8 platform workstations can be networked!

PLC or PCIS-X

ib

Interface converter or Zener barrier


Configurations with platforms in zone 21


Combics EX platform, CAPXS…

IFXS4 flat-bed scale

IUXS4 pallet scale

PLC or PC

Alternative configuration versions


Combics EXindicator

IS-X precision platform

EX load cells Combics EX series –analog platforms

Combics EX series indicator IFX flat-bed scale IUX pallet scale

13

Zone 21

Configurations with load cells in zone 21

Hazardous area

PLC or PC

PLC or PC

Load cells, e.g., PR62…

Combics EX platform or IS-X precision platforms

Non-hazardous area

Intrinsically safe interface

X5.. controller

Combics EXindicator


Load cells, PR62…


EX transmitter

19

Weighing equipment for use in zone 22 (dusts)

Zone 22 (acc. to CENELEC, IEC)Division of hazardous areas according to theDirective 1999/92/EC, ATEX 137:

A place in which an explosive atmosphere inthe form of a cloud of combustibledust in air is not likely to occur in normaloperation but, if it does occur, willpersist for a short period only.

This zone requires equipment group 3D(1D and 2D are also possible).

Combics series: CIS indicator + Option Y2– Can be used with Option Y2 in zones 2

and 22– With built-in A/D converter for analog

platforms for load cells up to 32 t – Type of ignition protection: “restricted

breathing enclosure,” ATEX: II 3GD EEx nR II T6 T80°C

– Stainless steel housing with cable glands– 3 data interfaces standard– Can be networked with up to 8 client devices

Combics series:CAPx platforms + Option Y2– Weighing capacity from 0.1 g to 3 t, also

factory-verified for legal metrology– Type of ignition protection: “non-sparking,”

ATEX: II 3 GD EEx nA II T6 T80°C– Low-profile, stainless steel design– Other materials optional for the load plate,

underframe and lift-deck system

Combics series:CW.S. complete scale + Option Y2– Weighing capacity from 0.1 g to 3 t, also

factory-verified for legal metrology– Type of ignition protection: “non-sparking,

restricted breathing enclosure,” ATEX: II 3 GD EEx nAR II T6 T80°C

– 4 display unit versions featuring differentlevels of applications

– Stainless steel material, 11 different sizes– Customized equipment and features

(interfaces, materials…) optionally available

IFS and IFP flat-bed scales with Option Y2– Weighing capacity from 0.1 g to 3 t, also

factory-verified for legal metrology (1 +3000e|2 + 3000e ; class l)

– IFS material: stainless steel; IFP material:painted steel; other materials optional

– Type of ignition protection: “non-sparking,”ATEX: II 3GD EEx nA II T6 T80°C

– High-grade material and outstandingworkmanship – design ideal for use in the pharmaceutical industry

– Easy to clean thanks to load plate liftingmechanism

– Exceptionally low-profile design forespecially easy loading


IUS and IUG pallet scales with Option Y2– Weighing capacity from 0.1 g to 1.5 t, also

factory-verified for legal metrology (1 + 3000e|2 + 3000e ; class l)

– IUS material: stainless steel; IUG material: galvanized steel

– Type of ignition protection: “non-sparking,”ATEX: II 3GD EEx nA II T6 T80°C


Factory series:IS digital precision platforms – Weighing capacity from 0.1 g to 300 kg,

also factory-verified for legal metrology– Type of ignition protection (150, 300 kg):

“restricted breathing enclosure,” ATEX: II 3 GD EEx nR II T6 T80°C

– Type of ignition protection (16…64 kg):“non-sparking,” ATEX: II 3 GD EEx nA II T4 T80°C IP65 (withoutbuilt-in motorized calibration weight)

– RS-232C data interface standard (otheroptional data interfaces can be installed)

– For use as a digital, explosion-protected“weighing sensor” connected to PLCs, or amax. of 2 platforms can be connected tothe Combics indicator (in a hazardous area)or to a series X5 controller (in the non-hazardous area)

– Can be networked with up to 8 client devices– PR1720 fieldbus transmitter

PR1720 transmitters– Modern field instrumentation for tank

and hopper scales– Type of ignition protection (PR1720

fieldbus transmitters): “non-sparking,”ATEX: II 3 GD EEx nA II T4 T100°C IP65

– Intrinsically safe load cell power supply– Fieldbus protocols, interface

(also analog output)– “Smart calibration“ via load cell data– Field housing: IP65

Discovery metal detector:– For detection of metal particles– Type of ignition protection,

ATEX: ll 3 D T80°C IP5X– Safeguards against machine damage

and downtimes – Optimal compliance with legal

requirements, e.g., HACCP– Assures product quality in compliance

with ISO9001

Load cells– Wide capacity range up to 300 t– Various designs (tension and bending

beam load cells, compression load cells,PanCake® level cells, specialty loadcells)

Zone

22

Expl

osiv

e Du

sts

Cate

gory

ll 3

D

20

Hazardous area

PC

PC

Non-hazardous area

Pallet scale + Option Y2

Flat-bed scale + Option Y2

Combics platform + Option Y2

Combics indicator+ Option Y2

IS…precision platform + Option Y2

Configurations with Combics and Option Y2 for zone 22

Configuration with Sartorius Discovery metal detector for zone 22


IS weighing platformsCombics platformCombics indicator

DiscoveryPC with QA systems,e.g., with SPCfWin


IUS|IUG pallet scaleIFSX|IFP flat-bed scale

21

Configuration with load cells in zone 22


Load cells, e.g., PR62… Fieldbus transmitterPR1720

PLC or PC

Discovery metal detector PR1720 fieldbus transmitterEX weigh cell

Aside from explosion-protected scales, zones1, 20 and 21 equipment configurationsrequire ATEX-compliant power supplies andZener barriers or interface converters for dataexchange in the non-hazardous area.

Flexibility in powering Sartorius productsfor use in zone 1, 20 or 21– In hazardous areas, the ambient conditions

for the power supply vary considerably. Sartorius has responded to these require-ments by offering explosion-protectedscales that are independent of a specificpower supply design. You can choose fromthe following power supplies that are avail-able in the various international versions:

– Power supply for installation in a hazardousarea (110…240 V)

– Rechargeable battery for installation in a hazardous area (110…240V)

– Power supply for installation in a non-hazardous area (110…240V)

– 24-volt module for installation in a non-hazardous or hazardous area (24 VDC);can also be installed in a control panel

Flexible data communication between hazardous area equipment and non-hazardous area peripheralsUsually, weighing equipment is connected toa report printer, a PC or a PLC located in thenon-hazardous area. Both the hazardous andthe non-hazardous area must be electricallyisolated from each other.

Sartorius offers various solutions for isolationof intrinsically safe from non-intrinsicallysafe circuits. These solutions are compatiblefor all Sartorius product families:

– Zener barriers for different applications– A universally configurable interface con-

verter that can also be installed in zone 2

Independently of the particular datainterface selected for the scale (RS-232C, RS-422, RS-485, TTY 20 mA) andthe transmission rate, Sartorius Zenerbarriers and interface converters enablecommunication over various distancesbetween peripherals in the non-hazardous area and the hazardous-areaequipment.

Up to 8 client weighing devices with anRS-485 data interface can be networkedin a hazardous area.

22

Typical weighing equipment configuration for zone 1 (II 2 G) and zone 21 (II 2 D)

Hazardous area II 2 G Nicht explosionsgefährdeter Bereich

Interface converter orZener barrier

e.g., FC scale Foot switch

PC

Data printer

PLC

Power supply(110V-230V)

24-Vmodule

24-Vmodule

Power supply(110V-230V)

Rechargeablebattery

ib


Typical weighing equipment configuration for zone 2 (II 3 G) and zone 22 (II 3 D)


PC

Data printer

PLCCombics platform + Option Y2 e.g., Combics

indicator +Option Y2


EN Official Journal of the European Communities28. 1. 2000 L 23/61

ANNEX I

CLASSIFICATION OF PLACES WHERE EXPLOSIVE ATMOSPHERES MAY OCCUR

Preliminary note

The following system of classification must be applied to places where precautions in accordance with Articles 3, 4, 7 and8 are taken.

1. Places where explosive atmospheres may occur

A place in which an explosive atmosphere may occur in such quantities as to require special precautions to protect thehealth and safey of the workers concerned is deemed to be hazardous within the meaning of this Directive.

A place in which an explosive atmosphere is not expected to occur in such quantities as to require special precautionsis deemed to be non-hazardous within the meaning of this Directive.

Flammable and/or combustible substances are considered as materials which may form an explosive atmosphere unlessan investigation of their properties has shown that in mixtures with air they are incapable of independentlypropagating an explosion.

2. Classification of hazardous places

Hazardous places are classified in terms of zones on the basis of the frequency and duration of the occurrence of anexplosive atmosphere.

The extent of the measures to be taken in accordance with Annex II, Part A, is determined by this classification.

Zone 0

A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas,vapour or mist is present continuously or for long periods or frequently.

Zone 1

A place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas,vapour or mist is likely to occur in normal operation occasionally.

Zone 2

A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas,vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Zone 20

A place in which an explosive atmosphere in the form of a cloud of combustable dust in air is present continously, orfor long periods or frequently.

Zone 21

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur innormal operation occasionally.

Zone 22

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur innormal operation but, if it does occur, will persist for a short period only.

Notes:

1. Layers, deposits and heaps of combustible dust must be considered as any other source which can form an explosiveatmosphere.

2. ‘Normal operation’ means the situation when installations are used within their design parameters.

competence for safety dust groups · temperature (cloud) and glow temperature (layer) of the...

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