atex approved oxygen analyzer

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  • ATEX explosion approved InSitu Oxygen AnalysersFred GumprechtM.D. ENOTEC GmbH

  • For the safe use of analyser systems in areas with explosion hazards, it is important to not only rely

    on the ATEX certificate.

    It is also important to realise where potential ignition sources are formed and that the equipment

    be ATEX tested under conditions similar to the expected process conditions.

    In the following presentation we will focus on InSitutype analysers with heated sensors which are a

    potential ignition risk.

  • ATEX explosion approved InSituanalyser at work.

  • The film has shown that the measurementof true flue gas values contribute to a safecombustion process.

    We will now focus on essential gas hazard arearelated safety requirements for an InSituanalyser itsself.

    ATEX approved probes for dust hazard areasare not dealt with here as they do require a different test and certification process.

  • Fast flue gas response

    Ignition protection for all gas conditions at the probe

    Essential safety relatedrequirements:

    Safety relevant components are easily inspected forfunctionality

    Foreseeable process conditions must be considered forATEX certification

  • Fast flue gas response

  • Fast flue gas response

    An OXITEC probe needs about 30 seconds in normal flue gas velocity.

    The green line shows the required flue gas response for safecombustion control

  • An example of a different probe construction principlewhich causes a slow flue gas response

    Test gas flow to a small sensor volume suggests fast responseFlue gas slowly displaces the test gas volumethrough two barriers, the probe filter and the flamearrestor

    Fast flue gas response

  • The sensor response to the flue gas composition is important for safe combustion control.

    The blue line shows a fast test gas response but an extremely slow flue gas response.

    Fast flue gas response

  • Ignition protection for all gas conditions at the

    probe

  • Important! All types of oxide ceramic sensors are electrically heated to 700C - 800C and present a potential ignition so urce!

    COe Sensor O2 Sensor

    T3 = Temperature classsurface temperature below 200C

    IIC = Explosion group (safe gap)hydrogen / acetylene

    Equipment category1 = qualified for zone 0, 1 and 22 = qualified for zone 1 and 23 = qualified for zone 2Kind of atmosphere G = gas D = dust II d IIC T3Device group

    I = mining II = others

    2 G EEx

    Corresponds to the European Ex-Standards(EN-50...)

    d = Flameproof enclosure explosion only inside the enclosure

    COMTEC KEX6001

    Ignition protection for all gas conditions at the probe

    ENOTEC probe - ATEX approved for all gas conditions

    Hot corrosive flue duct Ambient air

    Duct wall

  • Regular inspection of safety relevant components

  • Hot Corrosive Flue Gas Ambient AirDuct Wall

    Pressure tested 37 Bar Hottest Surface area 200C (T3) Visible filter & flame arrestor Corrosion resistant material Redundant probe thermocouple for failsafe probe

    heater controller

    Regular inspection of safety relevant components

    Easy disassembling for inspection purposes Certified construction Certified material Certified production

    Filter & flame arrestor

    Test gas portTerminal box

    ATEX approved ENOTEC construction principle

    Mounting flange

    Zirconia cell Heater

  • Surface temperature 450C (T1) Certified for two temperatures

    T1 and T6? Only 1 probe thermocouple No failsafe probe heater controller Non visible flame arrestors

    Less corrosion resistant materials Disassembling problematic Toxic materials used Reference air probe volume included for

    flame proof tests? Certified production and testing?

    Typical construction principle found on the world market

    Regular inspection of safety relevant components

    Hot Corrosive Flue Gas Ambient Air

  • Foreseeable process conditions must be

    considered for ATEX certification

  • The legal regulations demand that the testability and maintenance ability must be considered during the certifying process (94/9/EG, Appendix II, 1.0.3).

    All heated InSitu probes with non visible ignition protection relevant components do not allow the user a regular check. If hot corrosive flue gas is not considered by a test house as the normal operational ambient condition when testing these products, these products are suitable for ambient air measurement only.

    All heated InSitu probes with certificates, which do not specify foreseeable flue gas conditions have a certificate for ambient air conditions only. This certificate is invalid if this product is used in hot corrosive flue gas.

    The legal regulations demand that the foreseeable process conditions haveto be considered during the certifying process (94/9/EG, Appendix II, 1.0.4).

    Foreseeable process conditions must be considered for ATEX certification

  • The legal regulations demand that the entire equipment (e.g. an O2 measuring probe) is to be examined and certified as one unit. In each case an ATEX certificate must refer to the complete probe assembly.

    All probes, which are certified for two different temperature classifications (e.g. T1/T6) and for two different gas groups (e.g. EExd IIB/IIC), do not comply with the EU-Directives.

    All manufacturers who assemble probes using some ATEX approved components, such as flame arrestors or terminal boxes, do not comply with the EU-Directives. These probes are not qualified for hazardous areas installations, even if some Ex-markings remain on any components.

    All certified probes where a temperature class is mentioned, do require a certified failsafe temperature limitation.

    Foreseeable process conditions must be considered for ATEX certification

  • Responsibilities

  • The plant owner has the responsibility for safe operation of his plant.

    It is his responsibility to judge the explosion risks and to divide areas into zones accordingly.

    He must ensure that all installed equipment is suitable for safe plant operation under all foreseeable process conditions.

    He must ensure that all installed equipment is certified according to the regulations for all foreseeable process conditions before initial use.

    The equipment must be kept in a safe status by means of regular inspection and maintenance.

    Responsibilities

  • Responsibilities

    The plant owner has the responsibility for all arising damages.

  • The manufacturer of explosion protected equipment has the responsibility for mandatory tests as close as possible to foreseeable process conditions.

    Certification and documentation of the construction, the material and test procedures are required to ensure that each manufactured device complies with the certified design.

    Responsibilities

  • Do not put your trust only in certificates!

    We thank you for paying attention

    Look at all specifics of a product before using it!

    Install proven product quality for your plant safety.

    For more information, please contact us at the Multi Instruments booth

  • AppendixBasic information for your safe operation in Hazardous areas

  • Areas with risk of explosion are divided into zones, depending on frequency and duration of the occurrence of combustible atmosphere (Directive 1999/92/EG).

    Gases, Vapours, Mists Dusts (coal, flour, metal, finely ground powder)

    Zone 0 Zone 20

    Zone 1 Zone 21

    Zone 2 Zone 22

    Equipment with relevant Ex-protection can be safely operated in each zone according to its certification.

    Category 1 G Category 1 D

    Category 2 G Category 2 D

    Category 3 G Category 3 D

    Area, in which explosive atmosphere...

    is continuously, long-term or frequently existent (Guiding value, not standardised: more than 1000 h per year)

    in normal operations occasionally occurs (Guiding value, not standardised: 10 1000 h per year)

    in normal operations normally not or with only short-term occurrences(Guiding value, not standardised: less than 10 h per year)

    Devices of this category are to be designed and manufactured in such a way that...

    ignition sources, even in case of equipment faults which seldom arise, are to be avoided. Also if two faults arise within the equipment, it may not come to an ignition.

    In the event of frequently arising or expected disturbances (defects of the equipment) retain the necessary level of safety to ensure that no ignition source is created.

    ignition sources which can be expected and which can occur with normal usage, are avoided.

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    Zone 0

    Zone 1

    Zone 2

    Definition of Hazardous Areas into Zones

  • An explosion is the sudden chemical reaction (oxidation) of a flammable material with oxygen under release of high energy.

    Flammable Material

    Oxyg

    en

    Ignition

    SourceIgnition Triangle

    Explosion LimitAn explosion can only occur, if the flammable material is present within a certain concentration range. If the concentration is too small (too lean) or to high (too rich) no explosion takes place, but a slow oxidation without a visible flame may happen.

    SubstanceDesignation

    Lower Explosion Limit in Mixture with Air [Vol.%]

    Upper Explosion Limit in Mixture with Air [Vol.%]

    Acetylene 1,5 82

    Gasoline 0,6 8Natural Gas 4,5 13,5Carbon monoxide 12,5 75

    Three factors must be met to induce an explosion :

    The explosion limits depend on the ambient pressure and the oxygen content.

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    Definition of an Explosion

  • Device Group

    I Electrical apparatus for mining

    II Electrical apparatus for all remaining potentially explosive atmospheres

    Equipment Category

    1 = qualified for zone 0, 1 and 22 = qualified for zone 1 and 23 = qualified for zone 2

    G = gas D = dust

    Kind of Atmosphere

    Conformance Marking

    EEx The equipment corresponds to valid EN standards and is certified from a recognized European laboratory.

    Method of Protection

    d flameproof enclosuree increased safetyi intrinsic safetym encapsulationn type of protectiono oil immersionp pressurized apparatus q powder filling

    Explosion Group

    I firedamp endangered mine workings (methane)

    IIA experimental safe gap > 0,9 mmtypical gas: propane, gasoline

    IIB experimental safe gap 0,5 mm to 0,9 mmtypical gas: town gas, ethylene

    IIC experimental safe gap < 0,5 mmtypical gas: acetylene, hydrogen

    Max. surface temperature of equipment:T1 450CT2 300CT3 200CT4 135CT5 100CT6 85C

    III

    123

    GD

    EEx deimnopq

    IIIAIIBIIC

    T1T2T3T4T5T6

    Type-exami-nation tested

    (Probe)

    (Electronic Unit)

    ATEX, the European Ex-Marking

    Surface Temperature