IEC TC31 (Explosive Atmospheres) – Gas Detection as Method of Protection

Jon Miller Detector Electronics Corporation

Approvals Engineering Manager

Convener of IEC TC31 MT60079-29 (Gas Performance) IECEx USNC voting member (ISA Representative)

Chairman of UL STP 60079 SP12.13 (Gas Performance) Chairman of ISA SP92 (Toxic Gas Performance)

Agenda Combustible Gas Detection – Method of Protection 1) Codes & Standards 2) Technologies 3) Applications

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But, First the Basics 1) Process Control Gas concentration monitoring only

2) Risk Area Protection (IEC 60079-29)

• Alarm Notification • Equipment Shut-down • Ventilation Actuation

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‘Risk Area Protection’ using Gas Detection DOES mitigate risk of ignition in the classified area DOES NOT change the area classification

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Zone 2 Non-hazardous Zone 1

Point Detector

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Codes of Practice

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Gas Detection as Method of Protection

{gas detection + action = mitigation}

Product Standards

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Agenda Combustible Gas Detection - Method of Protection

1) Codes & Standards 2) Technologies 3) Applications

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Technologies

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Technologies (Catalytic, Point)

0% LFL

20% LFL

50% LFL

100% LFL

Gas

Clo

ud

75% LFL

Product images courtesy of New Cosmos Electric Co., Dräger, General Monitors, Honeywell, Det-Tronics

1) Concentration measurement at detector

5) Flow consideration with detector position

Air Flow Direction

3) %LFL output

2) Detector must be in the gas cloud for detection

Zone 1 Point

Detector

4) K-factor for target gas

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Technologies (Infrared, Point)

0% LFL

20% LFL

50% LFL

100% LFL

Gas

Clo

ud

1) Concentration measurement at detector

5) Flow consideration with detector position

Air Flow Direction

3) %LFL output

2) Detector must be in the gas cloud for detection

Zone 1 Point

Detector

4) Linearized for target gas

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Technologies (Infrared, Open Path)

1) Concentration measurement between two points

3) LFL-meter output (NOT actual concentration)

2) Detector need NOT be in the gas cloud for detection

4) Linearized for target gas

5) Perimeter detection (air flow coverage)

*** Intended to supplement (not replace) Point Detection ***

Gas

Clo

ud

0 LFL-meter

2.5 LFL-meter

5 LFL-meter

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12 Product images courtesy of New Cosmos Electric Co., Dräger, General Monitors, Honeywell, Det-Tronics

Technologies Summary

Technology Catalytic, Point Infrared, Open Path Infrared, Point

Advantages • Low initial cost • Hydrogen detection • Versatile, broad range

• Large area coverage • Fail safe • Infrequent calibration • Low maintenance

• Environmental superiority • Fail safe • Low cost of ownership • High reliability

Disadvantages

• Frequent calibration cycle • Susceptible to poisoning • Not fail safe, monthly

degradation

• Alignment challenges • LEL-m read out • Expensive

• No hydrogen detection

Agenda Combustible Gas Detection - Method of Protection

1) Codes & Standards 2) Technologies 3) Applications

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Application (Control Panel)

Safe Area

IEC 60079-29-1 Gas Controller

A spill evaporates or process piping leaks

Visible alarm

Audible alarm

As counter measure, increased ventilation activated

Zone 2 Room Ex

As counter measure, de-energize control panel when 40% LFL is detected within Zone 2 room

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1

3

Control Panel (non-hazardous)

(@40%LFL Alarm)

* Zone 1 Point

Detector

* Zone 1 Point

Detector

* Zone 1 Point

Detector (@20%LFL Alarm)

2 Upon detection of 20% LFL inside control panel de-energize control panel

* IEC 60079-29-1 Gas Detector

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Application (Interior Room)

Safe Area

IEC 60079-29-1 Gas Controller

A spill evaporates or process piping leaks

Visible alarm

Audible alarm Zone 2 Room Ex

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Non hazardous Room • Analyzer Room • Control Room • Office

(@40%LFL Alarm)

* Zone 1 Point

Detector

* Zone 1 Point

Detector

* Zone 1 Point

Detector

(@20%LFL Alarm)

Equipment

As counter measure, increased ventilation activated when 20% LFL detected in Zone 2 area.

Upon detection of 20% LFL inside non hazardous room, de-energize equipment

As counter measure, de-energize equipment when 40% LFL is detected within Zone 2 room

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2

3

* IEC 60079-29-1 Gas Detector

Clean Air

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Application (Low Ventilation Rate)

Safe Area

IEC 60079-29-1 Gas Controller

A spill evaporates

Visible alarm

Audible alarm

As counter measure, ventilation activated

Zone 1 Room Ex

As counter measure, power switched OFF

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1

2

Zone 2 Equipment EPL Gc • Variable speed drive • Control equipment • Power supply • Transformer

(@40%LFL Alarm)

* Zone 1 Point

Detector

* Zone 1 Point

Detector

* Zone 1 Point

Detector

(@20%LFL Alarm)

* IEC 60079-29-1 Gas Detector

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Application (Gas Detection + Action = Mitigation) R

isk

Ass

essm

ent

Risk – ignition from non-Ex rated equipment dangerous

safe

Existing Condition

Increase Ventilation

De-energize

Gas Detection

residual risk

risk reduction

necessary risk reduction

actual risk reduction

tolerable risk

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Gas

Det

ectio

n S

yste

m

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Application Summary

%LEL

20

40

Power ‘OFF’ Ventilation ‘ON’

Gas

det

ecto

r sig

nal

1st Alarm

2nd Alarm

Gas concentration decreases - countermeasure is effective

Gas concentration still rises - countermeasure not effective

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Questions Combustible Gas Detection - Method of Protection

1) Codes & Standards 2) Technologies 3) Applications

THANK YOU! 19

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