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

Transcription

1 IEC TC31 (Explosive Atmospheres) Gas Detection as Method of Protection Jon Miller Electronics Corporation Approvals Engineering Manager Convener of IEC TC31 MT (Gas Performance) IECEx USNC voting member (ISA Representative) Chairman of UL STP SP12.13 (Gas Performance) Chairman of ISA SP92 (Toxic Gas Performance)

2 Agenda Combustible Gas Detection Method of Protection 1) Codes & Standards 2) Technologies 3) Applications 2 Courtesy of Det-Tronics

3 But, First the Basics 1) Process Control Gas concentration monitoring only 2) Risk Area Protection (IEC ) Alarm Notification Equipment Shut-down Ventilation Actuation 3 Courtesy of Det-Tronics

4 Risk Area Protection using Gas Detection DOES mitigate risk of ignition in the classified area DOES NOT change the area classification Non-hazardous Zone 1 Zone 2 4 Courtesy of Det-Tronics

5 Codes of Practice Gas Detection as Method of Protection {gas detection + action = mitigation} 5 Courtesy of Det-Tronics

6 Product Standards 6 Courtesy of Det-Tronics

7 Agenda Combustible Gas Detection - Method of Protection 1) Codes & Standards 2) Technologies 3) Applications 7 Courtesy of Det-Tronics

8 Technologies 8 Courtesy of Det-Tronics

9 Technologies (Catalytic, ) 1) Concentration measurement at detector 2) must be in the gas cloud for detection Gas Cloud 75% LFL 100% LFL 50% LFL 3) %LFL output 4) K-factor for target gas Air Flow Direction 20% LFL Zone 1 0% LFL 5) Flow consideration with detector position Product images courtesy of New Cosmos Electric Co., Dräger, General Monitors, Honeywell, Det-Tronics 9

10 Technologies (Infrared, ) 1) Concentration measurement at detector 2) must be in the gas cloud for detection Gas Cloud 100% LFL 3) %LFL output 50% LFL 4) Linearized for target gas 20% LFL Air Flow Direction Zone 1 0% LFL 5) Flow consideration with detector position Product images courtesy of Dräger, General Monitors, Honeywell, Det-Tronics 10

11 Technologies (Infrared, Open Path) *** Intended to supplement (not replace) Detection *** 1) Concentration measurement between two points Gas Cloud 2) need NOT be in the gas cloud for detection 3) LFL-meter output (NOT actual concentration) 4) Linearized for target gas 5 LFL-meter 2.5 LFL-meter 0 LFL-meter 5) Perimeter detection (air flow coverage) Product images courtesy of Det-Tronics, General Monitors, Dräger 11

12 Technologies Summary Technology Catalytic, Infrared, Open Path Infrared, 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 Product images courtesy of New Cosmos Electric Co., Dräger, General Monitors, Honeywell, Det-Tronics 12

13 Agenda Combustible Gas Detection - Method of Protection 1) Codes & Standards 2) Technologies 3) Applications 13 Courtesy of Det-Tronics

14 Application (Control Panel) Ex Zone 2 Room Safe Area Audible alarm Visible alarm * Zone 1 Control Panel (non-hazardous) * Zone 1 * Zone 1 * IEC Gas 1 2 IEC Gas Controller (@20%LFL Alarm) As counter measure, increased ventilation activated Upon detection of 20% LFL inside control panel de-energize control panel A spill evaporates or process piping leaks 3 As counter measure, de-energize control panel when 40% LFL is detected within Zone 2 room Courtesy of Dräger & Det-Tronics 14 (@40%LFL Alarm)

15 Application (Interior Room) Ex Zone 2 Room Safe Area Audible alarm * Zone 1 Non hazardous Room Analyzer Room Control Room Office Equipment * Zone 1 * Zone 1 * IEC Gas Visible alarm IEC Gas Controller Clean Air A spill evaporates or process piping leaks (@20%LFL Alarm) 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 (@40%LFL Alarm) As counter measure, de-energize equipment when 40% LFL is detected within Zone 2 room Courtesy of Dräger & Det-Tronics

16 Application (Low Ventilation Rate) Ex Zone 1 Room Safe Area Audible alarm * Zone 1 * IEC Gas Visible alarm IEC Gas Controller * Zone 1 Zone 2 Equipment EPL G c Variable speed drive Control equipment Power supply Transformer * Zone 1 1 (@20%LFL Alarm) As counter measure, ventilation activated A spill evaporates 2 (@40%LFL Alarm) As counter measure, power switched OFF 16 Courtesy of Dräger & Det-Tronics

17 Application (Gas Detection + Action = Mitigation) dangerous Risk ignition from non-ex rated equipment Risk Assessment Gas Detection System Existing Condition Gas Detection Increase Ventilation De-energize risk reduction actual risk reduction necessary risk reduction residual risk tolerable risk safe 17 Courtesy of Dräger & Det-Tronics

18 Application Summary Ventilation ON Power OFF Gas detector signal %LEL 40 2nd Alarm 20 1st Alarm Gas concentration decreases - countermeasure is effective Gas concentration still rises - countermeasure not effective 18 Courtesy of Dräger & Det-Tronics

19 Questions Combustible Gas Detection - Method of Protection 1) Codes & Standards 2) Technologies 3) Applications THANK YOU! 19 Courtesy of Det-Tronics