A Performance Based Approach to Fire and Gas Detector … · 2020. 7. 17. · • ISA-TR84.00.07-2018 – Guidance on the evaluation of fire, combustible gas and toxic gas effectiveness

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A Performance Based Approach to Fire and Gas Detector Mapping and Why it Matters

Manages Fire and Gas Systems (FGS) mapping & Hazardous Area Classification (HAC) services at BakerRisk. 15+ years of experience in the process industry with 10+ years in the field of fire and gas detectors. Extensive experience with various phases of the ISA84/IEC61511 functional safety life cycle. A continuous member and leader of ISA at the student, local, and international level since 2001.

www.BakerRisk.com

Presenter: Murtaza Gandhi

Copyright BakerRisk. All rights reserved.

Presenter: Murtaza I. Gandhi, P.E.Principal Engineer, BakerRisk


July 16, 2020Copyright BakerRisk. All rights reserved.

[email protected]

Scenario Coverage Approach Consequence-Based Fire and Gas Detector Mapping

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Risk Based Prioritization of Detectors

Importance of Validating Models with Testing

Gas Detector Mapping for a Toxic Shelter

Key Takeaways

BakerRisk Webinar Series, F&G Detector Mapping 4

1. Why F&G detection studies? i. And a brief background on mapping

2. Methodology: Consequence and Risk-Based Approach3. Research on Scenario Coverage

o What’s happening in the industry? o BakerRisk work process for F&G mappingo Demo test (including NFPA)

4. Gas Detection in Toxic Shelters

Outline


Why F&G detection studies? And a brief background on mapping.

Why F&G Detection Studies?


F&G Detection System facilitates a prompt mitigation response as process units become less populated

Why F&G Detection Studies?

Detectors

Gas

Fire

Acoustic

Other End User

How many? Where to locate?

Consequence Models

Risk Calculations

BakerRiskF&G Studies

F&GTool©


What’s Happening in the Industry?

• What makes F&G Studies difficult?o HSE 8 years of offshore data – 60% of known releases were detectedo Current technical industry standards

• API Pub 2031 (1991)• IEC 60079• ISA TR84.00.07• Most clients have internal standards• Best industry practice

o Traditional studies• Experience based • CFD modeling involves high cost to place very few detectors


Definitions (ISA TR84.00.07)

• Geographic Coverage : The fraction of the geometric area or volume of a defined monitored process area that, if a hazard were to occur in a given geographic location, would be detected considering the defined voting arrangemento In other words: % of area covered

• Scenario Coverage : The fraction of the hazard scenarios from process equipment within a defined and monitored process area that can be detected considering the frequency and magnitude of the hazard scenarios and the defined voting arrangemento In other words : % of scenarios detected

BakerRisk’s F&G Studies and F&GTool©

• BakerRisk’s F&G studies assist our clients in the placement and optimization of fire and gas detectors.

• We use F&GTool©, a proprietary software developed by BakerRisk.o Allows detector placement and coverage to be evaluated and viewed in a 3D environment.o Allows consequence and risk results to be imported and used to place and optimize detectors.


Methodology:Consequence- and Risk- Based Approach

Define Performance

Criteria

Model Prep for Site Visit

(CAD Drawings,

P&ID review, etc.)

Import Consequence

and Risk Results

Site Visit

3D Model Development

Detector Layout

Generation, Optimization,

and Prioritization (if needed)

Generate Report

Typical F&G Studies WorkflowExisting

Consequence/Risk Models

Iterative Process


Fire and Gas Detection

• Fire and gas detectors are located based on consequence and risk contours, client guidelines, and industry standards.

• Gas detectorso Point gas detectors are given coordinates and a height to show a physical location in 3Do Line detectors are given coordinates and a height to allow them to interact with the 3D modelo Acoustic detectors are given coordinates and a height to allow them to interact with 3D model

• Fire Detectorso Conical flame detectors , heat detectors and fusible plugs


F&G Model

3D model is built with plot plan and site visit data

Flammable, toxic, and fire scenarios are imported from

Consequence Models

Detector locations are optimized and coverage calculated per risk calcs


Completed Model – 3D View


Plot plan of the unit

Physical survey

Develop 3D model

Completed model

Model Development


Plot Plan


Process Facility

Residential Campsite

Complete Model – 2D


Complete Model – 3D


Flammable Contours


Thermal Contours


Example Flammable Gas Detection


Example Fire Detection


Completed Model – 2D


Completed Model – 3D


Risk Based Approach

• ISA TR84.00.07

Three main components:1. Detection Coverage2. FG system availability3. Mitigation Effectiveness


Risk Based Approach

• Quantitative Risk Analysis (QRA)o Use QRA Societal or Individual Risk Results to calculate the detector priorityo Helps prioritizing the implementation of detectors in a phased approacho Beneficial in performing cost benefit analysis of adding detection

Classification Societal Risk Threshold (fatalities/year)

High >1E-4Significant >1E-5Suggested

BakerRisk Research on Scenario Coverage

BakerRisk Test Case Study

•74 tests•Test duration between 1 and 1.5 minutesSetup

•Saturated propane•1/2″, 3/4″ , 1″ releasesRelease

•5 Directions•Horizontal, West, East, Up, DownOrientations

•14 detectors•Located 60 to 200 feet from release point•3 different manufacturers

Detectors


BakerRisk Test Case Study (cont.)Te

st 1

-5

Calibration of the difference in response with and without weather baffles

Test

6 –

10

Calibration of detector response from different manufacturer detectors 3 detectors were placed very close to each other in the direction of the release

Test

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–74

Conducted randomly to determine the response for various release sizes, orientation and weather conditions.

Tests were performed in late morning and afternoon, night, and early morning to capture different wind conditions


BakerRisk Test Case Study (cont.)

• For this presentation, ½″ and ¾″ releases are considered

• A total of 58 tests were conducted for ½″ and ¾″ releases

• Detectors were not moved throughout these tests to ensure proper comparison

• All detectors were located at 1.5ft

DOWNWIND VERTICAL (UP) CROSSWIND (WEST)

CROSSWIND (EAST)

VERTICAL (DOWN)

ORIENTATION OF ½″ , ¾″ TESTS


BakerRisk Test Case Study Results

• Horizontal release downwind


BakerRisk Test Video: 0.5-inch Horizontal Case


Case Study – Scenario Coverage

• Considerations in the calculationso Initiating event frequency of the release occurring is 1o Probability of wind in the direction of release is considered 1 (winds were steady

from south-southwest, predominant wind direction)

• Based on the above considerations, scenario coverage was calculated for each of the 5 release directions and then for the overall scenario of a release occurring in any of the 5 directions under different wind conditions


Case Study - Results

Direction Total Tests Scenario Coverage 1oo1 Scenario Coverage 2oo2

Horizontal – downwind 14 100% 100%

Vertical – Up 10 0% 0%

West – crosswind 11 18% 18%

East – crosswind 11 82% 73%

Vertical - Down 12 100% 92%

All directions 58 62% 59%

Direction Total TestsScenario

Coverage 1oo14Scenario Coverage

2oo14

Horizontal – downwind 14 100% 100%

Vertical – Up 10 0% 0%

West – crosswind 11 18% 18%

East – crosswind 11 82% 73%

Vertical - Down 12 100% 92%

All directions 58 62% 59%

The scenario coverage for release in predominant wind direction is 100% while for multiple release directions drops to 60% overall


NFPA Test Results –Saturated Propane 0.3 kg/s (Medium Velocity Nozzle)


Toxic Gas Detection in a Shelter

Toxic Shelter


Toxic Gas Detection


F&G as a Service

Fire & Gas Detection and Fire Protection


References

• ISA-TR84.00.07-2018 – Guidance on the evaluation of fire, combustible gas and toxic gas effectiveness

• “Approaches to calculate scenario coverage”, ISA PCS 2015, Gandhi et al• “Build on your facility siting and QRA Investment: Designing an effective detection and

mitigation system”, AIChe GCPS 2019, Gandhi et al• “Toxic gas detection in ammonia plants for Shelter-In-Place”, 61st Ammonia Conference,

Sarrack et al• “Quantitative evaluation of fire detection coverage and mitigation effectiveness”, ISA PCS

2018, Black et al• “Vapor mitigation testing using fixed water spray system”, FPRF, Gandhi et al

(https://www.nfpa.org/News-and-Research/Data-research-and-tools/Hazardous-Materials/Vapor-mitigation-testing-using-fixed-water-spray-system)

• “Shelter-in-Place, reducing risk from toxic impacts”, Sarrack et al (https://www.bakerrisk.com/news/launch-of-best-practice-guidance-series-by-bakerrisk/)


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[email protected] 281-822-3100www.bakerrisk.com

www.BakerRisk.com

Murtaza Gandhi


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Upcoming BakerRisk Webinar:API Recommended Practice 1173, Pipeline Safety Management Systems

www.BakerRisk.com

Date: September 10, 2020

Presenter: Stephanie Salazar


Slide Number 1A Performance Based Approach to Fire and Gas Detector �Mapping and Why it MattersSlide Number 3Key TakeawaysOutlineWhy F&G detection studies? �And a brief background on mapping.Why F&G Detection Studies? Why F&G Detection Studies? What’s Happening in the Industry? Definitions (ISA TR84.00.07)BakerRisk’s F&G Studies and F&GTool©Methodology:�Consequence- and Risk- Based ApproachTypical F&G Studies WorkflowFire and Gas DetectionF&G ModelCompleted Model – 3D ViewModel DevelopmentPlot PlanComplete Model – 2DComplete Model – 3DFlammable ContoursThermal ContoursExample Flammable Gas DetectionExample Fire DetectionCompleted Model – 2DCompleted Model – 3DRisk Based ApproachRisk Based ApproachBakerRisk Research on Scenario CoverageBakerRisk Test Case StudyBakerRisk Test Case Study (cont.)BakerRisk Test Case Study (cont.)BakerRisk Test Case Study ResultsBakerRisk Test Video: 0.5-inch Horizontal CaseCase Study – Scenario CoverageCase Study - ResultsNFPA Test Results – �Saturated Propane 0.3 kg/s (Medium Velocity Nozzle)Toxic Gas Detection in a ShelterToxic ShelterToxic Gas DetectionF&G as a ServiceFire & Gas Detection and Fire ProtectionReferencesSlide Number 47Slide Number 48

Documents

A Performance Based Approach to Fire and Gas Detector … · 2020. 7. 17. · • ISA-TR84.00.07-2018 – Guidance on the evaluation of fire, combustible gas and toxic gas effectiveness