clean agent system designs

8/9/2019 Clean Agent System Designs

1/63

Clean Agent System DesignClean Agent System Design

Eric Forssell and Scott HillEric Forssell and Scott Hill

Hughes Associates, Inc.Hughes Associates, Inc.

(410) 737(410) 737--86778677

www.haifire.comwww.haifire.com

NFPA World Fire Safety Congress & ExpoNFPA World Fire Safety Congress & Expo

May 14, 2001May 14, 2001


2/63

ObjectiveObjective

Discuss specific issues affecting clean agentDiscuss specific issues affecting clean agentsystem design and system reliabilitysystem design and system reliability

-- Extinguishing ConcentrationsExtinguishing Concentrations

-- Safety/Design FactorsSafety/Design Factors-- Concentration/Exposure LimitsConcentration/Exposure Limits

-- Design SoftwareDesign Software

-- Thermal DecompositionThermal Decomposition

-- Agent RetentionAgent Retention

-- Enclosure Pressure and VentingEnclosure Pressure and Venting


3/63

What are clean agents?What are clean agents?

Definition: No residue or collateral damageDefinition: No residue or collateral damageresulting from discharge of agent.resulting from discharge of agent.

Historically: Carbon dioxide and Halon 1301 wereHistorically: Carbon dioxide and Halon 1301 were

the agents of choice. Ban on production of Halonthe agents of choice. Ban on production of Halon1301 due to contribution to stratospheric ozone1301 due to contribution to stratospheric ozone

depletion.depletion.

Current agents include a variety of halocarbon andCurrent agents include a variety of halocarbon and

inert gasesinert gases


4/63

ApplicationsApplications

High system cost justified by high value ofHigh system cost justified by high value ofprotected space or protected equipment beingprotected space or protected equipment being

mission/process criticalmission/process critical

Typical applications: TelecommunicationsTypical applications: TelecommunicationsEquipment, Computer/Electronics Equipment,Equipment, Computer/Electronics Equipment,

Control Rooms, Process Critical Equipment,Control Rooms, Process Critical Equipment,

Shipboard and OffShipboard and Off--shore Machinery Roomsshore Machinery Rooms


5/63

How do clean agents work?How do clean agents work?

Increasing the heat capacity of the fireIncreasing the heat capacity of the fireenvironment, resulting in increased amounts ofenvironment, resulting in increased amounts of

energy required to raise the temperature of theenergy required to raise the temperature of the

incoming air to the flame temperature.incoming air to the flame temperature. Displacing oxygen, resulting in reduced heatDisplacing oxygen, resulting in reduced heat

production.production.

Undergoing endothermic (energy absorbing)Undergoing endothermic (energy absorbing)

decomposition reactions in the presence of thedecomposition reactions in the presence of the

flame.flame.


6/63

Setting the DesignSetting the Design

ConcentrationConcentration

Establish the extinguishing concentrationEstablish the extinguishing concentration-- By test: Agent and fuel specificBy test: Agent and fuel specific

Use appropriate safety factorUse appropriate safety factor

Include any design factorsInclude any design factors

DC = (EC * SF) + DFDC = (EC * SF) + DF


7/63

ExtinguishingExtinguishing

ConcentrationConcentration

NFPA 2001, 2000 Edition:NFPA 2001, 2000 Edition:-- Class AClass A

UL 2127 and UL 2166UL 2127 and UL 2166

Wood crib in 100 mWood crib in 100 m33 enclosureenclosure

Plastic fuel array in 100 mPlastic fuel array in 100 m33 enclosureenclosure

-- Class BClass B Cup burnerCup burner

Confirmed for a few fuels in larger scale tests (ULConfirmed for a few fuels in larger scale tests (UL

and IMO)and IMO)


8/63

Class A TestsClass A Tests

UL 2127 and UL 2166UL 2127 and UL 2166-- 3 types of polymeric materials (PMMA, PP,3 types of polymeric materials (PMMA, PP,

and ABS)and ABS)

-- Difficult plastics to extinguishDifficult plastics to extinguish

-- 4 sheet array4 sheet array

-- Heptane or hot surface ignitionHeptane or hot surface ignition


9/63

UL Class A TestUL Class A Test

ArrangementArrangement

305mm

(12")

89mm

(3.5

")

305mm

(12")

951mm(37.5")

CinderBlock

PolycarbonateBaffles

Load CellDrip Tray

Channel Iron FrameCovered With SteelSheet on Top and Two Sides

AluminumAngle Frame

3.2mm (1/8") Allthread RodFuel Support

381mm (15")

254mm (10")254mm (10")

533mm

(21")

76mm(3")

127mm(5")

851mm

(33.5

")

32mm(1")

LoadCell

610 mm (24")

203mm x 406mm x 9.53mm

(8" x 16" x ")Plastic Sheet

a

12mm (")

12

mm

(")

Ignitor Pan


10/63

Cup Burner ApparatusCup Burner Apparatus85 2 mm85 2 mm

ChimneyChimney

535 25 mm535 25 mm

235 mm235 mm

DiffuserDiffuser

Fuel InletFuel Inlet Air/Agent InletAir/Agent Inlet

E ti i hi C t tiE ti i hi C t ti


11/63

Extinguishing ConcentrationExtinguishing Concentration

Differences for HeptaneDifferences for Heptane

Agent ISO Values Other ISO Burner

Values

Difference

(%)

IG-01 (Ar) 37.5 40.8 8.8

IG-1 (N2) 33.6 30.2 11.3

IG-541 33.8 31.9, 30.6 10.4

IG-55 32.3

FC-3110 5.9 5.3 11.3

HFC-23 12 12.3 2.5

HFC-227ea 6.6 6.6 0


12/63

Effect of RadiativeEffect of Radiative

FeedbackFeedback

radq.

TTFF11 (Bulk)(Bulk)

radq.

TTFF22(Bulk)(Bulk)

TTFF22> T> TFF11


13/63

ExtinguishingExtinguishing

Concentration SummaryConcentration Summary

Extinguishing concentration determined by testExtinguishing concentration determined by test-- Variability in testingVariability in testing

Radiative feedback may affect extinguishingRadiative feedback may affect extinguishing

concentrationconcentration-- LongLongpreburnpreburn timestimes

-- Metal surfacesMetal surfaces

Designer must determine how hazard relates to theDesigner must determine how hazard relates to the

method for determining the extinguishingmethod for determining the extinguishing

concentrationconcentration


14/63

Safety FactorsSafety Factors

NFPA 2001, 2000 EditionNFPA 2001, 2000 Edition-- 30%30%Class B, Manually activatedClass B, Manually activated

-- 20%20%Class AClass A

-- 10%10%InertingInerting

-- Design FactorsDesign Factors

ISO 14520, First Edition (August 2000):ISO 14520, First Edition (August 2000):-- 30%30%Class A and BClass A and B

-- 10%10%InertingInerting


15/63

Safety FactorsSafety Factors

Design deficienciesDesign deficiencies Installation deficienciesInstallation deficiencies

Uncertainty in extinguishing concentrationUncertainty in extinguishing concentration Special conditionsSpecial conditions


16/63

Design FactorsDesign Factors

Additional quantity of agentAdditional quantity of agent Intent is to increase system reliabilityIntent is to increase system reliability

Account for specific conditionAccount for specific condition-- Number of teesNumber of tees-- Enclosure pressureEnclosure pressure

-- Unclosable openingsUnclosable openings-- Enclosure and fuel geometryEnclosure and fuel geometry

-- ObstructionsObstructions


17/63

Prediction AccuracyPrediction Accuracy

Halocarbons (UL 2166)Halocarbons (UL 2166)

-- Mass 10% withMass 10% with

standard deviation lessstandard deviation less

than 5than 5

-- Discharge time 1Discharge time 1

secondsecond

-- Nozzle pressure 10%

Inert Gases (UL 2127)Inert Gases (UL 2127)

-- Volume of agent 10%Volume of agent 10%

with standard deviationwith standard deviation

less than 5less than 5

-- Discharge time 10Discharge time 10

secondsseconds

-- Nozzle pressure 10%Nozzle pressure 10% Nozzle pressure 10%


18/63

Tee Design FactorTee Design Factor

For systems protecting multiple hazardsFor systems protecting multiple hazards For each hazardFor each hazard

-- Start at point where pipe system enters theStart at point where pipe system enters the

hazard and count the number of tees in the flowhazard and count the number of tees in the flow

path back to the agent supplypath back to the agent supply

-- also include any tee in the hazard that suppliesalso include any tee in the hazard that suppliesagent to another hazardagent to another hazard

-- do not include manifold teesdo not include manifold tees


19/63

Tee Design Factor (cont.)Tee Design Factor (cont.)

Use the hazard with the highest tee countUse the hazard with the highest tee count Not necessary if system passes a dischargeNot necessary if system passes a discharge

testtest

P b bilit Di t ib ti fP b bilit Di t ib ti f


20/63

Probability Distribution forProbability Distribution for

Agent Mass for 2 to 20 TeesAgent Mass for 2 to 20 Tees

0

2

4

6

8

10

12

14

16

18

20

22

0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45

Normalized Mass

RelativeProbability

Experiment Standard Deviat ion = 0.0304

2 Tees2 Tees

20 Tees20 Tees

4 Tees4 Tees

Calculated Agent QuantityCalculated Agent Quantity


21/63

Calculated Agent QuantityCalculated Agent Quantity

Probability Distribution:Probability Distribution:

A System with 8 Tees (Std. Dev. = 0.0608)A System with 8 Tees (Std. Dev. = 0.0608)

0

2

4

6

8

10

12

14

16

0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30

Measured Agent Quantity (normalized by the predicted agent quantity)

RelativeP

robability

99%

1%

WithoutWithout

Additional AgentAdditional Agent

WithWith

Additional AgentAdditional Agent


22/63

DESIGN FACTOR

TEE COUNT

HALOCARBON

DESIGN FACTOR

INERT GAS DESIGN

FACTOR

0-4 0.00 0.00

5 0.01 0.00

6 0.02 0.00

7 0.03 0.00

8 0.04 0.00

9 0.05 0.01

10 0.06 0.01

11 0.07 0.02

12 0.07 0.02

13 0.08 0.03

Design Factor for TeesDesign Factor for Tees


23/63

ExampleExample

Hazard 2Hazard 2

Hazard 1Hazard 1

Tee count of 8 teesTee count of 8 tees

for Hazard 2for Hazard 2 4%4%

additional agentadditional agent

requiredrequired

Alternate layout toAlternate layout to

reduce tee count to 4reduce tee count to 4teestees no additionalno additional

agent required.agent required.

Hazard 1Hazard 1

Hazard 2Hazard 2


24/63

Enclosure Pressure DesignEnclosure Pressure Design

FactorFactor

Agent quantity must be adjusted if ambientAgent quantity must be adjusted if ambientenclosure pressure varies by more than 11enclosure pressure varies by more than 11

percent from standard sea level pressurespercent from standard sea level pressures

Pressure may be affected by factors otherPressure may be affected by factors other

than elevationthan elevation

-- Hyperbaric chambers, mines, facilities whereHyperbaric chambers, mines, facilities whereventilation fans are used to create artificiallyventilation fans are used to create artificially

higher or lower pressureshigher or lower pressures


25/63

Additional Design FactorsAdditional Design Factors

Unclosable openingsUnclosable openings

-- Compensate by adding agent and extending dischargeCompensate by adding agent and extending discharge

timetime

Enclosure and fuel geometryEnclosure and fuel geometry-- Unusual geometries are typically addressed throughUnusual geometries are typically addressed through

nozzle placement and additional agentnozzle placement and additional agent

-- FullFull--scale machinery space tests showed that for a largescale machinery space tests showed that for a largeenclosure with a complex obstructed geometry, agentenclosure with a complex obstructed geometry, agent

concentrations varied 20% in the enclosureconcentrations varied 20% in the enclosure


26/63

Additional Design FactorsAdditional Design Factors

ObstructionsObstructions-- Obstructions such as ducts, cables, lightObstructions such as ducts, cables, light

fixtures, etc. can block or impede agentfixtures, etc. can block or impede agent

discharge which can affect mixingdischarge which can affect mixing-- Address with nozzle placement and/orAddress with nozzle placement and/or

additional agentadditional agent


27/63

Concentration/ExposureConcentration/Exposure

LimitsLimits

All efforts are made to avoid anyAll efforts are made to avoid anyunnecessary exposureunnecessary exposure

-- Time delays allow for egress from areaTime delays allow for egress from area

-- Warning signals inside and outside of enclosureWarning signals inside and outside of enclosure

indicate system activationindicate system activation


28/63


LimitsLimits

For halocarbons, maximum safe exposureFor halocarbons, maximum safe exposurelimit determined by cardiac sensitizationlimit determined by cardiac sensitization

-- Determined by testing with dogs stressed withDetermined by testing with dogs stressed with

adrenalineadrenaline-- NOAELNOAEL --No Observable Adverse Effect LevelNo Observable Adverse Effect Level

-- LOAELLOAEL -- Lowest Observable Adverse Effect LevelLowest Observable Adverse Effect Level

-- PBPKPBPK -- PhysiologicallyPhysiologically--Based Pharmacokinetic, modelBased Pharmacokinetic, modelused to account for rate of uptake of agent into theused to account for rate of uptake of agent into the

blood streamblood stream


29/63


LimitsLimits

For inert gases, maximum safe exposureFor inert gases, maximum safe exposurelimit determined by oxygen displacementlimit determined by oxygen displacement

-- Oxygen concentration of 12% by volume approximatesOxygen concentration of 12% by volume approximates

NOAEL type significanceNOAEL type significance-- Oxygen concentration of 10% by volume approximatesOxygen concentration of 10% by volume approximates

LOAEL type significanceLOAEL type significance

-- The PBPK model does not apply to inert gasesThe PBPK model does not apply to inert gases


30/63

Maximum ConcentrationsMaximum Concentrations

Normally occupied enclosuresNormally occupied enclosures-- Halocarbon agentsHalocarbon agents

Up to NOAELUp to NOAEL

Up to LOAEL with means to limit exposure to timeUp to LOAEL with means to limit exposure to timelimits from PBPK modellimits from PBPK model

-- Inert gasesInert gases

Up to 43% (12% oxygen) with means to limitUp to 43% (12% oxygen) with means to limit

exposure to 5 minutesexposure to 5 minutes


31/63

Maximum ConcentrationsMaximum Concentrations

Normally unoccupied enclosuresNormally unoccupied enclosures-- Halocarbon agentsHalocarbon agents


exposure to time limits from PBPK modelexposure to time limits from PBPK model

-- Inert gasesInert gases


exposure to 3 minutesexposure to 3 minutes


exposure to 30 secondsexposure to 30 seconds

What is the Purpose of FlowWhat is the Purpose of Flow


32/63

What is the Purpose of FlowWhat is the Purpose of Flow

Calculation Software?Calculation Software? Predict system discharge performance for designPredict system discharge performance for design

purposespurposes-- Discharge time, nozzle pressure, nozzle agent quantityDischarge time, nozzle pressure, nozzle agent quantity

-- Generally, systems are not discharge testedGenerally, systems are not discharge tested

Insure system meets criteriaInsure system meets criteria-- NFPA 2001, Listing or approvalNFPA 2001, Listing or approval

-- AHJ, OEMAHJ, OEM

Software is a toolSoftware is a tool

S l S tS l S t


33/63

Sample SystemSample System

P t ti f MiP t ti f Mi


34/63

Protection from MisuseProtection from Misuse

Initial listing/approval and followInitial listing/approval and follow--up serviceup service

Acceptable hardware built inAcceptable hardware built in Error and Warning messagesError and Warning messages

Trained and competent userTrained and competent user Review of the designReview of the design

--

AHJ/InsuranceAHJ/Insurance

-- OwnerOwner


35/63

Additional FeaturesAdditional Features

Export pipe layout to Cad packagesExport pipe layout to Cad packages

Ability to lock diameter for individual pipeAbility to lock diameter for individual pipe

segmentssegments

-- Particularly helpful with retrofitsParticularly helpful with retrofits

Design specific helpDesign specific help


36/63

Verification of FlowVerification of Flow

Calculation MethodCalculation Method

Series of discharge tests conducted to verifySeries of discharge tests conducted to verify

predictionspredictions

Tests also establish other system limitsTests also establish other system limits

-- minimum and maximum orifice area ratiosminimum and maximum orifice area ratios-- tee types, orientations, and split ratiostee types, orientations, and split ratios

-- maximum arrival time imbalancemaximum arrival time imbalance

-- maximummaximum runoutrunout time imbalancetime imbalance

-- maximum pipe volume to agent liquid/cylinder volumemaximum pipe volume to agent liquid/cylinder volume

ratio (percent in pipe)ratio (percent in pipe)


37/63

PrePre--Witness TestsWitness Tests

3 and 4 nozzle tests3 and 4 nozzle tests

Each test with multiple limits includedEach test with multiple limits included

All limits hit at least onceAll limits hit at least once

Submittal package put togetherSubmittal package put together

-- software outputsoftware output

-- asas--built drawingsbuilt drawings-- experimental dataexperimental data

All tests must pass criteriaAll tests must pass criteria


38/63

Witness TestsWitness Tests

UL/FM presentUL/FM present

2 of the pre2 of the pre--witness tests chosenwitness tests chosen

-- ReRe--run the tests, results must be acceptablerun the tests, results must be acceptable

At least three new blind tests are runAt least three new blind tests are run-- The limits for a test are chosenThe limits for a test are chosen

-- The test is laid out on the computerThe test is laid out on the computer-- The system is constructed and the test runThe system is constructed and the test run

-- All tests must pass criteriaAll tests must pass criteria


39/63

Limits for a Witness TestLimits for a Witness Test

Minimum fill densityMinimum fill density

Maximum discharge timeMaximum discharge time

Maximum run out time imbalanceMaximum run out time imbalance

Minimum pipe flowrateMinimum pipe flowrate

Minimum nozzle area ratioMinimum nozzle area ratio

50:50 bull tee50:50 bull tee

85:15 side tee85:15 side tee

P t E ti i h t


40/63

PostPost--ExtinguishmentExtinguishment

Enclosure EnvironmentEnclosure Environment

Thermal Decomposition ProductsThermal Decomposition Products

-- For Halocarbon Agents, Halon 1301, FMFor Halocarbon Agents, Halon 1301, FM--200,200,

FEFE--25, and FE25, and FE--13, production of HF is the13, production of HF is the

primary concern.primary concern.-- For Inert Gas Agents, IGFor Inert Gas Agents, IG--100, IG100, IG--01, IG01, IG--55,55,

IGIG--541 and CO2, there are no thermal541 and CO2, there are no thermal

decomposition products formed.decomposition products formed.

P tP t E ti i h tE ti i h t


41/63


Enclosure EnvironmentEnclosure Environment-- Resulting TDP concentration is dependentResulting TDP concentration is dependent

upon:upon:

Fire Size to Enclosure Volume Ratio.Fire Size to Enclosure Volume Ratio.

Discharge Time.Discharge Time. Safety Factor (Utilizing higher than minimumSafety Factor (Utilizing higher than minimum

concentration can reduce amount formed).concentration can reduce amount formed).

E.W.Forssell, et al, An Evaluation of the International Maritime Organizations Gaseous Agent Test Protocol,

Fire Technology, 2001


42/63

Fire Size to Room Volume Ratio (kW/m3)

0 2 4 6 8 10 12 14 16 18

HFConcentra

tion(ppm)

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

Approximate HF Production Correlation

(5%)(12 %) Ansul (12 %) NAFGT

(7%)

(8.5%) (9%)

(8.6%) K-F (8.6%) M/S-F

(8.6%) Chemetron

(3.7%)

(7.9%)

(6.2%)

(14.4%)

(6.2%)

(7.9%)

(14.4%)

(7.2%)

(13.2%)(5%)

(7.0%)

(6.0%)

(16%)

Agent

Halon 1301NAF-SIII

CEA-410

CEA-308

FM-200

FE-13

IMO Protocol (500 m3) (1.2 m

3) (28 m

3)

NASAUSCG (526 m

3)

(8.8%)

(5%)

(7.6%)

(12%)

NRC (121 m3)

gy

P tP t E ti i h tE ti i h t


43/63


Enclosure EnvironmentEnclosure Environment-- Primarily hazard is to personnel as equipment isPrimarily hazard is to personnel as equipment is

generally more tolerant than humans to exposuresgenerally more tolerant than humans to exposures

-- Dangerous Toxic Loading,Dangerous Toxic Loading, DTLHumanDTLHuman, representing, representing

the threshold for life threatening exposures estimatedthe threshold for life threatening exposures estimated

byby MeldrumMeldrum as 12,000as 12,000ppmppm--minutes or an exposure tominutes or an exposure to12001200ppmppm HF for 10 minutes.HF for 10 minutes.

MeldrumMeldrum, M., Toxicology of Substances in Relation to Major, M., Toxicology of Substances in Relation to Major

Hazards: Hydrogen Fluoride, Health and Safety ExecutiveHazards: Hydrogen Fluoride, Health and Safety Executive(HSE) Information Centre, Sheffield S37HQ, England, 1993.(HSE) Information Centre, Sheffield S37HQ, England, 1993.

-- Early detection and fast suppression key to limitingEarly detection and fast suppression key to limiting

effects.effects.

H a z a r d a s s e s s m e n t o f H F c o n c e n t ra t io n s


44/63

d u r in g G L C C E D P t e s tin g

E x p o s u r e T im e ( m in )

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

Average

HFConcentration(ppm

)

0

1 0 0 0

2 0 0 0

3 0 0 0

4 0 0 0

5 0 0 0

M a g T a p e ( c )M a g T a p e ( o )

P a p e r ( T L )

P a p e r ( B L )

C ir c u i t B o a r d

W ir e /n - H e p t a n e

L C5 0

G u i n e a P ig

R a t

R a t

R a t

M o n k e y

R a t

M o u s e

E s t im a t e d L C 5 0 , M a m m a l

E s t im a te d D T L , H u m a n

[ H u g h e s A s s o c ia t e s , I n c ., "H a z a r d A s s e s s m e n t o f T h e r m a l D e c o m p o s it io n P r o d u c ts o f F M - 2 0 0T M

in E l e c tr o n i c s a n d D a t a P r o c e s s i n g F a c i li ti e s ", H u g h e s A s s o c i a te s , I n c . , 1 9 9 5 ]


45/63

Agent RetentionAgent Retention Allows for time to deal with persistentAllows for time to deal with persistent

ignition sources and for hot surfaces to coolignition sources and for hot surfaces to cooldown. Particularly important whendown. Particularly important when

automatic shutdown is not part of activationautomatic shutdown is not part of activationsequence.sequence.

Common cause of discharge test failures.Common cause of discharge test failures.

No hard answer for how long is enoughNo hard answer for how long is enough(case by case).(case by case).


46/63

Agent RetentionAgent RetentionThe time, T, for the interface to descend to anyThe time, T, for the interface to descend to any

level, H, in the enclosure, is:level, H, in the enclosure, is:

T=2AT=2Aenclencl[(K[(K33HHenclencl))0.50.5--(K(K33H)H)0.50.5]/K]/K33FFAACCDDAALeakLeak

wherewhere

KK33=2g(p=2g(pmixmix--ppairair)/[p)/[pmixmix+p+pairair(F(FAA/(1.0/(1.0--FFAA))]))]


47/63

Agent RetentionAgent Retention

Agent retention or holding time usuallyAgent retention or holding time usually

based upon final interface height equal tobased upon final interface height equal to

highest (lowest for nitrogen) combustiblehighest (lowest for nitrogen) combustible

material in enclosure.material in enclosure.

Agent Retention Time in 10x10x10 ft Enclosure

with FA=0.5, Highest Combustible at 7.5 ft or


48/63

g

Lowest Combustible at 2.5 ft for Nitrogen

Leakage Area (ft2)

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00

AgentRetentionTime(minutes)

0

2

4

6

8

10

12

14

16

18

20 5% Halon 13018.7% FM-200

16.8% FE-13

11.7% FE-25

40.3% Inergen (IG-541)

54.6% Argon (IG-01)

45.5% Argonite (IG-55)

36.4% CO240.3% Nitrogen (IG-100)

Agent Retention Time in 10x10x10 ft Enclosure

with FA=0.5, Highest Combustible at 7.5 ft


49/63

Leakage Area (ft2

)

0.0 0.1 0.2 0.3 0.4 0.5

AgentReten

tionTime(minu

tes)

0

2

4

6

8

10

12

14

16

18

20

5% Halon 13018.7% FM-200

16.8% FE-13

11.7% FE-25

40.3% Inergen (IG-541)

54.6% Argon (IG-01)

45.5% Argonite (IG-55)

36.4% CO2

40.3% Nitrogen (IG-100)

Enclosure Pressure andEnclosure Pressure and


50/63


VentingVenting

The experienced enclosure pressureThe experienced enclosure pressure

depends upon the following factors:depends upon the following factors:

-- Total leakage area.Total leakage area.

-- Design concentration.Design concentration.

-- Rate of agent addition (discharge time).Rate of agent addition (discharge time).



51/63


VentingVenting For agents stored as a liquid, Halon 1301,For agents stored as a liquid, Halon 1301,

FMFM--200, FE200, FE--25, and FE25, and FE--13, the enclosure13, the enclosureundergoes two pressure pulses.undergoes two pressure pulses.

-- The first pulse is negative and is due to theThe first pulse is negative and is due to thequick reduction in enclosure temperaturequick reduction in enclosure temperaturecaused by the vaporization of the agent in thecaused by the vaporization of the agent in the

enclosure.enclosure.-- The second pulse is positive, caused by theThe second pulse is positive, caused by the

volume of the added agent.volume of the added agent.

8% FM-200TM

Discharge with 226 cm2

(35 in2) Leak in 85 m

3(3000 FT

3) Enclosure

Enclosure Pressures


52/63

8% FM-200 Discharge with 226 cm (35 in ) Leak in 85 m (3000 FT ) Enclosure

[Great Lakes Chemical Corporation, 1997]

CylinderActuation

NozzleLiquidRun-Out

TotalDischarge

Time (sec)

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Pre

ssure(iwc)

-1.50

-1.25

-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

Pre

ssure(Pa)

-350

-300

-250

-200

-150

-100

-500

50

100

150

200

250

300

350

400

450

Leakage Area per Enclosure Volume (in2/ft

3)

0.008 0.009 0.010 0.011 0.012 0.013 0.014 0.015


53/63

Enclosure Pressures During FM-200TM

Testing

[M. Robin, "Investigation of the Pressure Dynam ics of FM-200 System Discharges",Presented at 1997 Halon Options Technical W orking Conference, Albuquerque, NM, May 1997]

En

closurePressure

(iwc)

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

EnclosurePressure

(Pa)

-700

-600

-500

-400

-300

-200

-100

0

100

200

300

400

500

600

700

Leakage Area per Enclosure Volume (cm2/m

3)

1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3

7% Cinder Block

8% Cinder Block

9% Cinder Block

7% Gypsum

8% Gypsum

9% Gypsum



54/63


VentingVenting

For agents stored as a compressed vapor,For agents stored as a compressed vapor,

IGIG--01, IG01, IG--100, IG100, IG--55, IG55, IG--541, the541, the

enclosure undergoes a single pressure pulse.enclosure undergoes a single pressure pulse.

-- Maximum enclosure pressure corresponding toMaximum enclosure pressure corresponding tothe maximum rate of agent addition.the maximum rate of agent addition.

-- Easier to predict as the significance of the heatEasier to predict as the significance of the heat

transfer from the compartment boundaries istransfer from the compartment boundaries is

reduced.reduced.



55/63


VentingVenting With detailed flow predictions andWith detailed flow predictions and

enclosure details, the experienced enclosureenclosure details, the experienced enclosure

pressure can be predicted with anpressure can be predicted with an

appropriate equation of state.appropriate equation of state.

System Pressures


56/63

Time (sec)

0 20 40 60 80 100 120 140 160

Pressure(psig)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Exp-Manifold

Exp-Nozzle

Pred-Cylinder

Pred-Node1

Pred-Manifold

Pred-Nozzle

Enclosure Pressure


57/63

Time (sec)

0 10 20 30 40 50 60

Enclosur

ePressure(iwc

)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Measured

Predicted



58/63


VentingVenting Without detailed flow predictions, theWithout detailed flow predictions, the

enclosure pressure can be found from anenclosure pressure can be found from an

orifice equation and an assumptionorifice equation and an assumption

regarding the peak agent flow rate.regarding the peak agent flow rate. DPDPenclencl=[Q=[Qagent,maxagent,max/(CdA/(CdALeakLeak(2g/p(2g/pmixmixg)g)

0.50.5)])]22



59/63


VentingVenting Enclosure StrengthEnclosure Strength

-- Varies with type of construction, but is lessVaries with type of construction, but is less

than you might think. 2than you might think. 2 iwciwc (500 Pa) is a(500 Pa) is a

conservative value.conservative value.-- Venting is required if developed pressure isVenting is required if developed pressure is

greater than what can be tolerated.greater than what can be tolerated.


60/63

SummarySummary Extinguishing concentrations are determined byExtinguishing concentrations are determined by

test and are agent and fuel specific. Need totest and are agent and fuel specific. Need tounderstand how protected hazard relates to testunderstand how protected hazard relates to test

fuels.fuels.

2000 edition of NFPA 2001 includes an increased2000 edition of NFPA 2001 includes an increased

safety factor (30%) for Class B and manuallysafety factor (30%) for Class B and manually

activated systems.activated systems. ISO 14520 requires a 30% safety factor for ClassISO 14520 requires a 30% safety factor for Class

A and B hazards.A and B hazards.


61/63

SummarySummary For some systems/applications the minimumFor some systems/applications the minimum

safety factor may not be appropriate. Thesafety factor may not be appropriate. Thedesigner must understand and account for thedesigner must understand and account for theissues that affect system reliability.issues that affect system reliability.

NFPA 2001 allows halocarbon concentrationsNFPA 2001 allows halocarbon concentrationsabove the NOAEL if means are provided to limitabove the NOAEL if means are provided to limitthe exposure time to those determined using thethe exposure time to those determined using the

PBPK model.PBPK model. Software that has been thoroughly tested andSoftware that has been thoroughly tested and

validated is essential.validated is essential.


62/63

SummarySummary Early detection and fast suppression are the key toEarly detection and fast suppression are the key to

limiting production of thermal decompositionlimiting production of thermal decompositionproducts.products.

Agent retention time is dependent on agentAgent retention time is dependent on agent

concentration, total leakage area, and leakconcentration, total leakage area, and leakdistribution.distribution.

There is no hard answer for how long the retentionThere is no hard answer for how long the retention

time needs to be.time needs to be.


63/63

SummarySummary Developed enclosure pressures depend on theDeveloped enclosure pressures depend on the

agent, design concentration, leakage area, andagent, design concentration, leakage area, anddischarge time.discharge time.

Venting is required if the developed pressureVenting is required if the developed pressure

exceeds the enclosure strength.exceeds the enclosure strength.

clean agent system designs

Documents