Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 15835 (2009): Gaseous Fire Extinguishing Systems -HCFC-125 Extinguishing Systems [CED 22: Fire Fighting]

IS 15835 : 2009

Indian Standard

GASEOUS FIRE EXTINGUISHING SYSTEMS ­HCFC-125 EXTINGUISHING SYSTEMS

ICS 13.220.10

CD BIS 2009

BUREAU OF INDIAN STANDARDSMANAK BHAVAN . 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

February 2009 Price Group 5

Fire Fighting Sectional Committee, CED 22

FOREWORD

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by the Fire FightingSectional Committee had been approved by the Civil Engineering Division Council.

It is important that the fire protection of building or plant be considered as a whole. HCFC-125 total floodingsystems form only a part, though an important one, of the available facilities. However, it should not be assumedthat their adoption necessarily removes the need to consider supplementary measures, such as the provision ofportable fire extinguisher or mobile appliances for first aid or emergency use, or measures to deal with specialhazards.

HCFC-125 is recognized as effective for extinguishing Class A, Class B and Class C fires and also where electricalrisks are present. Nevertheless, it should not be forgotten in the planning of the comprehensive schemes thatthere may be hazards for which this technique is not suitable, or that, in certain circumstances or situation, theremay be danger in its use, requiring special precautions.

Advice on these matters can be obtained from organizations involved with the installation of HCFC-125 totalflooding systems. The design and fabrication of the container shall be in accordance with the requirements of theChief Controller of Explosives, Nagpur.

In the formulation of this standard, assistance has been derived from ISO 14520-8 : 2006 'Gaseous fire extinguishingsystems - Physical properties and system design - Part 8: HCFC -125 Extinguishing systems'.

For the purpose of deciding whether a particular requirement of this standard is complied with, the final valueobserved or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2 : 1960'Rules for rounding off numerical values (revised)'. The number of significant places retained in the rounded offvalue should be the same as that of specified value in this standard.

AMENDMENT NO. 1 MAY 2010 TO

IS 15835 : 2009 GASEOUS FIRE EXTINGUISHING SYSTEMS ― HCFC-125 EXTINGUISHING SYSTEMS

Substitute ‘HFC 125’ for ‘HCFC-125’ wherever appears in the standard.

(CED 22)

Reprography Unit, BIS, New Delhi, India

IS 15835 : 2009

Indian Standard

GASEOUS FIRE EXTINGUISHING SYSTEMS ­HCFC-125 EXTINGUISHING SYSTEMS

1 SCOPE

1.1 This standard sets out specific requ irements forthe design and installation of total flooding fireextinguishing systems employing HCFC-125 gasextinguishant . This standard is applicable to singlesupply as well as distributed supply systems.

1.2 This standard complements various generalrequirements applicable to all types of gaseousfire-extinguishing systems (Halocarbon as well as Inertgas systems) listed in IS 15493. As such, both thesestandards should be read together before designing asystem. Where requirements in both the standardsdiffer, this standard shall take precedence.

1.3 Th is standard covers total flooding systems ofHCFC-25 operating at nominal pressures of 2.5 MPaand 4.2 MPa only at 21°C.

2 REFERENCE

The standard listed below contains provision whichthrough reference in this text, constitutes provision ofthis standard. At the time of publication, the editionindicated was valid. All standards are subject torevision and parties to agreements based on thisstandard is encouraged to investigate the possibilityof applying the most recent edition of the standardindicated below:

by extensive experiments for several surface type firesparticularly those involving flammable liquid s andgases and polymeric materials. For deep- seated fires.longer soaking times may be necessary but are difficultto predict.

3.1.3 It is important that concentrations are not onlyachieved but also maintained for a sufficient period oftime to allow effective emergency action by trainedpersonnel. This is equally important in all classes offires since a persistent ignition source can lead to arecurrence of the initial event once the HCFC-125 hasdissipated.

4 GAS CHARACTERISTICS AND PROPERTIES

4.1 HCFC-125 is a colourless . electrically non­conductive gas with a density approximately four timesthat of air.

4.2 HCFC-125 total flooding systems can be used toextinguish all classes of fires. For Class C fires (firesinvolving gases) , the risk of explosion after extinctionshould be studied with care. Information on use andlimitations of HCFC-125 is available in IS 15493(see 1.2).

4.3 Chemical formula of HCFC-125 gas is shown inTable I.

Table I Composition or HCFC·I2S GasIS No.

15493 : 2004

TItle

Gaseous fire extinguishingsystems - General requirement

CleanAgent

Formula

Chemical Name CommercialName

3 GENERAL INFORMATION (1)

CHF,cF,

0) U)Penta fluoro ethane (99.85 percent) HCFC-125

3.1 Application

3.1.1 HCFC-125 total flooding system is designed todevelop a controlled atmosphere in an enclosed spaceand extinguishes the fires by physically cool ing thefuel and by breaking the free radical chain reactionand thereby interfering with the combustion proces s.The appropriate HCFC-125 concentration shall alsobe mainta ined unt il the temperature with in theenclosure has fallen below the re-ignit ion point.

3.1.2 The minimum HCFC-125 conc entr a t io nnecessary to extinguish a flame has been determined

4.4 HCFC-125 is a gas liquefied at suitable pressureand temperature that can be stored in a pressurizedcontainer.

4.5 HCFC-125 gas shall comply with specification asshown in Table 2.

4.6 Physical propert ies of HCFC- 125 gas is sho wn inTable 3.

4.7 Toxicological information for HCFC-125 gas isshown in Tables 4 and 5.

IS 15835 : 2009

Table 2 Specification for HCFC-I25 Gas(Clause 4.5)

51 No. Property Requlremen!

(I) (2) (3)

i) Purity 99 pett'.CR byrook: peRm. Minii) Moisture. percent by weight, 0.00 1, Ma x

Maxiii) Acidity ppm by weight 3.0

HCI equivalent, Maxiv) Non·volalile residue 0.05 percenl gi l00 ml, Max

Table 3 Physical Properties of HCFC·I25 Gas(Clause 4.6 )

sa No. Property V.lue

(I) (2) (3)

i) Molecular mass 120.02ii) Boiling poinl at 0.1 MPa, "C -48.5

iii) Freezing point, ·C -102.8iv) Vapour pressure al200C, MPa 1.21v) Speci fic volume of superheated vapour 0.259

at 0.1 MPa and 20·C (m'lkg)vi) Critical temperature, OC 66

vii) Critical pressure, MPa 3.395viii) Critical volume, ccJmol 2 10

ix) Critical density, kglm' 5nx) Liquid density al 20OC, kglm' I 218

xi) Saturated vapour density at 20oe, kglm' 76.92

Table 4 Toxicological Information forHCFC·I25 Gas

(Clause 4.7)

51 Property V.lurNo. Pennt

( I) (2) (3)

i) No observed adverse effect level (NOAE L) 7.5ii) Lowest observed adverse effect level (LOAEL) 10iii) Four hour lethal concenlrlllion Le,.. >70

Table 5 Time for Safe Human ExpoSUre" at StatedConcentration for HCFC·I25

(Clause 4.7)

sa No. IICfC·I25 CODcratratio. Hu .... Exposure nme

r Percenl VIVA

minppm"

( I ) (2) (3) (4)

i) 7.5 75 000 500ii) 8.0 80 000 5 00

iii) 8.5 85000 500iv) 9.0 90 000 SOOv) 95 95 000 5 00

vi) 10 0 100 000 500vii) 10 5 105000 500

viii) 11.0 110 000 5 00ix) 11.5 115 000 500x) 12.0 120 000 16 7

xi) 125 125000 059xii) 13.0 130 000 0.54xiii) 13.5 135 000 0.49

NaTE - Dataderived from EPA appro ved and peer -reviewedPBPK mode l or its equ ipment

2

4.8 Container Characteristics

The maximum fill density, container-working pressureof the HCFC·125 cylinders shall not exceed the valuesprovided in Table 6 for systems operating at 2.5 MPaand 4.2 MPa respectively.

Table 6 2.5 MPa and 4.2 MPa Storage ContainerCharacteristics for HCFC-125

SI No. Property V.lue,.---"---.,2.5 MPa 4.2 MPa

( I) (2) (3) (4)

i) Maximum fill dens ity, kg/m' 930 930ii) Maximum container work ing 4 5.3

pressure at 50·e, MPaiii) Super pressurization al 20·e, 2.5 4.2

MP~

NOTES

1 For further da ta on pressure/temperature relationship. Fig . Iand Fig . 2 should be referred.

2 Exceeding the maximum fill density may result in thecontai ner becoming ' liq uid full' . Wilh the result that anextremely high rise in pressure occurs wilh smal l inc reases intemperature that could adversely affect the integrity of thecontainer assembly.

4.9 Pressure venus Temperatures

To allow faster flow through piping systems, the naturalpressure ofHCFC-125 is often supplemented with drynitrogen. Commonly used pressures are respectively2.5 MPa and 4.2 MPa measured at 21°C. The respectivevapour pressures of HCFC-125 as well as dry nitrogenvary with temperat ure.

4.10 Nitrogen Super Pressurization

Nitrogen is soluble in HCFC-125. Thus when a storagecylinder is pressurized with nitrogen, some dissolvesin the liquid HCFC-125 and the rest remains in thevapour phase and combines with the vapour phase ofHCFC-125 to produce the pressure necessary to propelthe extinguishing agent HCFC-125 through thepipeline (see also Fig. I and Fig. 2).

5 SAFETY OF PERSONNEL

5.1 General

a) Any hazard to personnel created by thedischarge of HCFC-l25 shall be given duecons idera tion in the design of the system .Potential hazard can arise from the following:

I) the extinguishant itself;

2) the combustion products of the fire; and

3) breakdown products of the extingui shantresult ing from exposure to fire .

b) In areas. whe re there is a likelihood ofsignificant difference between gross and net

IS 15835 : 2009

8.0

7.0

6.0

5.0

4.0III0..:::E

3.0

2.0

1.0

J

/IJ~1v

vv V'

VI--I--

929 kglm3

897kwm3885kwm 3833kg1m3

eoo kglm3

0.0-20 -10 0 10 20 30 40 50 60 70 80 90

Temperature (·C)

FlO. 1 TEMPERATURE-PRESSURE CURVE FOR 2 .5 MPa AT 21°C

10080604020o

~

!II/~

II1/

L Vi--:~

2-20

4

8

6

12

14

10

Temperature (·C)

FIG. 2 T EM PERATURE-PRESSVRE C URVE FOR 4 .2 MPa AT 2 1° C

7 EXTINGUISHING AGENT SUPPLY

where

M =C =

V =S =

IS 15835 : 2009

volumes of the enclosure, utmost care shallbe exercized in proper system design to ensurethat maximum concentrations as detailed in7.1 are not exceeded .

I) Where design concentration exceeds theLOAEL. HCFC- I 25 shall be used fortotal flooding only in normally un­occupied areas. For minimum safetyrequirements, see 5 of IS 15493.

2) Toxicological information of HFC- I 25is shown in Table 4.

3) HCFC- I 25 system for spaces that arenormally occupied and designed toconcentrations above the NOAEL shallbe permitted, if means are provided tolimit exposure to the designconcentrations shown in Table 5 thatcorresponds to a maximum permittedhuman exposure time of 5 min.

5.2 MisceUaneous Hazards

Some of the additionai hazards are as below:

a) Cold Temperatures - Direct contact with thevapourizing liquid being discharged from aHCFC-125 nozzle will have a strong chillingeffect on objects and can cause frostbite burnsto the skin. The liqu id phase vapourizesrapidly when mixed with air and thus limitsthe hazard to immediate vicinity of thedischarge point. .

b) Visibility - Discharge of HCFC-125 maycreate a light mist resulting from condensationof m.oisturein the air. However, the mist rarelypersistsafter the discharge is completed. Thuslittle hazard is created from the standpoint ofreduced visibility. Once HCFC-125 isdischarged into an enclosure, its presence iseasy to detect through the normal senses inconcentrations above about 3 percent.

c) Uneven Distribution - In total floodingsystems, the high density of HCFC-125vapour requires the use of discharge nozzlesthat will achieve a well-mixed atmosphere inorder to prevent local pockets of higherconcentration . HCFC-125 and HCFC-125 airmixtures are also denser than air and will drift~d accumulate in low spaces, such as cellars,Pits and floor voids, and may be difficult toventilate effectively.

6 VENTING ARRANGEMENT

yenting shall be provided at levels as high as possibleIn the enclosure. Strength and allowable pressures foraverage enclosures shall be in conformity with the

4

following guidelines. The building requirements forthe type of enclosure and free venting requ ired canalso be calculated from the relevant specifications.

7.1 Quantity

a) Quantity Requirements (Main) - The amountof the HCFC-125 in the system shall be atleast sufficient for the largest single hazardprotected or group ofcommunicating hazardsthat are to be protected simultaneously.

b) Quantity Requirements (Reserve) - Samequantity as that of main quantity requirementsshould be available as reserve . However, ifthe replenishing of agent supply takes morethan 7 days at the site of installation, advicemay be sought from the authority concernedon quantity to be kept available as reserve.

c) Uninterrupted Protection - Reserve supplywhere provided and main supply should bepermanently connected to the distributionpiping and arranged for easy change-over toenable uninterrupted protection.

d) The quantity of the HCFC-125 required shallbe further adjusted to compensate for anyspecial conditions, such as unclosableopenings, forced ventilation, the free volumeof air receivers that may discharge into therisk, altitude (substantially above or below sealevel) or any other causes for the extinguishantloss. However in no case the designconcentration of HCFC-125 shall exceed itsLOAEL (see Tables 4 and 5)

7.2 Total Flooding Quantity

a) The amount ofHCFC-125 required to achievethe design concentration shall be calculatedfrom the following equations and this figureshall need further adjustment as statedin 7.1(d).

M= VCS(IOO-C)

total flooding quantity, in kg;

design concentration in percent byvolume; .

net volume of the hazard. tin m3;

KI + K2(n , where K. and Kz areconstants specific to the agent usedand T is minimum temperature insideenclosure;

K, = 0.1 825; and

K2 = 0.000 7

It may a lso be noted that this equationprovides an allowance for the normal leakagefrom a tight enclosure to accomplishequ alization of pressure .

b) Th e agent requirement per uni t volume ofprotected space can also be calculated by usingTabl e 8 for var ious levels of concentrationcorresponding to the temperature within theprotected enclosure . (F lood ing Fa ctorobta ined from Table 7 that is temperature ofthe enc losure versus gas concentration ,multiplied by net volume of the enclosure).

NOTE- Quantity of the agent shall be the highestof the valuescalculated from the provisions contained in 7.2(a)and 7.2(b).

7.3 The actual quantity of HCFC-125 gas storagerequ ired shall be determined in the following manner.which shall further be subject to changes for pressuredue to elevation [see 8(f) and Table 8).

7.3.1 Enclosure Volumes

The net enclosure volumes are calculated using thefollowing equations:

IS 15835 : 2009

a) ~/ = ~/. - V.'

h ) ~ / = V.....- V"

where

V,-\u = max imum net volume of theencl osure. in m\

= gross volume of enclosure, in m' :

= vo lume of the struc tura l/s imil arpermanent objects in the enclosurethat gas can not permeate, in 013;

VM>. = minimum net volume of enclosureconsidering the maximum anticipatedvolume of the occupancy related to theobjects in the enclosure, in 013; and

Vo = volume of the occupancy relatedobjects in the enclosure that gas cannot permeate for example, furniturefittings etc, in 013;

(This value shall be ignored if thevolume is less than 2S percent of themax imum net volume VNu ) .

8 DESIGN CONCENTRAnON

a) Determination of design concentration ofHCFC-12S shall include consideration of the

Table 7 Total Quantity (HCFC·l25)(Clause 7.2)

SI Temper- Sp«ific Vapour IICFC-I~ Mala lUqulrclDcats per UaUVoI...e orProtectrd SpKc Oa qt_')No. alurc Volumc DcsIp Cooc:utradoa by Vola_

r s c- - -·C m11kg 7 8 9 10 II 12 13 14 IS 16percent percent percent percent percent percent percent percent percent pcn:cnt

i) ·35 0.157 0.478 0.5S3 0.629 0.706 0.786 0.867 0.9S0 1.03S 1.122 1211ii) ·30 0.160 0.468 0.540 0.615 0691 0.768 0848 0.929 1.012 1.097 1.184iii) ·25 0.164 0.457 0.518 0.601 0675 0.751 0.829 0.908 0.989 Lon I.IS7iv) -20 0.168 0.447 0.517 O.S88 0.660 0.734 0.810 0.888 0.967 1.049 1.132v) · 15 0.171 0.437 0.505 0.575 0.646 0.719 0.793 0.869 0.947 1.026 1.101vi) -10 0.175 0.428 0.495 0.563 0.633 0.704 0.777 0.8SI 0.927 I.OM LOISvii) -5 0.179 0.420 0.485 0.552 0.620 0.690 0.761 0.834 0.901 0.91S 1.063viii) 0 0.182 0.411 0.475 0.S41 0.607 0.676 0.746 0.817 0.890 0.96S 1.042ix) 5 0.186 0.403 0.466 O.SJO O.S96 0663 0.731 0.801 0.873 0.946 1.021x) 10 0.190 0.396 0.457 0.S20 0.584 0.6S0 0.717 0.786 0.156 0.928 UI02xi) 15 0.193 0.389 0.449 O.SII OS74 0.638 0.704 0.7n 0.841 0.912 0.984xii) 20 0.197 0.381 0.441 O.SOI 0.563 0.627 0.691 0.7S1 0.12S 0.195 0966"iii) 25 0.200 0.375 0.433 0.492 0.553 0.61S 0.679 0.744 0.111 0.179 0.949xiv) 30 0204 0.368 0.425 0.484 O.S« o60S 0.667 0.731 0.797 0.864 0.932xv) 3S 0.207 0.362 0.418 0.475 O.S34 0594 0.656 0.719 0.7&3 0.849 0.916xvi) 40 0.211 0.356 0.411 0.468 0525 O.S84 O.64S 0.707 0.770 O.&3S 0.901xvii) 45 0.214 0.350 0.404 0.460 0.S17 0.S75 0.634 0.695 0.7S7 0.821 0.186xviii) 50 0.218 0.344 0.398 0.452 0.501 0.56S 0.624 0.684 0.74S 0.801 un,0,,) 55 0.221 0.339 0.391 0.445 0.500 0.S57 0.614 0.673 0.733 0.79S 0158xx) 60 0.225 0.333 0.38S 0.431 0.493 0.S48 0.6OS 0.662 0.722 0.782 O.84Sxxi) 65 0.228 0.328 0.379 0432 0.485 0.540 0.59S 06S2 0.711 0.771 0.832xxii) 70 0.232 0.323 0.374 0.425 0.478 0.531 O.S86 0.643 0.700 0.7S9 0.119xxiii) 75 0.235 0.319 0.368 0.419 0.471 0.524 0.S'8 0633 0.690 0.748 0807xxiv) 80 0.239 0.314 0.363 0.413 0.464 0.S16 O.S69 0624 0.680 0.737 0.796xxv) 8S 0.242 0.310 0.358 0.407 0.457 OS09 0.S61 061S 0.670 0726 0.784xxvi) 90 0.246 0.305 0.353 0.401 0.4SI 0.501 0.SS3 0.606 0.660 0.716 0.773xxvii) 9S 0249 0.301 0.348 0.395 0444 0.494 O.S4S O.S98 0.6S1 0.706 0.762

5

IS 15835 : 2009

type and quantity of combustibles involved,the conditions under which it normally existsin the enclosure, and any special conditionsin the enclosure. The HCFC-125 systemdesign shall be capable of establishinguniform design concentration throughout theprotected volume.

b) The distribution system for applying HCFC­125 to enclosed hazards shall be designedwith due consideration of the materialsinvolved, the type of burning expected andthe nature of the enclosure, anyone of whichmay affect the discharge times and rates ofapplication.

c) The minimum design concentration ofHCFC­125 for fires involving surface Class A fuels,and also fires involving flammable liquids andgases shall be as follows:

I) The minimum design concentration ofthe HCFC-125 agent for Class A surfacefire hazards shall be the extinguishingconcentration (6.6) for such fuels plus a20 percent safety factor (that is 8percent).

2) The minimum design concentration ofthe HCFC-125 agent for Class B fuelhazards shall be the Heptane cup burnerextinguishing concentration (8.6 percent)plus 30 percent safety factor (that is 11.3percent).

3) The minimum design concentration ofthe HCFC-125 agent for Class C,electricaVelectronic hazards shall be theextinguishing concentration for Class Asurface rues (6.6) plus 20 percent safetyfactor as stated in 8(c) (I).

NOTE - When: diffen:nt classes of hazards exist,desip concentration shall be for the hazard requiringtile gn:.rcst concentration.

d) Requirtnuntsfor FlameExtinguishments­For Class 8 fuels other than Heptane. testsshall be conducted in independentrecognized laboratories for the determinationof extinguishing concentration. This valueas determined shall be loaded by a safetyfactor of 30 percent. In no case. shall thedesign concentration be less than theextinguishing concentration plus a loadingfactor of 20 percent that is 8 percent or suchhigher figure. determined by test as indicatedabove .

Nom - When: a range of fuels an: jnSent, design~n shaIIbefor tile fuel teqUiringthehighestCOlICCIIUabOn • detcrmiDed in iDdependeut recognizedllbol'ldories.

6

e) Lastly, it is required to adjust the number ofHCFC-125 agent containers, where necessary,by compensating for ambient pressure changedue to location elevation as per Table 8 andround off the number as before. The equationin such cases will be as follows :

I) N, = N. atmospheric correction factor

2) N, = adjusted number of containers

3) N = initial number of containers

f) Atmospheric CorrectionFactors-Itshall benecessary to adjust the actual HCFC-125agent quantity for altitude effects. Dependingupon the altitude, atmospheric correctionfactor shall be applied as per the Table 8. Theadjusted HCFC-125 agent quantity isdetermined by multiplying the number ofHCFC-125 containers by the ratio of averageambient enclosure pressure to standard sealevel pressure.

Table 8 Atmospheric Correction Factors

SINo. Equivalcnt Enclosure AtmospbcricA1titudc Pressure Cerreenon Factor

m mmHg

(I) (2) (3) (4)

i) -920 840 l.Iiii) -610 812 1.07iii) -300 787 1.04iv) 0 760 1.00v) 300 733 0.96vi) 610 70S 0.93vii) 920 678 0.89viii) 1220 6S0 0.86ix) I S20 622 0.82x) 1830 S96 0.78xi) 2130 570 0.7Sxii) 2440 SSO 0.72xiii) 2740 528 0.69xiv) 3050 SOS 0.66

9 POST DISCHARGE SCENARIO

The HCFC-125 system shall be, when tested fordischarge test, in accordance with the followingrequirements:

a) Within I min of commencement of discharge.the concentrations at not more than I m abovethe floor of the enclosure or at the top of thehighest hazard shall not vary from the designconcentration by more than I percent byvolume.

b) At 10 min of the discharge or other period(as required if necessary). the concentrationsat the levels given in item (a) shall be notless than 80 percent of the designconcentration.

10 APPLICATION RATE, DURATION OFDISCHARGE AND DISCHARGE TIME

10.1 Design Application Rate

The design application rate shall be based on thequantity of HCFC-125 as per 7.2(a) and the durationof discharge required under 9(b).

10.2 Duration of HCFC-125 Discharge

The minimum theoretical injected concentration shallbe achieved within IO s and the actual injectedconcentration (that is the above plus a suitable safetyfactor adjusted for container rounding oft) shall beachieved within 2 min.

10.3 Discharge Time for the HCFC-I25 Gas

The discharge time shall be the time for actuation ofthe first HCFC·125 container valve to the achievementof the required design concentration or the dischargetime is the interval from the first appearance of liquidat the nozzle to the time when the discharge becomespredominantly gaseous. recognized by a change inthe appearance and sound of the discharge. Although,a discharge time of 10 s is considered adequate tonormal surface burning fires. where the fire mayspread faster than normal, or where high volumes orvital machinery or equipment are involved. higherrates shall be used .

a) The discharge time period is defined as thetime required to discharge from the nozzles90 percent of the agent mass at 21°C,necessary to achieve the minimum designconcentration based on a 20 percent safetyfactor for flame extinguishment.

b) The discharge time required to achieve90 percent of the minimum design concentrationfor flame extinguishment basedon a 20 percentsafety factor shall not exceed lOs.

c) Flow calculations performed inaccordance with13. or in accordance with the listed pre­engineered systems, shall beusedto demonstratethe discharge time requirements stated above.

d) When an extended discharge is desired tomaintain the design concentration for thespecified period of time, additional quantitiesof agent can be applied at a reduced rate. Theinitial discharge shall be completed within thelimits as specified above. Performance of theextended discharge shall be demonstrated bytest.

11 STORAGE CONTAINERS

The HCFC-125 storage containers shall comply withthe following in addition to various requirementscontained in IS 15493:

7

IS 15835 : 1009

a) The containers used in HCFC-125 systemsshall be seamless cylinders designed,fabricated. inspected. certified and stampedin accordance with the requirements of ChiefController of Explosives, Nagpur.

b) The design pressure shall be suitable forthe maximum pressure developed at 65°Cor at the maximum controlled temperaturelimit.

c) The containers shalI be charged to a fillingratio (fill density) not greater than 930 kg/m l

(0.93 kg/litre) and not less than 480 kg/m'(0.48 kg/litre).

d) The containers shall be super-pressurized withnitrogen (moisture content not greater than0.005 percent by volume) to a total pressureofeither 2.5 MPa :t 5 pereent or at 4.2 MPa i:

5 percent measured at 21 i: 1°C.

e) The storage containers shall have reliablemeans of indicating their pressure.

f) The storage containers shall have reliablemeans of indicating the variation ofcontainerpressure with temperature . A pressure/temperature chart (su Fig . I and 2) attachedto the container. is acceptable.

g) The requirements of authorities havingjurisdiction for containers may takeprecedence over the requirements of thisstandard. if their specifications are morestringent.

12 DISTRIBUTION SYSTEM

The HCFC-125 distribution system shall comply withthe folIowing in addition to various requirementscontained in IS 15493 .

12.1 Piping Network

a) The piping shall withstand the maximumexpected pressure at the maximum storagetemperature. as follows:

I) 2.5 MPa systems - 4.19 MPa at 55°C;and

2) 4.2 MPa systems - 6.58 MPa at 55°C.

b) Carbon steel pipes and fittings shall begalvanized inside and outside or otherwisesuitably protected against corrosion. Stainlesssteel pipes and fittings may be used withoutcorrosion protection.

c) The piping shall withstand the maximumdeveloped pressure at 55°C and shall be inaccordance with IS 15493 .

NOTE - Slaink$J SIceI pipes maybe ued ill altllpplicationssubject to appropriate designsll'ellJlh calculations.

SI No. Nomillal Mi.imum Muimum flow Rate forBon flow EquinleDt LeDgths of Pipe 0Ratt:mm kgls kgls

A.....r

Morc: Between Up 10

than 5 and 5m10m 10m

(t) (2) (3) (4) (5) (6)

i) 10 0.3 0.3 0.4 0.5ii) 15 0.5 0.5 0.7 1.0iii) 20 1.0 1.0 1.0 2.0iv) 25 1.5 I.S 2.7 4.0v) 32 2.6 3.5 5.6 8.0 g)vi) 40 3.8 4.5 8.6 12.2vii) 50 5.9 8.8 16.3 23.5viii) 65 8.8 14.5 25.4 37.0ix) 80 15.0 25.0 45.0 63.5x) 100 26.3 50.0 90.0 131.5xi) 125 43.0 95.0 172.0 250.0xii) ISO 57.S ISO.O 272.0' 408.0

h)

12.4 Nozzle Placementj)

a) The type of nozzles selected. their number andplacement shall be such that the designconcentration will be established in all partsof the protected enclosure and such that the k)discharge will not unduly splash flammableliquids or create dust clouds that could extendthe fire, create an explosion, or otherwiseadversely affect the contents or the integrityof the enclosure.

b) Selecting the number of nozzles in a systemshall take into acc ount, the shape of theenclosure (Area and volume), shape of thevoid (Raised flo or . suspended ceil ing),installed equipment in the enclosure/void m)(Chimney effect), allowed pressure at therestrictor (Pipe quality) and ob structions,

8

IS 15835 : 2009

12.2 Piping Fittings

a) Pipe fittings shall comply with therequirements given in IS 15493.

b) Fittings shall be selected according to the wallthickness or schedule number of the pipe towhich they are intended to be fitted .

12.3 Pipe Sizing

Pipe sizing is a complex issue, particularly in view ofthe two-phase flow within the pipe lines. Too small abore results in excessive pressure losses while too largea bore reduces the liquid flow velocity. This also mayresult in excess pressure drops and lower flow rates.Table 9 may be used as a guide to estimate pipe sizes .The sizes can bechecked using an approved computerflow calculation programme.

Table 9 Pipe Sizes versus Flow Rate (Informative)

which may affect the distribution of thedischarged agent and architecturalconsiderations.

c) Nozzles shall be selected and located toprotect an area less than its area of coverage.The area of coverage to the type of nozzleshall be so listed for the purpose.

d) In hazards having suspended ceiling.consideration shall be given for havingnozzles installed in the ceiling void(simultaneous discharge) in order to equalizethe pressure during discharge. thus reducingthe risk ofunnecessary damaging ceiling tilesetc.

e) In hazards having raised floor (not gas tight)consideration shall be given for hav ingnozzles installed in the floor void(simultaneous discharge) in order to equalizethe pressure and obtain extinguishingconcentration below the floor.

In hazards having suspended ceiling. nozzlesfor protecting rooms shall be installed in sucha way that the jets from the nozzles do notdamage the ceiling plates excessively duringdischarge. that is the nozzles to be positionedvertically with the discharge holes free of theceiling tiles and/or escutcheon plates. For lightweight ceiling tiles. it may be recommendedto securely anchor tiles for a minimumof 1.5 m from each discharge nozzle.

Maximum nozzle height above floor level fora single row ofnozzles is 4.1 m. Where ceilingheight (of the protected enclosure) exceed4.1 m, an additional row of nozzles shall beprovided for uniform and faster distributionof the agent within the enclosure.

Minimum nozzle height above the floor levelof the hazard shall be 46 m.

The maximum distance between nozzlesshould not exceed 6 m and the maximumdistance to walVpartition should not exceed3m.

In case of enclosures having no false ceiling.nozzles can be located on the ceilinganywhere within 0.5 m to 5 m from the wallsIn case of enclosures having false ceilings,deflector shields shall be used with eachnozzle and also nozzles shall be so located(with an anticipation ofdislodgement of falseceiling materials c: any movable o~jects inthe path of discharge) to prevent any damagethereto.

Nozzles shall be prov ided in all the concealedspaces, floor voids. ceiling voids etc besidesthe main area within the protected enclosure.

13 HYDRAULICS OF THE SYSTEM

13.1 General

a) An approved hydraulic calculation methodshall be employed to predict pipe sizes, nozzlepressure, agent flow rate, discharge per nozzleand the discharge time .

b) The various parameters as stated below shallbe considered to determine the followingminimum limits of accuracy:

I) The weight of agent predicted by flowcalculation to discharge from the nozzleshould agree with the total weight ofagent actually discharged from eachnozzle in the system within a range of-5 percent to + I0 percent of actualprediction.

2) The discharge time predicted by the flowcalculation method should agree with theactual discharge time from each nozzlein the system.

3) The accuracy of the calculated nozzlepressures versus actual pressures at eachnozzle should be such that actual nozzlepressures in an installation will not falloutside the range required for acceptablenozzle performance.

4) The nozzle pressure should not fall belowthe minimum or above the maximumnozzle pressure required for the nozzleto uniformly distribute the agentthroughout the volume which thatnozzle's discharge is to protect.

9

IS 15835 : 2009

13.2 Two-Phase Flow of HCFC·llS

See Annex E of IS 1549~ .

13.3 Engineered and Pre-engineered Systems

a) General - HCFC-125 is suitable for use inboth engineered (central storage) systems andpre-engineered (modular or packaged)systems, as described in 13.3(b) and 13.3(c) .

b) Engineered - An engineered system useslarge storage containers installed in a centrallocation. The containers are manifold togetherand a single pipe feeds the nozzle locatedinside the hazard area. Predicting pipepressure losses and designing nozzle orificesizes requires complex flow calculations forboth HCFC-125 and nitrogen phases, whichtakes into account the minimum andmaximum volumes or the enclosure.

c) Pre-engineered - A pre-engineered systeminvolves a single container with a maximumof two nozzles and a small piping network.This system can be multiplied to cover largervolume areas. The larger area is viewed as anumber of smaller areas each protected by asingle modular unit.

14 COMMISSIONING AND ACCEPTANCETESTING

14.1 Criteria for Acceptance

The completed HCFC-125 total flooding system shallbe commissioned in accordance with 9 of IS 15493and the system's performance proved.

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian ' Standards Act, 1986 to promoteharmonious development of the activities of standardization. marking and quality certification of goodsand attending to connected matters in the country.

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Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of'BIS Catalogue' and 'Standards: Monthly Additions'.

This Indian Standard has been developed from Doc: No. CED 22 (7307).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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