P a rt 2: Determina tio of ex p losio in ic es of c ombu tible ga ses in air... It is imp orta nt to quire ga s/ air mix ture is ver ifie.
Trang 1d’a ir a utres que les m&a ges a ir/p u si& re et a ir/ga z
De criptors : e plo io p ro fin , d st, air , gas mixture , te ts, e plo io in ex
Pric bs d o 4 pa ge
Trang 2IS0 (h Interna tio a l O rga niza tio for Sta nda rdiza tio ) is a worldwid fe era tio of
na tio a l sta nda rds b dies (IS0 memb r b dies) T he work of pre a ring Interna tio a l
Sta nda rds is n rma lly ca rrie out throu h IS0 tec hnic a l com ite s Ea ch memb r
b dy intereste in a s bject for which a tec hnic a l com ite h s b e esta b lish d ha s
me ta l a d n n-gov ernme ta l, in laiso with ISO , a lso ta ke pa rt in th work
Dra ft Interna tio a l Sta nda rds a do te by th tec hnic a l com ite s a re c irc la te to
th memb r b dies for a pprov a l b fore th ir a cce ta nce a s Interna tio a l Sta nda rds by
th IS0 C ounc il They a re a pprov ed in a ccorda nce with IS0 proce ures re uiring a t
lea st 7 % a pprov a l by th memb r b dies voting
Interna tio a l Sta nda rd IS0 616 /3 wa s pre a re by Tech ic a l Com ite ISO /TC 21,
Equipme t for fire protectio a d fir e fighting
Users sh uld n te tha t al Interna tio a l Sta nda rds un ergo revisio from time to time
a nd tha t a ny refere ce ma e h rein to a y oth r Interna tio a l Sta nda rd imp lies its
la test e itio , unles oth rwise sta te
0 Interna tio a l O rga niza tio for Sta nda rdiza tio , 19 5 0
Printe in Switzerla nd
Trang 3Explosion p r otec tion systems -
0.1 The a sses me t of mea sures re uir ed to p rovid p rotec -
tio aga inst ex p losio ha za rds involving fuel/ air mix tures
re uires p r io r d termina tio of th p ote tia l ex p losio severity
of s c h mix tures, by th mea sureme t of ex p losio in ic es
sh uld b teste a ga inst ex plosio s of known severity
The severity of a fuel/ air ex p losio is a func tio of th folow-
ing :
a) th p hy sica l a nd c hemic a l p rop erties of th fuel
b ) th c once tra tio of th fuel in th fuel/ air mix ture;
c ) th h moge eity a nd turb ule c e of th fuel/ air mix -
ture ;
e) th ge metry of th c onta in r:
f th temp era ture, a nd p res ure of th fuel/ air mix ture
0.2 This p a rt of IS0 616 is o e of a series d a ling with ex -
p losio p rotec tio s stems The oth r p a rts a re a s folows:
Pa r t 1: Determina tio of ex p losio in ic es of c ombu tible
du ts in air
P a rt 2: Determina tio of ex p losio in ic es of c ombu tible
ga ses in air
Pa r t 4 : Determina tio of efic a c y of ex p losio s p res io
s stems
0.3 The interp reta tio of ex p losio in ic es d termin d by th
meth d sp ec ifie in this p a rt of IS0 618 a nd th ir relatio to
p losio ha za rds sh uld b recognize In p ar tic ula r , th d gre
of turb ule ce ca n influe c e th ha za rd signific a ntly In p ra c tic e,
th ln b twe n a given d gre of turb ule c e a nd a sp ec ific
typ of ha za rd is th r esp onsib ilty of sp ec ialists in th fields of
exp losio s a nd ex p losio p rotec tio
du tr ial p la nts a re :
a ) quiesc ent turb ule c e c on itio s p r evailng in stora ge
v es els ;
b ) high turb ule c e c on itio s p r evailng in th regio of a n
ex tra c tio fa n
It sh uld b rea lize tha t turbule c e ca n arise in two way :
op era ting c on itio s, a s a co se ue ce of p erturb a tio s to
th air-low;
b ) turb ule ce in u e by ob struc tio s within a n instal-
latio o a ga s which expa nds a s th res lt of a n ex p losio
This p art of IS0 616 sp ec ifies a meth d for th d termina tio
of th ex p losio in ic es of fuels in air (oth r tha n du t/ a ir a nd
ga s/ a ir mix tures) in a n e close spa ce F uel/ air mix tures ma y
b , for ex a mple, ga s/a ir/du t mixtures a nd va p orize lquid/ air
mix tures It giv es th cr ite r ia by which res lts ob ta in d u ing
oth r test proce ures ca n b c orela te to y ield exp losio in-
dices a s d termin d by th meth d sp ec ifie in this p a rt of
IS0 618
2 Field of ap p lic atio
This p art of IS0 618 is ap p lic a b le o ly to th d termina tio of
ex plosio in ic es p erta ining to th d v elo me t of c onta in d
fuel/ air exp losio s a fter ignitio of th rea c ta nts It d es n t
a pp ly to in ic es p ertaining to th c on itio s n ces a ry to ca use
ignitio of th rea c ta nts,
NOT E - Du t an gas/ air mix ture, bo th at c onc entr atio s b elow the
e x p lo ive ran e, c an form ex p lo ive mix ture wh n c omb in d Du t
whic h c an o t be c aus d to e x p lo e e e with a hig e er gy ig itio n
s ourc e may b ec ome ex p loiv if a flammab le gas o r vap our is ad e d,
1
Trang 43 D efinitio s
F or th purp se of this p a rt of IS0 616 th folowing d fini-
tio s a p p ly
3.1 ex p losio : Prop a ga tio of a flame in a p re-mix ture of
c omb ustib le ga ses, s sp n e du ts), c ombu tib le v a pourk),
mists), or mixtures th re f, in a ga se u oxida nt s ch a s air , in
a c lose or s b stantia lly close ves el
3.2 ex p losio In ex: Numeric a l term, d termin d in a c cord-
a nce with th test meth ds sp ec ifie in this p a rt of IS0 616 ,
which c ha ra c terizes th c onta in d ex plosio of a sp ec ifie c on-
c entra tio of rea c ta nts in a v es el ha v ing a v olume of 1 m3
NO T E - F ig r e 1 sh ws th pres ure ime c urve, expres e in ba rs1
a nd seco ds resp ec tively , of a ty p ic al ex p losio
3.2.1 ex p losio in ex p ,: Ma ximum overp res ure r elative to
th p res ure in th v es el a t th time of ignitio a tta in d during
a n ex p losio
3.2.2 ex p losio in ex p ,,
Ma ximum va lue of th ex p losio
in e p,, d termin d by tests ov er a wid ra nge of rea c ta nt
c onc entra tio s
rate of pres ure rise with time (dp ldt, of a n ex p losio in a
volume V, a cc ording to th e ua tio
x v ”3
NOT E - Un er c e r tain circ mstanc es, this e quatio n is no t valid fo r
vesels with a le ngth to diam eter ratio gre ater than 2 : 1 o r with a
volume o f le s than 1 m?
sio in e K d termin d by tests ov er a wid ra nge of rea c ta nt
c onc entra tio s The viole c e of a n ex p losio is ev a lua te from
th va lue of K, ,
3.3 turbule c e in e : Numerica l term which c ha ra c terizes
th d gre of turb ule c e in th ex p erime ta l c on itio s un er
which th ex p losio in ic es a re d termin d
3.3.1 turb ule c e in ex t (ignitio d la y ) : Ex p erime ta l
p ar am eter de fine d as the time inte r val betwe n th initiatio n o f
a fuel disp ersio proce ure in a n ex p erime ta l a p pa ra tu , a nd
th a c tivatio of th ignitio sourc e It c ha ra cterizes th d gre
of turb ule c e p revailng a t th mome t of ignitio
K ma x, turb ure t d termin d a s sp ec ifie in this p a rt of IS0 616 to
th ex plosio in e K,.,ax ,q iescent of th quies e t rea c ta nts It
is giv en by th e ua tio
K
T, =
max,tur bule t
K
ms , q ie c ent
NOT E - For f ue l/air mix ture , Kmax ,q iesc ent
is a th oretic ally d r i e
p ar am ete r
C
Ti e, t
F ig r e 1
I) 1 bar = 10 5 Pa
2
Trang 54 Test meth d
4 1 G ener al
The ex p erime ta l a p pa ra tu d sc rib ed in this p a rt of IS0 616
is ch se a s a n exa mple, a nd is s ita b le for th eva lua tio of
ex p losio in ic es of fuels mixe with air , If th fuel is a com-
b ustib le ga s or a comb ustib le du t, th test proc edures d -
sc rib ed in pa rts 1 a nd 2 resp ec tively of this Infer na tio al Sta n-
da rd sh uld b u e This p a rt of IS0 616 sp ec ifies th test
p roc edure for th ca ses wh re th fuel is a hy b rid (c omb ustib le
ga s p lu du t mix ture a nd gives recom e da tio s for th p ro-
ce ure for a c ombu tible mist (in drop lets of c omb ustib le
lquid) in air
NO T ES
1 Wh n th ga se u ox ida nt is n t air , b ut, for exa mple, a
nitroge /oxy ge mix ture of difere t c omp ositio , th test proc edures
d sc rib ed in this p a rt of IS0 618 ca n b a da pte by rea ding “ox ida nt
instea d of “air ”
2 Wh n th initial pres ure or temp era ture of th fue l/ air mix ture is
n t a mb ie t, a test proce ure sim iiar to th p roce ures d sc rib d in
this p a rt of IS0 618 ca n b u e
2 b a r This c onta in r is fite with a 19 m (3/ 4 in) quic k-
c onta in r within IO ms of op ening th va lv e The c onta in r is
(3/ 4 in) inter nal dia meter tub which is forme into a p er-
fora te (4 to 6 m h le dia meter) semic irc ula r spra y p ip e The
numb r of h les in th p ip e shall b ch se s ch tha t th ir total
c ros -sec tio a l a re is a p p roxim ely 3 0 m 2
The ignitio source c omprises two p yrotec hnic igniters with a
total e erg of 10 kJ a nd set to ignite a fter a fix ed ignitio n
d la y , turb ule c e in e t, = 0,6 s The total ma ss of th igni-
t& n sourc e is 2,4 g a nd co sists of 4 % zirc onium meta l,
3 % b a rium nitrate a nd 3 % b a rium p erox id It is ignite by
a n elec tr i fu e h a d The ignite r is loc a te a t th ge metric
c entre of th ex p losio cha mb er A p res ure tra nsdu er is fite
to mea sure ex p losio cha mb r p res ure, this b eing lne to a
rec ord r
4 3 P r oc ed r e
4 2 Ap p ar atu
The a ppa ra tu c onsists es e tially of a c y lin r ic al ex p losio
cha mb r with a v olume of 1 m3 a nd a n a sp ct r atio n minally of
1 : 1, a s sh wn in fig re 2
Prep a re th ga s/ a ir mix ture in th 1 m3 cha mb r b y, for ex -
a mp le, u ing th meth d of p ar tial p res ures It is imp orta nt to
quire ga s/ air mix ture is ver ifie
A c onta in r of a p p rox im ely 5 I c a p a c ify is a tta c he to th ex -
p losio cha mb r a nd is ca pa ble of b eing p res urize with air to
Pla c e th du t sa mp le, th ma ss of which shall b tha t re uire
to ob ta in th a p p rop ria te co c entra tio , in th 5 Ic onta in r a nd
p res urize it with air to 2 b a r Start th pres ure rec ord r a nd
/-
C onta in r
Pres ure tra nsdu er
C ombu tib le
spra y p ip e
F ig re 2
Trang 6th n a c tiva te th sa mple c onta in r va lv e folowe by th
ignite r
NOT E - Le ttin the c omp res d d s t/ air c har ge into the ex p lo io
c hamb er in uc es turb ule nc e in the gas/air mix ture Th influ nc e o f
the c ompre s d d s t/ air charge o n the final ex p lo ive r e actant c onc en-
tratio n s ho ld be take ’n into ac c ou t
R ep a t this proce ure for a wid ra nge of rea c ta nt co c entra -
tio s to ob tain c rv es of pm, in b a rs, a nd K, in b a r metres p r
seco d v ers s rea c ta nt c once tra tio , a s a p rce ta ge by
v olume [% (V/ VI to d termin pma x a nd Kma x resp ec tively
(se fig re 3)
NOT E - Th ig itio n d lay turb ule nc e in e t c ho e fo r th s e te ts
is the time interval ne e de d to disp er se all th d st in the ex p lo io
c hamb er tvc orr esp on s to a sp ec ific le el o f tur bule c e Tu an h nc e
has an influ nce o n the measur ed Kmax valu s Sinc e s me tur bule nce
a lways ex ists in a d st ssp enio , 7 ’, is n c es ariy gre ater than I
Fig r e 3
4 3.2 Mis t/air mix tur e tests
Sinc e, c ontra ry to du ts, th p ar tic le sizes of th mist ca n va ry
wid ly d p n ing o th situa tio in th p lant, th re is n sta n-
da rdize mea ns of esta b lishing th mist/ air mix ture
It is th refore n ces a ry to d termin b efore th tests wha t
drop let sizes wi oc ur in th p lant, a nd to selec t a test d v ice
tha t wi ‘c rea te th r i ht size of drop lets a nd th r i ht level of
turb ule c e Afer th mist/ air mix ture ha s b e esta b lish d,
ignitio of th mix ture is efec te in th ge metric ce tre of th
4 3.1I
4 3.3 D eter mination of ex p losion in ices
F or th d termina tio of th ex p losio in ic esp ,, ,a nd Kmx of
fue l/ air mix tures, tests sh uld b c arrie out ov er a wid ra nge
of rea c ta nt co c entra tio (se fig r e 3)
The ex p losio in ic es of fuel/ air mix tures ca n b d termin d
u ing a lterna tive test e uipme t a nd/or test proce ures p ro-
res lts ob ta in d u ing th 1 m3 a ppa ra tu for a large numb r of
fuels
The test meth ds d s rib ed in c la use 4 a llow th ex p losio
in ic es pmx a nd Kmx of fuel/ air mixtures to b d termin d It
ca n b sta te tha t, in ge era l, th a cc ra cy of a pma x d ter-
d p n e t o th c on itio s of turb ule c e of th mix ture a t th
time of ignitio
a ) typ of fuels(s);
b ) p ar tic le size distr ib utio ;
c ) c on itio s of turb ule c e (urb ule c e in ex );
d1 pmx, in ba rs;
in b a r metres p er seco d;
c la use 4; s ch d via tio s a re p ermis ib le, p rovid d th y are
r ep orte ex a c tly ;
h) in th ca se of m ist/ air mix tures, d ta ils of th mist
ge era ting d v ice;
j) da te of test