12. PIPE SIZING AND SPRINKLERS ARRAY DESIGN12.1 GENERAL
REQUIREMENTS12.1.1 SUPPLYMAINS:Thenominal
sizeofsupplytrunkmainsandbranch mains shall be not less than the
size of any installationmaindistributionpipe, at its
maininstallationcontrol valve,supplied by the trunk main.12.1.2
INSTALLATIONPIPEWORK:Individual sprinklersshall
notbeconnecteddirectlytodistributionandmaindistributionpipes,exceptinthecaseoflight-hazardinstallationswheresprinklermay
be connected directly to pipes not exceeding 5mmnominal bore.12.1.3
In ordinary or high-hazard installations arm pipes or drop
pipesnotexceeding!"mmnominal boreshall beusedtoconnectindividual
sprinklers where these are fed from pipes larger than#5mm nominal
bore,12.1.4 $here upright orpendent conventional orspray
sprinklersare%tted within &mmof thepipe axis alongside a pipe
ofnominal size greater than #5mm, the de'ector shall be not
morethan the appropriate distance given in Table (& above the
loweredge of the pipe.12.2 ORIFICE PLATES)12.2.1 *n ori%ce plate
used to hydraulically balance an installation, orto accommodate
pump characteristic, shall)a+ have an ori%ce diameter not less than
one-half of the internaldiameter of the pipe into which it is
%tted,b+ be %tted only in pipes of 5 mm nominal bore or greater,c+
be of brass or stainless steel with a plain central hole
withoutburrs, and of a thickness complying with Table (5,d+
haveanidenti%cationtag, pro-ectingbeyondany'angesbetween which it
is clamped, on which is clearly stamped thenominal
pipediameterandtheori%ce./.factor. 0alsoseerule (!.#+12.2.2 The
ori%ce plate shallbe %tted not less than two pipe internaldiameters
downstream of the outlet from any elbow or bend.12.2.3 The
relationship between ori%ce size, 'ow rate and the pressureloss
shall be calculated using the data given in Tables !( and !".1TABLE
1 14Loc!"o# o$ %&'"#()*'% )o#+%",* $**, &"&*% )'+*' !-#
./ 00 #o0"#) %"1*M"#"020-o'"1o#!
),"%!
#c* $'o0&"&* c*#!'* )"#* !o !-*%&'"#()*' c*#!'*
)"#*3004M5"020 -*"+-! o$ %&'"#()*' ,*6*c!o' 7o8* )o9*' *,+* o$
&"&*3004Co#8*#!"o#)%&'"#()*'
"#%!))*,2&'"+-!S&': %&'"#()*' 2&'"+-!;&*#,*#!
#,co#8*#!"o#) %&'"#()*'&*#,*#!10c+I.74 @YDRAULICALLY MOST
FADOURABLE LOCATION:The following shall be considered.TERMINAL SPUR
AND LOOPED DISTRIBUTION PIPEINSTALLATIONS WIT@ SPUR RANGES:In
thehydraulically most favourable location the shape of the
*5*9shall be as near as possible s0c+I.2324252612.. INTERMEDIATE
LEDEL INARACK SPRINKLERS12...1 $here more than 5 intermediate level
sprinklers are installedin the racks, roof and6or ceiling
sprinklers in the concerned areaalongwiththeintermediatelevel
sprinklersshall beinstalledwith a separate installation control
valve set.12...2 ;or hydraulic calculation purpose, it shall be
assumed thatminimumof
threesprinklersareoperatingsimultaneouslyoneach level up to a
maximum of three levels at the hydraulicallyremote position. The
minimum operating pressure in anysprinkler shall not be less than "
bars.12...3 In-rack sprinklers in association with the ceiling
sprinklers shallalways be fully calculated for the purpose of
hydraulics.J J J J J J J J J JJ27
