12 Pipe Sizing

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#!

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#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