Fixed Foam calculation Share
The main purpose of this calculation is to find the amount of foam required, the size of the foam tank, the number and location of monitors, the capacity of the foam liquid pump and the fire pump. Contents
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1 Exa Exampl mplee
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1.1 Dimensions Dimension s of the protected area
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1.2 Foam solution supply suppl y rate
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1.3 Foam liquid amount and tank size
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1. Foam monitor capacity
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1.! Distance "et#een monitors
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1.$ %um"er of monitor monitorss
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1.& Foam liquid pump
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1.' (inimum capacity of fire pump
2 )efe )eferenc rences es
Example An example of a 4,!!! tonnes dead"ei#ht $hemical tanker is taken. For an oil tanker the rule requirement is the S%&AS $hapter ''(), *e#ulation +!,+. +!,+. 'n case of a chemical tanker, the rule reference is the'-$ the'-$ $ode $hapter . .
Dimensions of the protected area ere "e ha/e to find the area from the three options mentioned in the rules.
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.0 $ar#o tank deck area 1A0 defined as the product of the maximum breadth of the ship and the total lon#itudinal extent of the car#o tank spaces. ere breadth 1-0 2 3).)! m, len#th 1&0 2 3 m
Area A 2 - x & 2 4).) sq.m
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)0 Area of the lar#est sin#le tank A) is defined as t he product of breadth 1-)0 and len#th 1&)0. ere -) 2 +.! m, len#th 1&)0 2 ).)! m
Area A) 2 -) x &) 2 34.3) sq.m
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30 The third area concerns the co/era#e of the monitors, "hich "ill be done after the monitor location and number is decided.
Foam solution supply rate From the rules1'-$ .3.50, the rate of supply of foam solution shall not be less than the #reatest of the follo"in#6
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.0 7 2 ) lit8min8sq.m x A 2 ) x 4).) 2 43+.4 lit8min
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.)0 7) 2 )! lit8min8sq.m x A) 2 )! x 34.3) 2 +)+.4 lit8min
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.30 73 2 ! lit8min8sq.m x A3 2 ! x 9.)4 2 9).4 lit8min. ere the A3 is from the monitor calculation.
The lar#est fi#ure amon# the three is taken. ie. supply rate 7 2 43+.4 lit8min :ote6 For oil tanker desi#n foam calculation 1S%&AS $hapter ''(), *e#ulation +1300, the foam quantity is much less for the same tank dimensions. 'nstead of ), )! and ! lit8min8sq.m for a chemical carrier, it is !.+, + and 3 lit8min8sq.m; a factor of 3.3 times.
Foam liquid amount and tank size Accordin# to the rules, '-$ .3.+ , sufficient foam concentrate shall be supplied to ensure atleast 3! min of foam #eneration. For %il 8 m> is 3 ?. For a time T of 3! min operation and mixin# ratio, m, 3 ?, the foam liquid required "ould be F 2 1 7 x m x T0 8 !! 2 59). lit This is the minimum quantity of foam concentrate required in the foam tank. Accordin#ly the size of the tank is chosen. 'n this case an 5!! lit tank is chosen.
Foam monitor capacity From the rules, '-$ .3., atleast 5!? 17 min0 of the foam supply rate as per lar#est required rate 170 shall be deli/ered from each monitor.
7min 2 7 x !.5 2 43+.4 x !.5 2 4).) lit8min ere the type of monitor used is F:(@&(5!. The inlet desi#n pressure at the monitor 1after the loss of head from the Fire B.S pump dischar#e0 is + bar. 'ts capacity 1 7m0 is !! lit8min and the thro "in# len#th *o in still air is ! m. The rules, '-$ .3., states that the distance from the monitor to the farthest extremity of the protected area for"ard of that monitor shall not be more than 5? of the monitor thro" in still air conditions. ie. * 2 *o x !.5 2 ! x !.5 2 5).5 m
Distance between monitors Accordin# to the rules, '-$ .3.5, the capacity of any monitor shall be atleast ! lit8min8sq.m of the deck area protected by that monitor, such area bein# entirely for"ard of the monitor. Also one monitor to be pro/ided on each side of the front of the poop or ca#o tank decks 1refer '-$ .3.90. These front monitors should co/er an area "hose len#ht is < 1"hich is also the distance to next for"ard monitor0 and breadth the half( breadth -8). ie. -8) 2 3).) 8 ) 2 +. m. <a 2 7m 8 1! x -8)0 2 !! 8 1! x +.0 2 4.4 m For the other monitors, the co/era#e len#th is <) 1"hich is the distance to the next for"ard monitor0 and breadth -. <)a 2 7m 8 1! x -0 2 !! 8 1! x 3).)0 2 )4.) m Also the distance bet"een monitors can be calculated accordin# to the thro" len#ht *. For the front monitors the thro" len#ht is the hypotenuse, the quarter(breadth 1-840 one side and "e can find the distance to the next monitor. * 2 5).5 m *C) 2 1<b0C) D 1-840C). ie. <b 2 sqr.root *C) ( 1-840C) . ie. <b 2 5. m For the other monitors, the distance to the next for"ard monitor is <)a "hich is one side of the ri#ht an#le trian#le "ith t he hypotenuse as the thro" len#ht 1*0 and other side as half(breadth 1-8)0 <)b 2 sqr.root *C) ( 1 -8)0C) 2 sqr.root 5).5C) ( +.C)0. ie. <)b 2 49.9 m For < use the smaller /alue of <a and <b. Therefore < 2 4.4 m and <) use the smaller /alue of <)a and <)b. Therefore <) 2 )4.) m. Area co/ered A3 2 )4.) x 3).) 2 9.)4 sq.m. $onfirm if the obtained /alue satisfies the abo/e conditions.
Number of monitors :umber of monitors 2 1& ( <0 8 <) D ) 2 13 ( 4.408 )4.) D ) 2 5.4. ie. + monitors. t he ) in the equation is the accommodation front monitors.
Foam proportioner Foam supply rate 7, as calculated abo/e 2 43+.4 lit8min @ixin# ratio, m 2 3 ? 1in this case. different mixin# ratio is possible depend#in# on the foam concentrate0 Gater flo" rate, G 2 7 x 1!! ( m0 8 !! 2 43+.4 x 1!! ( 30 8 !! 2 3.3 lit8min A proportioner is selected. 'n this case @H)!!, )!!A x 5!A "ith a flo" ran#e of 5! I 5!! lit8min. The main characteristic of the proportioner is that it "ill accurately proportionate the foam liquid at 3 ? upto a flo" of 43+.4 lit8min irrespecti/e of flo" rate or pressure.
Foam liquid pump Foam liquid pump capacity, $ 2 17 x m x +!0 8 1!! x !!!0 cu.m8hr $ 2 1 43+.4 x 3 x +! 0 8 1!! x !!!0 2 5.9 cu.m8hr
Minimum capacity of fire pump Supply rate, 7 2 43+.4 lit8min As per the rules, '-$ .3.!, the capacity of one applicator must be atleast 4!! lit8min. Also atleast t"o applicators in opeartion. So total of !! lit8min flo" required. @inimum fire pump capacity, $f 2 7 x 1!! ( m0 x +!8 1!!! x !! 0 D 7h x +! 8 !!! includes the f oam monitors and the applicator. $f 2 43+.4 x 9 x +! 8 1!!! x !!0 D !! x +! 8 !!! 2 539 cu.m8hr
