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In the early years of the oil industry, fire in astorage tank was a common occurrence. Virtuallyall products were stored in cone roof tanks built ofriveted steel plates and the roof was oftenconstructed with wood and tar coated paper.Tank fires were common especially after alightning storm. This costly experience graduallyled to improvements in better codes andguidelines for handling storage tank fires.Floating roof tanks were adopted for low flash
point petroleum products and proved to be a mostreliable method of protection against losses due tofires. The less volatile products with higher flashpoints continue to be stored in welded steel coneroof tanks.
As the frequency of fully involved storage tankfires decreases to a more acceptable level, thesize of fire, when it happens, becomes larger dueto the increase in tank size and capacity. It isquite common to see tanks with diameters in ex-cess of 328 ft. (100 meters) capable of storing amillion barrels of product
One practical method to protect flammable liquidstorage tanks from fire is with a fixed or a semi-fixed foam fire protection system. Whenengineered, installed and maintained correctly,these systems will give many years of reliableservice. The foam system can be used for fireprevention, control or direct extinguishment of anyflammable or combustible liquid fire within thetank.
In order to select the correct foam system, it isnecessary to understand the following systems:
A Fixed System is a complete installation piped
from a central foam station, discharging throughfixed discharge devices on the hazard being pro-tected. Foam proportioning components are per-manently installed.
A Semi Fixed System is an installation where thehazard is equipped with fixed discharge device(s)which connect to piping that terminates a safe
FIXED OR SEMI-FIXED
FOAM FIRE PROTECTION
SYSTEMS FOR STORAGE
TANKS
distance from the hazard. (Normally outside thedike wall.) Foam producing materials are trans-ported to the scene after the fire starts and areconnected to the piping.
DEFINITIONS
There are three major types of tanks commonlyused for the storage of combustible or flammableliquids.
Cone roof tank
Open top floating roof tank
Internal floating roof tank/Covered FloatingRoof
A Cone Roof Storage Tank has vertical sides
and is equipped with a fixed cone-shaped roofthat is welded to the sides of the tank. Tanks thathave been designed in accordance with APIstandards have a weak seam at the joint wherethe roof and sides meet. In the event of aninternal explosion, the roof separates and blowsoff leaving the tank shell intact. This system
allows the tank to retain its contents and anyresulting fire will involve the full surface of theexposed flammable liquid.
An Open Top Floating Roof Storage Tank is
similar to the cone roof tank in construction butwith the exception that it has no fixed roof. Apontoon type roof floats directly on the flammableliquid surface. This floating roof has a mechanicalshoe or tube seal attached to its full perimeter.The rim seal covers the space between thefloating roof and the tank shell ( side wall ).
An Internal Floating Roof/Covered Floating
Roof Storage Tank is a combination of both thecone roof and the open top floating roof tank.The tank has a cone roof but with the addition ofan internal floating roof or pan that floats directlyon the fuel surface. This type of tank can beidentified by the open vents in the tank side walls
just beneath the roof joint. If the internal floatingroof is other than a steel double deck or pontoon
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type, the fire protection system should bedesigned for full surface fires ( similar to cone rooftanks ). For the double deck or pontoon internalroofs of steel construction, a design for seal areaprotection shall be permitted (same as openfloating roof tanks).
Small quantities of flammable liquids aresometimes stored in horizontal style tanks whichnormally sit on saddles or in underground storagefacilities. This section applies only to the threemajor types of tanks as listed above.
IDENTIFY THE FLAMMABLE LIQUID
There are two basic classifications of flammableand combustible liquids:
Hydrocarbon ( non water miscible ) and Polar Solvent ( water miscible )
The Hydrocarbon family typically consists ofstandard petroleum products such as - Gasoline,Kerosene, Diesel, Jet Fuel, Heptane, Crude Oiletc. products that do not mix with water.
The Polar Solvent group typically consists of -Ethanol, Methanol, Ketone, Acetone etc. or pro-ducts that will mix readily with water.
All Chemguard U.L. Listed and Standard GradeFoam Concentrates are suitable for use on
Hydrocarbon fuel fires or spills.
Only Chemguard U.L. Listed and Standard GradeUltraGuard 3% and the 3%-6% ( at 6% propor-tioning rate ) Alcohol Resistant - Aqueous FilmForming Foam ( AR-AFFF ) concentrates aresuitable for use on Polar Solvent Fuel fires orspills.
NOTE: Pure MTBE is only slightly water miscible( approx. 4% - 6% ).
FLAMMABLE AND COMBUSTIBLE LIQUIDS
PER NFPA 11
Flammable liquids mean any liquid having a flashpoint below 100
o
F ( 37.8o
C ) and having a vaporpressure not exceeding 40 psi (276 kpa)(absolute)at 100
o
F ( 37.8o
C ).
Flammable Liquids are subdivided as follows:
Class I liquids include those having flash pointsbelow 100
o
F ( 37.8o
C ) and may be subdivided asfollows:
(a) Class IA liquids include those having flashpoints below 73
o
F ( 22.8o
C ) and having aboiling point below 100
o
F ( 37.8o
C ).(b) Class IB liquids include those having flash
points below 73o
F ( 22.8o
C ) and having aboiling point above 100oF ( 37.8
o
C ).(c) Class IC liquids include those having flash
points at or above 73o
F ( 22.8o
C ) and below100
o
F ( 37.8o
C ).
Combustible Liquids mean any liquid having aflash point at or above 100
o
F ( 37.8o
C ). They
may be sub-divided as follows:
(a) Class II liquids include those having flashpoints at or above 100
o
F ( 37.8o
C ) andbelow 140
o
F ( 60o
C ).(b) Class IIIA liquids include those having flash
points at or above 140o
F ( 60o
C ) and below200
o
F ( 93.3o
C ).(c) Class IIIB liquids include those having flash
points at or above 200o
F ( 93.3o
C ).
FIRE PROTECTION OF STORAGE TANKS
U.L. has established two different types of foamdischarge outlets:
Type II Discharge Outlet - A fixed device thatdelivers foam onto the burning liquid and partiallysubmerges the foam and produces restrictedagitation of the surface. Examples of this type ofdevice are Foam Chambers and Foam Makers.
Type III Discharge Outlet - A fixed or portabledevice that delivers foam in a manner that causesthe foam to fall directly onto the surface of theburning liquid in such a manner that causesgeneral agitation. Examples of this type of deviceare Hose Stream Nozzles and Monitors.
There are two basic methods of fire protectionsystems for storage tanks:
Sub-surface Base Injection
Over the Top - (Subdivided as follows)Foam ChambersFoam MakersPortable Foam MonitorFoam Tower
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SUB-SURFACE BASE INJECTION
The sub-surface method of fire protectionproduces foam with a "High Back Pressure FoamMaker" located outside the storage tank. Thissystem delivers the expanded foam mass throughpiping into the base of the tank. The pipe may bean existing product line or can be a dedicated fireprotection foam line. The expanded foam enteringthe tank through a discharge outlet is injected intothe flammable liquid. The discharge outlet mustbe a minimum of 1 ft. above any water that maybe present at the base of the tank. The foam willbe destroyed if injected into the water layer. Wheninjected into the fuel, the foam will rise through thefuel and form a vapor tight foam blanket on thefuel surface.
Advantages of Sub-surface
The rising foam can cause the fuel in the tankto circulate which can assist in cooling the fuelat the surface.
If there is an explosion and fire that coulddamage the top of the tank, the sub-surfaceinjection system is not likely to suffer damage.
The discharging foam is more efficientlydirected to the fuel surface without anyinterruption from the thermal updraft of thefire.
Disadvantages of Sub-surface
CANNOT be used in storage tanks containingpolar solvent type fuels or products thatrequire the use of AR-AFFF type foamconcentrates.
Not Recommended for use in either FloatingRoof or Internal Floating Roof type tanks.
Caution must be used so that the maximumfoam inlet velocity is not exceeded; otherwise,excessive fuel pickup by the foam as it entersthe tank will be experienced.
Not to be used for protection of Class 1Ahydrocarbon liquids.
HIGH BACK PRESSURE FOAM MAKER
The HBPFM device is mounted in the foam lineused to aspirate the foam solution before it isdischarged into the storage tank base. It willtypically give an expansion ratio of between 2 -1
and 4 - 1. The device is capable of dischargingagainst considerable back pressure which can beas high as 40% of the operating pressure. Theback pressure is an accumulation of the headpressure of the fuel inside the storage tank andany friction loss between the foam maker and thetank. A minimum of 100 psi inlet pressure into theHBPFM is normally required to ensure correctoperation. The foam velocity through the piping tothe tank from the HBPFM is very critical. Withflammable liquids, the foam velocity entering thetank should NOT exceed 10 ft. per second andwith combustible liquids the foam velocity shouldNOT exceed 20 ft. per second.
The following chart shows the minimum dischargetimes and application rates for Sub-surfaceapplication:
Hydrocarbon Minimum Minimum
Type Fuel Discharge Application
Time Rate
Flash point between 100oF and 30 min. 0.10 gpm / ft.
140oF (37.8oC and 93.3oC) 4.1 L/min./m
Flash point below 100oF 55 min. 0.10 gpm / ft.
(37.8oC) liquids heated above 4.1 L/min./m
their flash points.
Crude Petroleum 55 min. 0.10 gpm / ft.
4.1 L/min./m
NOTE: The maximum application rate shall be
0.20 gpm / ft. ( 8.1 L/min./m ).
FOAM CHAMBERSTYPE II DISCHARGE DEVICE
The Foam Chamber is normally used on coneroof storage tanks. The chamber is bolted orwelded on the outside of the tank shell near theroof joint. A deflector is mounted on the inside ofthe tank so that the discharging foam from thefoam chamber will be diverted back against theinside of the tank wall.
The foam chamber is mounted on the cone roofstorage tank wall shell in a vertical position just
below the roof joint, or approximately 8" to 12"down from the roof joint to the center point of thefoam chamber outlet.
In sequence Chemguard Models FC 2.2, 3, 4 and6 foam chambers are to be mounted from approx.8" to approx. 12" down from the roof joint.
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When the foam chamber is mounted correctly, theinternal glass seal of the chamber will be justslightly higher in elevation than the roof joint onthe storage tank.
Each foam chamber mounted on a cone roofstorage tank SHOULD have its own individuallyvalved riser supplying the foam solution fromoutside the dike area. For correct operation, aminimum of 40 psi is required at the inlet to thefoam chamber.
FOAM MAKERSTYPE II DISCHARGE DEVICE
The foam maker is normally used to aspirate foamsolution before being discharged inside a dike
(bund) area or when used with external floatingroof tanks to supply foam to the rim seal area.
The discharge pipe down stream of the foammaker is sized to slow the velocity of theexpanded foam and shaped to deflect the foamback against the inside of the dike wall or onto asplash board or the tank shell wall when used forfloating roof seal protection.
The splash board is to be mounted above the topof the floating roof tank. The correct sizedischarge pipe from the foam maker should beinstalled per the information supplied in the dikeprotection system design information.
When mounted on a storage tank or used in adike protection system, the foam maker can bemounted in either a horizontal or vertical position
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Discharge device - Foam Chamber, Qty. 4required
Discharge Duration - 55 min. 1,767.2 x 55 =
97,196 gallons of foam solution x .03 =2,915.88 gallons of 3% AFFF concentraterequired.
Supplementary Hose Lines required ( Per NFPA11) - Qty. 3 required ( each minimum 50 gpm ) (Tank dia. over 120 ft. )
Hose Line discharge duration ( Per NFPA 11) -30 min. ( Tank dia. over 95 ft. ) 3 x 50 = 150 x30 = 4,500 gallons of foam solution x .03 =135 gallons of 3% AFFF. 3,051 (135 + 2,916)gallons of foam concentrate required.
A suitable bill of materials of major components
for the above system using a bladder tank couldbe.
1 x 3,200 Gallon horizontal style bladder tank.
1 x 6" Between flange style ratio controller.
4 x Model FC6 foam chambers each with aflow rate of 395 to 1,050 gpm depending onincoming pressure.
1 x 2 1/2" Threaded type ratio controller (Forsupplementary system).
3 x 50 gpm handline nozzles.
foam concentrate.
NOTE:
This chart identifies the number of Foam Cham-bers required for the protection of a flammableliquid contained in a vertical cone roof atmos-pheric storage tank where the discharge device isattached to the tank. Where two or more outletsare required, the outlets are to be equally spacedaround the tank periphery and each outlet is to besized to deliver foam at approximately the samerate.
Tank Diameter Meters Minimum Number(or equivalent of discharge
area) outlets
Up to 80 ft. 24 1Over 80 to 120 24 to 36 2Over 120 to 140 36 to 42 3Over 140 to 160 42 to 48 4Over 160 to 180 48 to 54 5Over 180 to 200 54 to 60 6
It is suggested that for tanks above 200 ft. (60 m)in diameter at least one additional discharge outletbe added for each additional 5,000 sq. ft. ( 465sq. m. ) of liquid surface or fractional part.
This chart indicates the number of SUPPLE-MENTARY hose streams required for various sizetanks. Each hose stream must be capable of aminimum flow rate of 50 gpm of foam solution.
Diameter of Largest Minimum Number ofTank Hose Streams Required
Up to 65 ft. ( 19.5 m ) 165 to 120 ft. ( 19.5 to 36 m ) 2Over 120 ft. ( 36 m ) 3
This chart shows the Minimum discharge time andapplication rate for Type II fixed foam discharge
devices on Cone Roof storage tanks.
Hydrocarbon Application Discharge
Type Rate Time
Flash point between 0.10 gpm/ft . 30 min.
100o
F and 140o
F (4.1 L/min./m)
(37.8o
C and 93.3o
C)
Flash point below 100o
F 0.10 gpm/ft. 55 min.
(37.8o
C) or liquids heated (4.1 L/min./m)
above their flash points
Crude Petroleum 0.10 gpm/ft. 55 min.
(4.1 L/min./m)
Flammable liquids having a boiling point of lessthan 100
o
F might require higher rates ofapplication. These should be determined bytest.
For high-viscosity liquids heated above 200o
F,lower initial rates of application of foam may bedesirable to minimize frothing and thesubsequent expulsion of the stored liquid fromthe storage tank. Good judgment should beused in applying foams to tanks containing hotoils, burning asphalts or burning liquids thathave boiling points above the boiling point ofwater.
The above table includes Gasohols andunleaded gasolines containing no more than10% oxygenated additives by volume. Wherethese additives exceed 10% by volume orwhere the flammable liquid is a polar solvent orwater miscible product, fire protection isnormally supplied by the AR-AFFF type foamconcentrates. In those instances check with
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Chemguard to establish recommended appli-cation rates. The minimum discharge durationis 55 min.
The following chart indicates the minimumoperating time of the supplementary hosestream(s) for various size tanks.
Diameter of Largest Minimum OperatingTank Time
Up to 35 ft. ( 10.5 m ) 10 min.35 to 95 ft. ( 10.5 to 28.5 m ) 20 min.Over 95 ft. ( 28.5 m ) 30 min.
Equipment List using a Foam Pump Skid Assy.for a 150 ft. dia. tank containing gasoline.
1 x Atmospheric Foam Concentrate StorageTank 3,100 Gallons
1 x Electric powered Foam Pump Proportioningskid with prepiped 6" ratio controller ( FoamChambers ) and prepiped 2 1/2" ratiocontroller ( Supplementary Hose Lines )
4 x Model FC4 or FC6 Foam Chambers
3 x 50 gpm Hand Line nozzles
3,051 x Gallons 3% AFFF ( plus any additionalfor testing of the system )
NOTE:
When protecting multiple storage tanks the foamsystem is to be sized to protect the single largesthazard.
Fig. 9 depicts a manual foam pump skid systemshowing all necessary piping, valves, dischargedevices, ratio controller, foam pump and foamstorage tank for the above system.
Fig. 10 shows a Cone Roof Storage Tank with aSemi-Fixed Foam System.
The following example shows the foam systemrequirements for seal protection of a 150 ft.diameter open top floating roof tank.
Type of Tank - Open Top Floating Roof Tank
Diameter of Tank - 150 ft.
Type of Fuel - Gasoline
Foam Dam installed on roof - Yes - 2 ft. fromtank wall and 2 ft. in height
Sq. ft. area of annular ring - 930 sq. ft.
Application Rate - .30 gpm per sq. ft. ( PerNFPA 11).30 x 930 sq. ft. = 279gpm of foam solution required.
Type of Discharge Device - Foam Makers
Discharge Duration - 20 min.279 x 20 = 5,580 gallons of foam solution - x.03 ( 3% AFFF ) = 167.4 gallons of foamconcentrated
Quantity of Foam Makers Required ( Per NFPA
11) 6 required.
Add supplementary hose lines per example forCone Roof Tank with Foam Chambers.
NOTE:
The number of fixed foam discharge points on anopen top floating roof tank is determined by thecircumference of the tank.
The maximum spacing between discharge pointsis 40 ft. ( 12.2 m ) of tank circumference when
using a 12" ( 305 mm ) high foam dam and every80 ft. ( 24.4 m ) of tank circumference when usinga 24" ( 610 mm ) high foam dam.
In accordance with NFPA 11
Foam Dam Design - The foam dam should becircular and constructed of at least No. 10 USStandard Gage Thickness ( .134 in./3.4 mm )steel plate. The dam is to be welded or otherwisesecurely fastened to the floating roof. The foamdam is designed to retain foam at the seal area ata sufficient depth to cover the seal area whilecausing the foam to flow laterally to the point of
seal rupture.
Dam height is to be at least 12" ( 305 mm ) andshould extend at least 2" ( 51 mm ) above anymetal secondary seal or a combustible secondaryseal using a plastic foam log.
It is to be at least 2" ( 51 mm ) higher than anyburnout panels in metal secondary seals.
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Foam dams are to be at least 1 ft. ( 0.3 m ) butno more than 2 ft. ( 0.6 m ) from the edge of thefloating roof.
Foam solution & rain water is to be drained by,slotting the bottom of the dam on the basis of 0.04sq. in. of slot area per sq. ft. (278 mm sq./sq. m)of diked area while restricting the slots to 3/8 in.(9.5 mm) in height. Excessive dam openings fordrainage should be avoided to prevent loss offoam through the drainage slots.
SUB-SURFACE SYSTEM
( Sub-surface injection of foam is generally notrecommended for fuels that have a viscositygreater than 2,000 ssu ( 440 centistokes ) at theirminimum anticipated storage temperature ).
Example of a Sub-Surface Base Injection System
Cone Roof Tank - 80 ft. diameter
Fuel - Gasoline
Foam Concentrate - 3%-6% AR-AFFF
Surface Area - =40' x 40' x 3.1417 = 5,026.7 sq. ft.
App. Rate - .10 gpm per sq. ft..10 x 5,027 sq. ft. = 502.7 gpm of foam solution
Discharge Duration - 55 min.
Quantity of Foam Concentrate required -503 (502.7 ) x 55 x .03 = 829.95 gallons
Discharge Device - Qty. 1 High Back PressureFoam Maker ( " Foam generator " )
Number of Discharge outlets inside tankQty. 1 (Tank 80 ft. or less) (Per NFPA 11)
Supplementary hose lines per example for ConeRoof Tank.
The following chart shows the number of dis-charge outlets required inside the tank.
Tank Diameter Number of Discharge Outlets Required
Fl ash Point below Flash Point 100oF
100o
F (38o
C) (38o
C) or Higher
Up to 80 ft. ( 24 m ) 1 1
Over 80 to 120 ft. ( 24 - 36 m ) 2 1
Over 120 to 140 ft. ( 36 - 42 m ) 3 2
Over 140 to 160 ft. ( 42 - 48 m ) 4 2
Over 160 to 180 ft. ( 48 - 54 m ) 5 2
Over 180 to 200 ft. ( 54 - 60 m ) 6 3
Over 200 ft. ( 60 m ) 6 3
Plus 1 outlet for Plus 1 outlet for
each additional each additional
5,000 sq. ft. 7,500 sq. ft.
(465 sq. m) (697 sq. m)
Equipment list for the above example using abladder tank foam supplied foam system.
1 x 900 Gallon vertical style bladder tank.
1 x 4" Between flange style ratio controller.
1 x 2 1/2" Threaded type ratio controller ( forsupplementary hose lines ).
1 x Model CFM500 High Back Pressure FoamMaker ( HBPFM ).
Supplementary hand line nozzles and foamconcentrate.
Determining Number of Discharge Outlets forSubsurface Base Injection.
The number of discharge outlets required is bas-ed on the tank diameter and the flash point of thefuel as shown in the above chart.
FOAM MONITORS AND HANDLINES
Monitors are not to be considered as the primarymeans of protection for fixed roof tanks over 60 ft.in diameter. Foam handlines are not to beconsidered as the primary means of protection fortanks over 30 ft. in diameter or those over 20 ft. inheight.
Application Rates Using Monitors orHandlines
The minimum foam solution application rate isbased on the assumption that all discharging foamwill reach the area being protected. In consider-ing actual solution flow requirements, considera-tion should be given to potential foam losses fromclimatic conditions and thermal updraft of the fire,etc.
The following chart shows application density andduration for monitors and handlines on tankscontaining hydrocarbons.
Hydrocarbon Type Minimum MinimumApplication Rate Discharge
gpm/ft2 (L/min.)/m2 Time
(min.)
Flash point between
100oF and 140oF
(37.8oC and 93.3oC) 0.16 6.5 50
Flash point below 100oF
(37.8oC) or liquids heated
above their flash points 0.16 6.5 65
Crude Petroleum 0.16 6.5 65
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Included in the above table are gasohols andunleaded gasolines containing no more than 10percent of an oxygenated additive by volume.
On tanks containing water miscible/polar solventflammable liquids the recommended foam appli-cation duration is 65 minutes.
Flammable liquids having a boiling point less than100oF and products that have been burning forsome time can develop a heat layer which mightrequire foam solution application rates as high as.2 or .25 gpm per sq. ft.
Where monitors or handlines are used to protectstorage tanks containing polar solvent or watermiscible liquids the discharge duration shall be aminimum of 65 minutes at the recommendedapplication rate.
FSFPrv 995
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TECHNIQUE IN EXTINGUISHING LARGETANK FIRES
Large storage tank fires are very complex eventsand satisfactory extinguishment requiresmethodical planning and the effective use ofresources. At this time, existing Codes andStandards do not provide guidelines for using highflow monitor foam applications for large tank fires.The existing Codes and Standards do providegood recommendations for fixed fire protectionsystems. Full surface fires involving largediameter tanks have occurred around the world.Extinguishment of such fires has not been totallysuccessful. With the introduction of large capacityfoam monitors, new varieties of foamconcentrates and improvements in applicationtechniques there has been some degree ofsuccess in achieving extinguishment.
The largest fully involved tank fire that has beensuccessfully extinguished was 150 ft. (46 meter).The extinguishment was carried out with a largecapacity monitor/cannon applying non-aspiratedfoam "over-the-top" onto the burning surface. It is
believed that present fire fighting technology iscapable of extinguishing fully involved tank firesup to 197 ft. (60 meters) in diameter. In theory itmay be technically feasible to extinguish tank firesin excess of 200 ft. (61 meters) using the "over-the-top" method of employing very large capacitymobile monitors with improved types of foamconcentrates. The logistics for mounting suchmassive operations must be fully considered.
APPLICATION RATE
NFPA 11 application rate for mobile equipment isoften interpreted as 0.16 gpm/ft2. (6.5 L/min./m7).
The code also states that flammable liquidshaving a boiling point of less than 100
o
F (37.8o
C)may require higher rates of application. In addi-tion flammable liquids with a wide range of boiling
STORAGE TANK
PROTECTION WITH HIGH
FLOW MONITORS
points such as Crude Oil may require applicationrates of 0.2 gpm/ft2. (8.1 L/min./m2) or more. Theapplication rate stated in the code is based on theassumption that all the foam solution reaches theburning surface.
Note: The rates are intended for Liquid Hydro-
carbon Fuels. Polar solvent liquids are destruc-tive to regular foams and require the use ofalcohol resistance foams. Chemguard, Inc.should be consulted to determine the recom-mended application rate.
In view of the above, rates and practicalexperience gained in incidents involving fullsurface fires involving large storage tanks, itwould be more appropriate to consider 0.25gpm/ft2. (10.4 L/min./m2) which is equal to a 60%increase for mobile systems. For burning crudeoil tank a rate of 0.32 gpm/ft2. (12.9 L/min./m2)may be more appropriate.
The elevated application rates provide a better
chance of ensuring foam reaching the burningsurface thus increasing the probability for extin-guishment. Consideration for such high ratestake into account fall out from the delivery system,losses due to strong thermal updraft, break downof foam as it travels through the flames to reachthe burning fuel and destruction of the foam dueto the hot fuel and any hot metal surface.
WATER AND FOAM CONCENTRATE RE-QUIRED FOR FIGHTING LARGE TANK FIRES
Water supply both in terms of pressure, flow rateand adequate amount of foam concentrate areamong the most important factors for launching asuccessful extinguishing operation. Unless ade-quate and uninterrupted supply is guaranteed, anattempt to extinguish a fully involved large tankfire is doomed to failure at the very onset of theoperation.
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The amount of water and the flow rate needed toproduce 3% foam solution to generate foam tofight a large tank fire can be found in Table 1.
The quantity of 3% foam concentrate and the flowrate needed to produce 3% foam solution togenerate foam to fight a large tank fire can befound in Table 2.
COOLING INVOLVED TANK AND THE PRO-TECTION OF ADJACENT TANKS FROM RADI-ATED HEAT SOURCE
With reference to existing guidelines, the amountof water needed to cool the involved tank shell isestimated by tank size:
100 ft. (30 meter) diameter 750 gpm (3m3/min.)120 ft. (36 meter) diameter 1000 gpm (4m3/min.)160 ft. (48 meter) diameter 1250 gpm (5m3/min.)220 ft. (67 meter) diameter 1500 gpm (6m3/min.)
Cooling water required to protect each adjacenttank not shielded from the tank on fire is 500 gpm(2 m3/min.).
In practice water applied to the shell of a largetank on fire is ineffective in preventing it frombuckling and deforming. In the late stages ofextinguishment, cooling water applied on the areaabove the liquid level would help the foam stay in
contact with the tank shell. The cooling streamsshould be stopped when foam attack has startedto conserve water and to concentrate on extin-guishment.
The need for protecting adjacent tanks can bestbe illustrated with information and data publishedin a recent study done on large tank fires.Although not yet fully validated it neverthelessprovides valuable information for pre-fireplanningpurposes.
The time required to create an escalation condi-tion in an adjacent tank depends upon a number
of factors including: tank size, separation, type,initial boiling point of flammable liquid in the tanks,water cooling, tank design, wind speed anddirection.
For example, a full surface fire involving a 164 ft.(50m) diameter open top, floating roof naphtha
tank fire could be expected to fully involve aneighboring identical tank in approximately 1.5hours under the following conditions.
- 4 m/sec.(14 km/hr.) wind towards neighboringtank
- intertank separation of 0.5 diameter(82 ft.) (25 m)
- neighboring tank having pontoon roof andinadequate water spray protection
Altering any of the above conditions can changethe time for ignition of the adjacent tank:
Base Case = 1.5 hrs.
Change of conditions:
Calm (no wind condition) = 2.8 hrs.Intertank separation increased to 1.0 D (50 m)
= 3.0 hrs.Intertank separation increased to 2.0 D (100 m)
= 17.0 hrs.Water protection on side facing exposure
= 2.8 hrs.Double deck roof on exposed tank
= 1.5 hrs.Water protection on side facing exposure +double deck roof = 24.0+hrs.Tank diameters only 30 m but with 0.5 Dseparation = 0.5 hrsNeighboring tank contains kerosene, not naphtha
= 22.0 hrs.
Some conclusions drawn from the results are:
escalation is likely for unprotected tanks ofvolatile material with normal separation unlessthe original fire is extinguished quickly
calm conditions only delay the escalationpotential
increased separation alone only delays theescalation potential
water spray protection or roof insulation alonedoes prevent escalation
water spray and roof insulation together are
effective
smaller diameter tanks at normal separationare at greater risk of escalation than largerdiameter tank
lower volatility fuels provide more responsetime for fire fighter
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Cooling of adjacent tanks is best achieved withfixed systems that are designed to provide effec-tive water film coverage of all exposed metalsurfaces. A cooling water rate of 0.05 gpm/ft2.(2.0 L/min./m2) is sufficient to absorb 90% ofincoming radiant heat. Any increase in the
cooling water rate does not increase the coolingeffect significantly. The figure of 10.2 L/min./m2
by NFPA 15 relates mainly to the protection ofpressurized vessels such as LPG tanks subject todirect flame impingement.
OVER THE-TOP-APPLICATION TECHNIQUEWITH LARGE CAPACITY FOAM MONITORS
A present concept in extinguishing large tank firesis to employ Large Capacity Non-aspirated FoamMonitors to apply foam "over-the-top" of theinvolved tank onto the burning fuel surface.
Although they are normally known as non-aspirated monitors, these monitors are capable ofproducing foam with an expansion ratio of about3.1 to 4.5 when used with alcohol resistance typefoam concentrates.
Chemguard has large capacity foam monitorscurrently available have capacities ranging from2,000 to 4,000 gpm (7,570 L/min.). The equip-ment operates at inlet pressure between 100 to130 psig (690 to 890 kPa) and have a range ofabout 250 to 300 feet (61-99 meter).
AR-AFFF type foam concentrate is preferred and
it should be transported in bulk totes or trailershaving large capacities. The logistics for trans-porting foam in 5 gallon pails or 55 gallon drumsto the fire scene should not be considered, forobvious reasons.
Large diameter hose should be used to supply theflow required for large volume foam attack. Theuse of 5" (125 mm) diameter hose is preferreddue to low frictional loss and is relatively easy touse. It must be remembered that it is extremelydifficult to move the hose once it is charged withwater. For quick estimation, provide one 5" (125mm.) hose line for every 1,000 gpm (3.8 m3/min.)
flow requirement. At this flow rate the friction lossis 8.0 psig (55 kPa) for every 100 feet (30.5 m).Table 3 provides information on friction loss ofsome large diameter hoses.
The over-the-top foam technique attacks theburning tank with either a very large capacitymonitor that meets the required application rate or
combines several monitors to form a MassStream discharging with the wind to concentrateon a selected landing zone within the tank.
This extremely high local application rate/densitypromotes survivability of the foam journey through
the fire to establish a foothold on a relatively smallarea of the burning surface. Once the foamblanket at the landing zone is established it canthen be expanded by making adjustments to theMass Stream. The added advantage of largevolume application in a small area may help toreduce local fuel temperature and the associatedactual vapor presssure which in turn can help inlowering the fire severity. These factors requireconsideration because as the fuel temperatureapproaches the boiling point of water, it is difficultfor the foam to survive. As fuel temperatureincreases the true vapor temperature will increaseto overcome the effectiveness of the foam
blanket.
Large volume foam attack should be launched asquickly as possible; however, it must be stressedthat application must not be carried out until allequipment and logistic support are in place. Thelonger a tank is allowed to burn, the danger ofescalation becomes greater, the fuel temperatureincreases making it more difficult to extinguish,the exposed tank shell deforms (normally theexposed steel curls inwards to create nooks andcrevices) making it difficult for foam to cover allthe burning surface. In the case of crude oil, thepossiblility of having a boilover increases with
time.
The ability to deal with large tank fires depends onmethodical pre-fire plan, regular training andexervises. The most important factor, however,rests on minimizing the risk of having a fullyinvolved large tank fire through good engineeringdesign, effective management and maintenanceprograms.
STPrv995
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
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Fuel
Foam
Wind
Monitor
OVER-T
HE-T
OP
FOAMAPPLICATIONTECHNIQUE
WITHLARGE
CAPACITYFOAMMO
NITORS
D021rv895
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
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TABLE1
WATERFLO
WR
ATETOPRODUCE3%
FOAMSOLUTION
TOFIGHTFIRESINTANKS
MINIMUMQUANTITIES
TANKDIAMETER
WATERFL
OWR
ATE
TOTALWATERREQUIREDTOS
USTAIN
65MINUTESOFOPERATIO
N
Feet
Mete
r
ApplicationRate
ApplicationRate
ApplicationRate
ApplicationRate
0.16gpm./ft2.
6.5L/min./m2
0.25gpm./ft2.10.4L/min./m2
0.16gpm./ft2.6.5L/min./m2
0.25gpm./ft2.
10.4L/min./m2
Gallon
Meter3
Gallon
Meter3
100
30.5
1218
4598
1904
7357
79170
299
123760
478
110
33.5
1474
5563
2304
8902
95796
362
149750
579
120
36.6
1754
6621
2742
10594
114005
430
178214
689
130
39.6
2058
7770
3218
12433
133797
505
209154
808
140
42.7
2387
9012
3732
14420
155173
586
242570
937
150
45.7
2741
10345
4284
16553
176133
672
278460
1076
160
48.8
3118
11770
4874
18834
202675
765
316826
1224
170
51.8
3520
13288
5503
21262
226801
864
357666
1382
180
54.9
3946
14897
6169
23837
256511
968
400982
1549
190
57.9
4397
16598
6873
26558
285804
1079
446774
1726
200
61.0
4872
18391
7616
29425
316680
1195
495040
1913
210
64.0
5371
20276
8397
32444
349140
1318
545782
2109
220
67.1
5895
22253
9216
35606
383183
1446
598998
2315
230
70.1
6443
24322
10072
38916
418809
1581
654690
2530
240
73.2
7016
26483
10967
42376
456019
1721
712858
2754
250
76.2
7613
28736
11900
45981
494813
1868
773500
2989
260
79.2
8234
31081
12871
49733
535189
2020
836618
3233
270
82.3
8879
33518
13880
53632
577149
2179
902210
3486
280
85.3
9549
36047
14927
57679
620693
2343
970278
3749
290
88.4
10243
38667
16013
61872
665820
2513
1040822
4022
300
91.4
10962
41380
17136
66213
712530
2690
1113840
4304 C
HARrv895
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
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TABLE2
FOAMCONCENTRAT
E(3%)TOPRODUCE3%
FOAMSO
LUTION
TO
FIGHTFIRESINTANKS
MINIMUMQUANTITIES
TANKDIAMETER
3%FOAMCONCENTRATE
FLOWR
ATE
TOTA
L3%FOAMCONCENTRATEREQU
IRED
TO
SUSTAIN65MINUTESOFOPERAT
ION
Feet
Meter
ApplicationRate
ApplicationRate
ApplicationRate
ApplicationRate
0.16gpm./ft2.
6.5L/min./m2
0.25
gpm./ft2.10.4L/min./m2
0.16gpm./ft2.6.5L/min./m2
0.25gpm./ft2.10.4L
/min./m2
Gallon
Meter3
Gallon
Meter3
100
30.5
38
142
59
228
2470
9.25
3835
14.79
110
33.5
46
172
71
275
2989
11.19
4640
17.89
120
36.6
55
205
85
328
3557
13.31
5522
21.30
130
39.6
64
240
100
385
4174
15.62
6481
24.99
140
42.7
74
279
116
446
4841
18.12
7617
28.99
150
45.7
86
320
133
512
5558
20.80
8629
33.27
160
48.8
97
364
151
582
6323
23.67
9818
37.86
170
51.8
110
411
171
658
7138
26.72
11063
42.74
180
54.9
123
461
191
737
8003
29.95
12425
47.92
190
57.9
137
513
213
821
8917
33.38
13844
53.39
200
61.0
152
569
236
910
9880
36.98
15340
59.16
210
64.0
168
627
260
1003
10893
40.77
16912
65.22
220
67.1
184
688
286
1101
11955
44.75
18561
71.58
230
70.1
201
752
312
1204
13066
48.91
20287
78.23
240
73.2
219
819
340
1311
14227
53.25
22090
85.18
250
76.2
238
889
369
1422
15438
57.78
23969
92.43
260
79.2
257
962
399
1538
15697
62.50
25925
99.97
270
82.3
277
1037
430
1659
18006
67.40
27957
107.81
280
85.3
298
1115
463
1784
19365
72.48
30068
115.94
290
88.4
320
1196
496
1913
20773
77.75
32252
124.37
300
91.4
342
1280
531
2048
22230
83.21
34515
133.10 C
HARrv895
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
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TABLE3
FRICT
IONLOSSPER100FEET/30.5MET
ERS
FRICTIONLOSSINWATERSUPPLYLINE
EXPRESSEDASPSIG&kPaLOSS
PER100FEET/30.5METERSOFH
OSE
FLOW
4INCHSUPPLYLINE
4-1/2INCHSUPPLYLINE
5INCHSUPPLYLINE
6INCHSUPPLYLINE
USGPM
LITER/MIN.
PSIG
kPa
PSIG
kPa
PSIG
kPa
PSIG
kPa
100
369
0.20
1
0.10
1
0.06
1
0.05
0.3
200
737
0.80
6
0.40
3
0.32
2
0.20
1
300
1106
1.80
12
0.90
6
0.72
3
0.45
3
400
1474
3.20
22
1.00
10
1.28
9
0.80
6
500
1843
5.00
34
2.50
17
2.00
14
1.25
9
600
2211
7.20
50
3.60
25
2.88
20
1.80
12
700
2580
9.80
68
4.90
34
3.92
27
2.45
17
800
2948
12.80
88
6.40
44
5.12
35
3.20
22
900
3317
16.20
112
8.10
56
6.48
45
4.05
28
1000
3685
20.00
138
10.00
69
8.00
55
5.00
34
1100
4054
24.20
167
12.10
83
9.68
67
6.05
42
1200
4422
28.80
199
14.40
99
11.52
79
7.20
50
1300
4791
33.80
233
16.90
117
13.52
90
8.45
58
1400
5160
39.20
270
19.60
135
15.68
108
9.80
68
1500
5628
45.00
310
22.50
155
18.00
124
11.25
78
1600
5897
51.20
353
25.60
177
20.48
141
12.80
88
1700
6265
57.80
399
28.90
199
23.12
156
14.45
100
1800
6634
64.80
447
32.40
223
25.92
179
16.20
112
1900
7002
72.20
496
36.10
249
28.88
199
18.05
124
2000
7371
80.00
552
40.00
276
32.00
221
20.00
138
2100
7739
88.20
608
44.10
304
35.28
243
22.05
152
2200
8106
96.80
667
48.40
334
38.72
267
24.20
167
2300
8476
105.80
729
52.90
366
42.32
292
26.45
182
2400
8845
115.20
794
57.60
397
46.08
308
28.80
199
2500
9214
125.00
862
62.50
431
50.00
345
31.25
215 C
HARrv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
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EXAMPLE OF BALANCE PRESSURE PUMPSKID WITH TWO PROPORTIONERS
WaterInlet
FoamConcentratePump
Flush InletConnection
Flush OutletConnection
Atmospheric Tank
Pressure ReliefValve
BalancingValve
RatioController
Strainer
System1: Foamsolutionto manifold supplying 4 foamchambers on cone roof tank.
System 2: Foam solution to
separate storage tank systemor hose reels, if required.
Pressure VacuumVent
FIG. 9
D004rv895
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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FUEL
AeratedFoam
FoamChamber
Dike Wall
FoamChamberTopsideApplication
on Cone Roof Tank
SEMI-FIXED FOAM SYSTEM WITH MOBILE
APPARATUS SUPPLYING THE FOAM SOLUTION
FIG. 10
Foam Solutionfrom MobileApparatus
OS & Y Valve
D085rv995
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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FUE
L
Foam
Blanket
Aerated
Foam
T
estPoint
HighBackPressure
FoamMaker
Foam
Solution
Rupture
Disc
(optional)
GateValve
Check
Valve
DikeWall
WaterLevel
SUB-S
URFAC
EINJECTIONAPPLIC
ATION
ON
CONEROOFTANK
D003rv995
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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Connections for Sub-surface Foam Makers
ValvedTest ConnectionRupture Disc
(optional)2 Outlets
Dike Wall
3 Outlets
4 Outlets
TYPICAL OUTLETS FOR SUB-SURFACE INJ ECTION
INSIDE CONE ROOF STORAGE TANKS
Gate Valve
Check Valve
D023rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
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Recommended
A.
Straight-In
C.H
orizontalELL
Recommended
B.
VerticalELL
NotRecommended
D.180ELL
o
NotR
ecommended
E.
HorizontalTee
Recommended
A B C D.BestforConeRoofTanks
.PossibletoBlockwithSediment
.GoodforFloatingRoofTanks(FRT)
.NotGoodforFRT,GivesStreamBacklash
TYPICALSUB-S
URFA
CETANKPROTECTIO
NINLETDESIGN
TankShell
Valve
Water
Bottom
90ELL
o
Plan
Elev.
Tee
Plan
Elev.
90ELL
o
180ELL
o
E.BestforFloatingRoofTank
D019rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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EXPANDED FOAM VELOCITY vs PIPE SIZE2 1/2", 3", 4", 6", 8", 10", 12", 14"
Standard Schedule 40 Pipe
All dimensions in inches (millimeters)
unless otherwise noted
EXPANDED FOAM RATE
FOAM VELOCITY vs PIPE SIZE - 16", 18"Standard Schedule 40 Pipe
16"
(400)
18"
(460)
All dimensions in inches (millimeters)
unless otherwise noted.
M/SEC
FT/SEC
9.1 30
6.1 20
3 10
0
FOAMVELOCITY
GPM
LPM
2000
7570
4000
15139
6000
22710
8000
3027810000
37848
12000
45420
14000
52990
16000
60560
EXPANDED FOAM RATE D038rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
22/35
0 200 400 600 800 1000 1200 1400 1600 1800
FOAM FLOW - gpm
FOAM FLOW - gpm
60
50
40
30
20
10
50
40
30
20
10
FOR SIUNITS1 gpm=3.785 / min.
1psi =6.895 kPa1 ft. =0.305m
l
FOR SIUNITS1 gpm=3.785/ min.
1psi =6.895kPa1 ft. =0.305m
3"P IPE DIAMETER
2 1/2"P IPE DIAMETER
0 400 800 1200 1600 2000 2400 2800 3200
4" PIPE DIAMETER
These subsurface graphs depict the friction loss characteristics of foamwith an expansion of 4 to 1 and inletvelocities for various pipe sizes. The 4 to 1 ratio is the value to be used for friction loss and inlet velocity
calculations.
D075rv195
FRICTION LOSS OF EXPANDED FOAM
THROUGH VARIOUS SIZE PIPES
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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FOAM FLOW - gpm
FOAM FLOW - gpm
50
40
30
20
10
0
FOR SI UNITS1 gpm=3.785 / min.
1psi =6.895kPa
1ft. =0.305m
l
1600 2400 3200 4000 4800 5600 6400 7200 8000 8800
6" PIPE DIAMETER
FOR SIUNITS1 gpm=3.785 / min.
1psi =6.895kPa
1 ft. =0.305m
l
0 4000 8000 12000 16000 20000 24000 28000 32000
14" PIPE DIAMETER
25
20
15
10
5
8" PIPE DIAMETER
10" PIPE DIAMETER
D076rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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FOA
MCHAMBERINSTALL
ATION
FIXEDSYSTEMUSINGABLAD
DERTANK
Foam
Chamber
SolutionFlow
Proportione
r
Water
Supply
BladderTank
BallValve
Normally
Closed
BallValve
Normally
Open
SwingCh
eck
Hydraulic
Actuated
BallValve
D010rv1296
Engr. Salman Ali SyedSEC-SOA, Abha
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FUEL
Foam
Chamber
FoamSolution
Aerated
Foam
Vent
Internal
Floating
Roof
Dik
eWall
FOAMCHAMBERTOPSIDEAPPLIC
ATION
ONINTERNALFLOATINGROOFTANK
D003rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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INSTALLATIONOF
FOAMMAKER&SPLASHBOARD
ONFL
OATINGROOFTANKS
Sheetsteelsplashboardcanberectangularorcutasshown
mountedonto
pofshellreinforcedwithsuitablesupports.
Minimumdime
nsionswilldependonminimumclearanceneeded
betweenfoam
dischargeoutletandtoppositionofroof.
"L"ShieldLength
3/8of"L"
FoamMaker
1/2of"A" W
indGirder
Foamsolution
pipingtootherfoammakersmay
belocatedabo
veorbelowwindgirderor
atgradelevel.
SwingJoint
"A"
12"
SplashBoard
FoamDam
2'0"
12"
Roof
UrethaneSeal
TankShell
FoamS
olution
Supply
Piping
Deflector
"A"Dimensionistheheighto
fthefoammakeroutlet
abovethetopedgeofthetan
kshell.Theminimum
heightmustclearthetoppositionofthefloatingroof.
D040rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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Foam Maker
Foam Solution
Weather Shield
AspiratedFoam
Seal
Typical BelowSeal ApplicationTypical Topof Seal Application
PontoonRoof
FoamDam
Aerated Foam
FoamSolution
FoamMaker
EXAMPLES OF TYPICAL TOP AND BELOW SEAL
APPLICATIONS FOR FLOATING ROOF TANKS
Brace
D005rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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Quick Opening Valve
Siamese Foam Hydran
StairwayPlatform
Stairway
Wind Girder
Solution Piping
Tank Shell
SEAL AREA PROTECTION USING A FOAM MAKEROR HANDLINE NOZZLE FROM LADDER AREA
FoamDam
Back Board MountedHigher than Uppermost
Position of Roof
Ladder
Brace
Floating Roof
Product
Foam
D022rv195
Foam Maker
Siamese Foam OutletforHandline Connection
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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29/35
Tank
Tank
Tank
Water
Supply
Monitor
(Typical)
Dike
TANKANDDIKEPROT
ECTIONWITHFOAMM
ONITORSYSTEM
OS
&Y
Va
lve
O
S&YValve
M
onitor
R
atio
C
ontroller
Foam
Concentrate
D033rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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A-BFoamChamber
MechanicalFoam
Generato
rConversion
FoamSolution
DeliveryPiping
STORAGETANKPROTECTION
T
opsideApplications
Dike
Existingor
New
FoamChamber
FoamSolution
DeliveryPiping
Dike
FoamDeliveryPipe
ForcingFoamMaker
Solution
DeliveryPiping
Dike
Dike
PortableFoam
TubeorTower
FoamSolution
DeliveryHoses
FixedFoamChamber
Fo
amMaker
Portab
leFoamTower
A-B
PowderConversion
FoamSolution
DeliveryPiping
FoamMaker
D016rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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Swing
Check
Valve
GateValve
Tank Shell
Foam
Flow
Valved Test Connection
Rupture Disc
(optional)
From High Back
Pressure Foam MakerAt Least 1 ft.
(0.3m)
Water Bottom
D012rv195
TYPICAL ARRANGEMENT FOR SUB-SURFACE SYSTEMSINTO A CONE ROOF STORAGE TANK
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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Dike
Dike
Solution
Delivery
Piping
Foam
Delivery
Piping
Normal
Water
Bottom
Product
Line
Solution
Piping
STORA
GETANKPROTECTIO
N
Sub
-surfaceApplications P
roductionLineApplication
Althoughdedicatedlinesmaybeusedtoapplyfoamusingthesubsurfacemethod,
additionaleconomiesmayberealizedbyusingexistingproductlinesforfoam
injection.
Insomeinstallationsatotaltankfarmmaybecoveredbyusingas
inglesubsurface
injectionstationattheproductlinemanifold.
Thepipingpressurelossesa
ndtheinletinjectionvelocitymustbev
erifiedbycalculation.
Thisistobedonewitheachproductlinewhichisacandidateforsu
bsurfaceinjection.
HighBackPressure
FoamMaker
HighBackPressure
FoamMaker
(HydrocarbonFuelsOnly)
DedicatedFoamSolution
LineApplication
D017rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
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Mechanical Shoe Seal.1 - For each 130 ft. (39.6 m) of tank circumference
(no foam damrequired)Tube Seal - Over 6 in. (15.2 cm) fromtop of seal to top ofpontoon with foam outlets under metal weather shield orsecondary seal.1 - For each 60 ft. (18.3 m) of tank circumference
(no foamdam required)Tube Seal - Less than 6 in. (15.2 cm) fromtop of seal totop of pontoon with foam outlets under metal weathershield or secondary seal.1 - For each 60 ft. (18.3 m) of tank circumference
[foam damat least 12 in. (30.5 cm) high required].
0.30 gpm. (1.14 L/min.) per sq. ft. (sq. m) of annular ringarea with foam damor with foam application under metalweather seal or secondary seal. 0.50 gpm(1.9 L/min.) persq. ft.. (sq. mfor all other applications).
20 min. - with foamdam or under metal weather shield orsecondary seal.
Notcovered by NFP A 11.
Monitors not recommended.
Handlines are suitable for extinguishment of rimfiresin open-top floating roof tanks.
0.16 gpm/ft.
(6.5 L/min./m )For rimfires in open-top floating roof tanks.
2
2
Use same times as for open-top floating roof tank rimfires.
Not Recommended.
Not Recommended.
Not Recommended.
Not Recommended.
Not applicable.
Not Applicable.
Not Applicable.
Not Applicable.
Monitors for tanks up to 60 ft. (18.3m) indiameter.Hand hoselines for tanks less than 30 ft.(9.2 m) in diameter and less than 20 ft.(6.1 m) high.
0.16 gpm/ft.
[(6.5 L/min.)/(m )]
2
2
Flash point below100 F (37.8Flash point 100 F - 140 F
C)
Crude Oil
o o
o o
Same as table for foamchambers.
Minimum0.1 gpm/ft. [(4.1 L/min.)/m. ] ofliquid surface.Maximum0.2 gpm/ft. [(8.2 L/min.)/m. ]Foamvelocity from outletshall not exceed10 ft. per sec. (3.05 m per sec.) for Class 1Bliquids or 20ft. per sec. (6.1 m per sec.) forall otherliquids.
2 2
2 2
Flash point100 F (37.8 C)to 140 F (194.4 C)
Flash point below100 F (37.8 C)Crude Petroleum
o o
o o
o o
Not Recommended.
For S1 units: 1 gpm/ft. =40.746 (L/min.)/m; 1 ft. =0.305 m; 1 ft. =0.0929 m ; 1 in. =0.0245 m; C = F - 32/1.8.2 2 2 2 o o
NumberRequired
HydrocarbonApplicationRates
DischargeTimes
PolarSolvents
SizeofTank
Hydrocarbon
ApplicationRates
DischargeTimes
NumberRequired
HydrocarbonApplicationRates
DischargeTimes
PolarSolvents
Fixed-Roof (Cone) Tanks Pontoon or Double-Deck Floating Roof Tanks
STORAGE TANK PROTECTION SUMMARY
65 min.50 min.65min.
30 min.
55 min.55 min.
D056rv0200
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
34/35
Numberof FoamOutletsRequired
HydrocarbonApplicationRates
PolarSolventRates
Fixed-Roof (Cone)Tanks andPan-TypeFloating Roof Tanks
Pontoon or Double-Deck FloatingRoof Tanks, (Open-Top or
Covered) Annular Seal Area
STORAGE TANK PROTECTION SUMMARY
Up to 80 ft. (2.44 m) dia.81to 120ft. (24.7 - 36.6 m) dia.121 to 140 ft. (36.9 - 42.7 m) dia.141 to 160 ft. (43 - 48.8 m) dia.161 to 180 ft. (49 - 54.9 m) dia.181 to 200 ft. (55.2 - 61m) dia.Over 210 ft. (61.2 m)
1 Foam Chamber2 Foam Chambers3 Foam Chambers4 Foam Chambers5 Foam Chambers6 Foam Chambers1 additional for each
5,000sq. ft.
1 for each 40 ft. (12.2 m) of circumferencewith a 12-inch (30.5 cm) high foam dam.
1 for each 80 ft. (24.4 m) of circumferencewitha 24-inch (61 cm) high foamdam.
0.10 gpm (0.38 L/min.) per sq. ft. (sq. m) ofliquid surface. 0.30gpm (1.14 L/min.) per sq. ft. (sq. m)of annular ring area between tank walland foam dam.
Not covered byNFP A 11.See Manufacturer's Approval Report.
Flash Pt. 100 F - 140 F (37.8 C - 194.4 C)Flash Pt. below 100 F (37.8 C)Crude Petroleum
o o o o
o o
Type I
20 min.30 min.30 min.
Type II
30 min.55 min.55 min.
20 min.
Type IType II
30 min.55 min.
Not covered byNFP A 11.
HydrocarbonDischarge
Times
PolarSolvents
D057rv195
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
7/28/2019 Storage Tank Systems[1]
35/35
Engr. Salman Ali SyedSEC-SOA, Abha
KSA.
Recommended