aircraft hangars design

AIRCRAFT HANGAR FIREPROTECTION

Foam 430aMarch 1, 2001

APPLICATIONDESIGN DATA

Form No. 062793 Replaces pages 950a-h dated February 28, 1994 and940i-k dated August 26, 1994. Revised page number.

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GENERALA fixed foam/water fire protection sys-tem is essentially the most effectivemethod of protecting aircraft hangars to-day. As the aircraft industry has ex-panded, aircraft values have increasedtremendously, to better serve the indus-try. Consequently, properly designedand installed foam/water fire protectionsystems are very important when con-sidering the overall aircraft hangar de-sign. References are made to variousprotection standards in this Design sec-tion, and users are cautioned to becometotally familiar with these standards, be-fore attempting to develop a properly de-signed aircraft hangar foam/water fireprotection system. At the very least, theuser must be familiar with various Na-tional Fire Protection Association(NFPA) pamphlets such as NFPA 11,13, 16, 16A, 22, 24, 30, 409, 419, insur-ance company standards,and/or othercorresponding standards includingLPC,VdS, or other applicable stan-dards/codes required by the AuthorityHaving Jurisdiction.

WARNINGThe information contained in this sectionis intended to be used in conjunctionwith the above mentioned standards, aswell as other required standards. It is notto be used as a “stand alone” designguide, under any circumstances. Thetechnical information ,statements andrecommendations contained in thismanual are based on information andtests which, to the best of our knowl-edge, we believe to be dependable. Itrepresents general guidelines only, andthe accuracy or completeness thereof,are not guaranteed since conditions ofhandling and usage are outside our con-trol. The purchaser should determinethe suitability of the product and/or infor-mation for its intended use and assumesall risks and liability whatsoever in con-nection therewith.

DEFINING THE TYPE OR “GROUP”OF AIRCRAFT HANGARThe classification or “grouping” of air-craft hangars in accordance with their

design and construction as shown be-low, makes it possible to determine howthe hangar is to be protected. Essen-tially, according to NFPA 409, there arethree different classifications or “groups”of aircraft hangars, each with its own in-dividual features or operating conditionswhich describe or differentiate onegroup from the other. The following defi-nitions and/or tables describing thethree different groups of aircraft hangerswere taken from the 1990 edition ofNFPA 409.

GROUP I AIRCRAFT HANGAR. A han-gar having at least one of the followingfeatures and operating conditions:

(a) An aircraft access door heightover 28 ft (8,5m)

(b) A single fire area in excess of40,000 sq ft (3716m)

(c) Provision of housing for an air-craft with a tail height over 28ft(8.5m)

(d) Provision of housing for strategi-cally important military aircraft asdetermined by the Department ofDefense.

GROUP II AIRCRAFT HANGAR. Ahangar having both of the following fea-tures:

(a) An aircraft access door height of28 ft(8.5m) or less;

and(b) A single fire area for specific

types of construction in accor-dance with Figure 1 for Group IIAircraft Hangars:

GROUP III AIRCRAFT HANGAR. AGroup III hangar may be a freestandingunit for a single aircraft, a row hangarhaving a common structural wall androof system and housing multiple aircraftas well as having door openings for eachaircraft, and have both of the followingfeatures:

(a) An aircraft access door height of28 ft (8.5M) or less ;

and(b) A single fire area that measures

up to the maximum square foot-age permitted for specific typesof construction in accordancewith Figure 2 for Group III AircraftHangars:

AIRCRAFT HANGARFOAM/WATER

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March 1, 2001Foam 430b

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GROUP I AIRCRAFT HANGARPROTECTION

The main objective of the fire protectionsystem is to protect the hangar alongwith the aircraft, should there be a flam-mable liquid (fuel) spill. This is the main

reason , therefore, why a deluge type offoam/water system is necessary. NFPAPamphlet 409 “Aircraft Hangars”, statesthat “a Group I aircraft hangar storageand service area shall be equipped withan approved automatic foam/water de-luge system - as the primary system.”Therefore, a Group I hangar will have

overhead deluge foam/water systemswith a maximum of 15,000 sq ft (1394m2) of floor area coverage per system,as the primary protection system. How-ever, should the wing area of the aircraftexceed 3000 sq ft (279m2), a secondaryunder-wing foam/water monitor systemis also required. An under-wingfoam/water system may also be re-quired if there are multiple aircraft beingstored in the hangar, even though thewing areas are less than 3000sq ft(279m2) each, so consult with the Au-thority(s) Having Jurisdiction if there isany doubt regarding the supplemntarysystem. The supplementary under-wingsystem’s objective is to control the firewithin 30 seconds, and to extinguish itwithin 60 seconds. NOTE: If the fueltanks of the aircraft being housed in thehangar are purged and drained, then theabove requirements for roof and un-der-wing protection “Do not apply to air-craft storage and servicing areas.” How-ever, automatic closed-head sprinklerprotection is still required “inside sepa-rate shop, office and storage areas lo-cated inside aircraft maintenance andservice areas, unless they are otherwiseprovided with automatic fire protectionsystems”, per NFPA 409.

There are several methods of providingfoam to the roof and monitor systemsusing Viking equipment, and most ofthem have already been previously indi-cated in the Design section of this Databook. They include Viking deluge sys-tems, as well as Viking pressure regulat-ing systems. The Viking pressure regu-lating systems are unique, in that theyutilize bladder tank systems and In LineBalanced Proportioners (ILBP’s), whicheliminate the installation of foam con-centrate pumps. For more detailed in-formation on the pressure regulatingsystem, you should refer to the propersection of this Data Book,as well as theViking Engineering And Design DataBook. NFPA 409 states that the “controlvalves, foam liquid concentrate storage,injection system, and foam concentratepump shall be located outside aircraftstorage and servicing areas. The envi-


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Foam 430cMarch 1, 2001

Once the hangar group has been defined, design parameters may be establishedand preliminary system foam quantities can then be calculated, along with themethod of foam delivery, backup systems, and other system components. Figure3 can be used as a means of determining the overall fire protection design re-quirements for an aircraft hangar.

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March 1, 2001Foam 430d

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ronmental conditions shall be suitablefor the particular agent involved.”Therefore, careful consideration mustbe given to the location of the foamtanks, system risers, and associatedequipment, in relation to the aircraft han-gar storage and service areas.The following chart is a general review ofType I aircraft hangar fire protection de-sign, based on using criteria from the1990 edition of NFPA 409. It is intendedto be used only as a guide, and in con-junction with the aircraft hangar designpamphlets, insurance company rules,governmental regulations and require-ments, and other standards required bythe authorities having jurisdiction, whendeveloping the hangar’s fire protectionsystem.The following example is intended to fa-miliarize the user with how to determinethe fire protection design for a Group Ihangar. It is to be used only as a guide tohelp develop the overall fire protectionsystem requirements for a Group I air-craft hangar. It is not intended to beused as a stand alone design guide,since the actual project specifications,building codes, and other project re-quirements, must be used to determinethe actual aircraft hangar design.

STEP 1- CLASSIFY HANGARThe hangar classification for this par-ticular example has already beenpre-determined to be a Class I han-gar. If the hangar classification wasnot known, the previously illustratedtables would be used as a reference,in order to determine the aircraft han-gar classification, along with the pro-ject documents and requirements ofthe authorities having jurisdiction.

STEP 2- REVIEW PROJECT REQUIRE-MENTSANDPROTECTIONOPTIONSThis example of a Group I hangar is240 ft (73.15m) long, and 275 ft(83.8m) wide, and it houses a 747type aircraft. It also has a 60 ft(18.3m) x 50 ft (15.2m), 3000 sq. ft.(278.7m) addition at the front end ofthe building, in order to enclose theaircraft’s nose section. (See Figure5)

STEP3-SELECT TYPEOFFOAM,DETER-MINE PRIMARY (ROOF) SYSTEM DIS-

CHARGE DENSITY AND DURATIONIn order to determine the proper roofsystem density, the exact type offoam concentrate must be known(I.E. AFFF, fluoroprotein, protein),since it directly affects the roof den-sity. For this particular example,AFFF foam will be used, along withstandard sprinklers. Therefore, aroof density of .16 gpm (6,5 l/m/m),for a minimum duration of ten min-utes is required by NFPA 409.

NOTE: If an aspirated AFFF,fluoroprotein or protein type of foamconcentrate was to be used in lieu ofthe AFFF concentrate as demon-strated above, then the roof systemdensity would have been .2 gpm/ sq ft(8.1 l/m/m). This would then affectthe capacity of the foam concentratestorage tanks, the on site water stor-age tank capacity, fire pump sizing,and other related system compo-nents such as system pipe sizing.So, selecting the proper foam con-centrate may save some unneces-sary project costs. However, the se-lected foam concentrate must stillmeet the project requirements,codes, and other AHJ require-ments.For example, a foam concen-trate such as milspec AFFF, (militaryspecification AFFF), could be speci-fied for a non-military project, but itmight not actually be required toproperly protect the hazard. Use ex-treme caution when designing or bid-ding on projects such as this, by al-ways stating exactly what is or is notincluded.

STEP 4- CALCULATE THE PRIMARY(ROOF SYSTEM) FOAM QUANTITYThe primary foam quantity is deter-mined by the following formula:Q = D x A x 1.15 x T x P

where:Q=Quantity of foam in gallons or li-ters D=Density in gpm/sq ft or l/m/m2

A=Area of application in sq ft or m2

1.15=15% overage factor(this is themaximum system overage allowedby NFPA 409)T=Time of discharge (normally 10minutes, but check actual job re-quirements. Don’t forget about con-nected reserve supply which mayalso be required.P=Percentage of foam concentrate.(Usually 3%, but is subject to actualproject requirements.)Q = .16gpm x 69,000 sq ft x 1.15 x 10

minutes x 3%Q = .16 x 69,000 x 1.15 x 10 x .03Q = 3808.8 gallons (14417,9 liters) ofAFFF foam concentrate for the roofsystem.

NOTE: This example only covers the ini-tial 10 minute duration. Should a re-serve be required, then it must beadded to the original “Q” above. Thiswill also affect the capacity of thefoam conentrate bladder tank(s) orstorage tank(s).

NOTE: STEPS 5, 6, & 7, ARE ONLYREQUIRED FOR HANGARSHOUSING AIRCRAFT WITH WINGAREAS LARGER THAN 3000 SQFT (279M), OR IF REQUIRED BYTHE AHJ OR PROJECT DOCU-MENTS.

STEP 5- DETERMINE MONITOR LOCA-TION AND COVERAGE, IF WINGAREA EXCEEDS3000SQFT(279M)Determine supplementary monitorlocations and coverages for aircraftwith wing areas in excess of 3000 sqft (279m). Again, some projects mayrequire supplementary monitor sys-tems even if the aircraft wing areasare less than 3000 sq ft, refer to theproject documents for specific re-quirements.

NOTE: The arc of coverage under thewings of the aircraft and beyond, aswell as the monitor nozzle “throw”and coverage under the fuselage,are usually described in the bid docu-ments and also indicated on the con-tract drawings. Otherwise, you mustconsult with the specified monitornozzle manufacturers for specificmonitor nozzle station information, orany other questions related to moni-tor system design, in order to prop-erly design the supplementary under-wing fire protection system. The de-sign objective of the supplementaryunderwing system, according toNFPA 409, is to achieve control of thefire within 30 seconds, and to extin-guish the fire within 60 seconds. It isimportant to note at this point, that theplacement of monitor nozzles, alongwith the areas of coverage, flows,nozzle settings and related informa-tion, may vary on each aircraft han-gar project due to owner/architectpreference.Because of all the variables involvedwith the selection of monitor nozzlestations, it is not possible to providethe contractor, engineer or designer


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with a detailed step by step set of in-structions on how to design the moni-tor nozzle stations. Usually, asstated earlier, the documents and orplans will indicate the approximateplacement of the monitor nozzle sta-tions, along with the areas of cover-age for each station. If this informa-tion is not available, it is imperativethat it be requested, in writing, beforeproceeding with bidding the project.Contacting the monitor designingnozzle manufacturer(s) for additionalinformation is also suggested.Viking has attempted to be as spe-cific as is possible with aircraft han-gar design, however, monitor nozzlestation placement is something thatthe owner or engineer has a greatdeal of input on, and it is best to con-sult with them, should any questionsarise. Should there be a question onthe monitor nozzle selection, or if anydoubt exists as to whether the equip-ment specified is correct for the par-ticular application, it is imperativethat a letter be written to the author-ity(s) having jurisdiction, asking forclarification, or requesting instruc-tions as to how to proceed in orderingthe monitor nozzle station equip-ment. This will avoid the possibility ofordering equipment which is not com-patible or is not desired for use on theproject.Should questions arise which are notcovered by NFPA 409, and/or othersimilar pertinent design standards,Viking will assist the contractor withresolving the questions by attemptingto obtain official interpretations of thestandards. All of the official interpre-tations which we receive, will be doc-umented for future reference.For this particular example, a total offour monitors were required, two atthe ends of the wings, and one ateach side of the fuselage, just behindthe nose of the aircraft. This place-ment, selected by the owner alongwith the project engineer, allowed forthe desired underwing and fuselagecoverages, with minimal floor spacerequirements. The monitor nozzlechosen, was selected for proper“throw”, in order to force a possiblefuel spill out from under the body andwing area of the aircraft.

STEP6-DETERMINEMONITORSYSTEMAPPLICATION RATE AND DURATIONThe minimum supplementary moni-

tor system application rate requiredby NFPA 409 for an AFFF system, is0.10 gpm of foam solution per sq ft(4,1 l/m/m) of floor area beneath thewing and wing-center section of theaircraft. For protein or fluoroproteinbased concentrates, the minimumapplication rate required is 0.16 gpmof foam solution per sq ft (6,5 l/m/m)of floor area beneath the wing andwing-center section of the aircraft.Since this particular example isbased on using AFFF foam, the mini-mum density for the supplementarysystem is 0.10 gpm/sq ft (4,1 l/m/m).The minimum duration required byNFPA 409 is 10 minutes.

STEP 7- CALCULATE FOAM QUAN-TITY FOR MONITOR SYSTEMThis is accomplished in essentiallythe same manner as described inStep 4, or (Q = D x A x T x P). How-ever, the monitor nozzle pressure,and the minimum monitor nozzle flowrequired to achieve the desired noz-zle coverage, must be factored intothe above formula, or the “Q” may beseverely underestimated, resulting inextra project costs. The area of un-der-wing coverage in this example,for each of the four monitor nozzles,calculates out to approximately 1375sq ft (127,75 m), (5500 sq ft 4 moni-tor nozzle locations = 1375 sq ft perlocation). (Estimated monitor nozzleflow = 0.1 gpm x 1375 sq ft, or 137.5gpm per station). However, eachmonitor nozzle oscillates over a pre-scribed area of coverage, and mayinclude overlapping spray patterns,so the actual nozzle flow must be de-termined from the actual arc of oscil-lation. The actual area (A) for the arcof oscillation (AO) may be deter-mined by using the following formula:(Our example has a 35°AO, and a“throw” (r) of 125’ (38,1m)A = (�r)(AO� 360°) where r = radiusof monitor nozzle “throw”A = (3.14 x 125) x (35° � 360)A = (49062.5) X 0.097A = 4770 sq ft (443,1 m) x .1 gpmunderwing densityThis results in a minimum monitornozzle flow of 477 gpm (1805,6 l/m).For practical purposes, the monitornozzles should be considered asflowing 500 gpm (1892.7 lpm) each,as 500 gpm is a tested monitor noz-zle rating. Now that the total flow permonitor station has been determined

(4 stations total), the amount of foamconcentrate (Q) can be calculated.

NOTE: There may be some instanceswhen it is permissable to eliminatethe area included in the arc of oscilla-tion (AO) from the monitor nozzle to apoint where the foam solution first be-gins to strike the floor, from the abovecalculation. The area will vary de-pending upon the angle of elevationof the monitor nozzle, along withother factors such as the manufac-turer, adjustability of the nozzle, andsystem pressure. Therefore, it is im-perative that the authority having ju-risdiction be consulted for a final de-termination.To find the amount of foam concen-trate (Q) required to provide the de-sired percentage of foam concen-trate in the foam/water solution, forthe monitor stations, use the follow-ing formula:Q = (F) x (N) x (T) x (P), where F is theindividual monitor nozzle flow, N isthe number of monitor stations re-quired, T is the time of discharge, andP is the percentage of foam concen-trate required in the foam/water solu-tion. Therefore:Q = F x N x T x PQ = 500 gpm x 4 stations x 10 min-utes x 3% solutionQ = 500 x 4 x 10 x .03Q = 600 gallons (2271,3 liters) offoam concentrate

STEP 8- CALCULATE THE HANDHOSE LINE REQUIREMENTSThe project documents must be re-ferred to, in order to determine thenumber of hand hose lines which willbe required to operate, and theamount of flow each station is re-quired to provide. For this example,the requirements of NFPA 409 mustbe met, so this means that 2 handhose lines will be in operation, andeach will flow 60 gpm (227 l/m) for aperiod of 20 minutes.

STEP 9- CALCULATE FOAM QUAN-TITY FOR HAND HOSE LINESUse a modified version of the originalformula to calculate the amount offoam concentrate (Q) required to op-erate the hand hose stations for therequired amount of time. The modi-fied formula will be: Q = F x N x T x P,where (F) represents the hose stationflow, (N) stands for the number ofhand hose stations required to oper-


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ate, (T) represents time of operation(20 minutes per NFPA 409), and (P)is the percentage of foam concen-trate required in the foam/water solu-tion. Therefore:Q = F x N x T x PQ = 60 gpm x 2 stations x 20 minutesx 3% concentrateQ = 60 x 2 x 20 x .03Q = 72 gallons (272,6 liters) of foamconcentrate

STEP 10- CALCULATE TOTAL QUAN-TITY OF FOAMThe total quantity of foam can now bedetermined by simply adding thesub-totals from Steps 4, 7 and 9 to-gether.Total “Q” from Step 4 = 3808.8 gal-lons of foam concentrateTotal “Q” from Step 7 = 600.0 gallonsof foam concentrateTotal “Q” from Step 9 = 72.0 gallonsof foam concentrateTotal “Q” of 4480.8 gallons (16961,7liters) of foam concentrate will be re-quired for this projectThe total quantity of foam may bestored in a single or multiplereser-voiirs or tanks such as Vikingbladder tanks, depending on the typeof foam discharge devices selected.The Authority Having Jurisdictionshould also be consulted as to howand where the bladder tanks, monitornozzle foam reservoirs, and relatedfoam storage may be located.

NOTE: The above quantity of 4480.8gallons ( 16961,7 liters) of foam con-centrate is the minimum requirementby NFPA 409. It does not include anyreserve amount of concentrate whichmay be required by the project docu-ments or additional demands whichmay be required by the insuring body,LPC, Vds or any other Authority Hav-ing Jurisdiction.

STEP 11- REVIEW STEPS 1THROUGH 10 FOR COMPLIANCEThe reason that this step was in-cluded, was simply to alert the de-signer(s), engineer(s), or other par-ties involved in the design of the air-craft hangar fire protection system,that a review of the project should beperformed at this time. This would in-clude reviewing the project drawings,documents and other related mate-rial, checking the information con-tained in this data book, such as thereview of the type I hangar fire protec-

tion table, and any other related doc-uments, such as NFPA 409. Thisstep should also be used to dou-ble-check for any items which mayhave been previously overlooked, ordidn’t seem very important at the be-ginning of the project. It is a discre-tionary step, and is totally up to theperson(s) involved with the project todecide how detailed the review is tobe.

STEP 12- COMPLETE A PRELIMI-NARY LIST OF MATERIALEach project will have its own specificrequirements, so there will be varia-tions which differentiate one projectfrom another. The easiest method tofollow in order to complete a prelimi-nary list of materials for the Vikingfoam/water fire protection system in-stallation, is to utilize the Checklistfound in the “Miscellaneous” section,at the end of the Viking Foam Techni-cal Data Book. It is a step by stepchecklist of Viking’s foam/waterequipment including discharge de-vices, concentrate controllers, con-centrate control valves, types of sys-tems, and other related devices.The example included for this exer-cise, utilizes a Viking deluge valvewith a hydraulically actuated concen-trate control valve (a Viking Halarcoated deluge valve with propertrim), installed as indicated on Figure201, found on page 201b, in the Vi-king Foam Systems Engineering andDesign Data Book.

DETECTION SYSTEMSThere are many types of detectionsystems used to activate either theroof system or the supplementary un-der-wing system, such as a combina-tion of Ultra-Violet and Infra-Red(UVIR) detectors, heat detectors,smoke detectors (very seldom used),pilot sprinklers, rate of rise detec-tors,or beam detectors. On most air-craft hangar projects, the type of de-tection system will be indicated onthe construction plans, and in theproject documents. Electric detec-tion system layouts, including spe-cific detector locations, are usually in-dicated on the construction plans, es-pecially when some of the more so-phisticated types of detectors, suchas UVIR, or beam detectors arespecified.For most aircraft hangar projects, thepneumatic or hydraulic detection sys-

tem for the roof and supplementaryunderwing monitor nozzle system willbe included as part of the fire protec-tion specification. This is becausemost fire protection contractors whoare experienced in special hazardtype projects, such as aircraft hangarinstallations, are familiar with bothtypes of detection systems, alongwith their components. For specificinformation on Viking’s MicrofastModel M fixed temperature releases,Model C-1 thermostatic releases,and other pneumatic or hydraulic de-tection equipment, please refer to theViking Engineering and Design DataBook.Normally, an electric detection sys-tem would be included as part of theelectrical specifications, but therehave been occasions where even theelectrical detection has been in-cluded as part of the fire protectionsection. Should the project docu-ments require that the fire protectioncontractor provide an electric detec-tion system, it is suggested that thefire protection contractor subcontractthe entire detection system to a wellestablished electrical contractor whois familiar with similar detection sys-tem installations. The fire protectioncontractor may wish to exclude theelectrical detection portion of the pro-ject from his/her bid. Whatever theexception(s) or inclusion(s) to theproject may be, it is simply goodpractice to indicate them in writing, inorder to eliminate possible confusionor conflict.

APPROVALSOnly listed and/or approved valvesand devices should be used on air-craft hanger installations. This issimply good practice as it indicatesthat the valves and devices havebeen tested and/or approved fortheir intended use. The proper sprin-kler head(s) must be selected basedupon the type and brand of foam be-ing used.Viking has the most comprehensivelisting and approval of sprinklerheads for use with various types of3M foam in the industry.Viking sprinkler heads are also listedand approved with other brands andtypes of foam. Please refer to the ta-bles found in the “Discharge Devices”sub-section of this data book for acomplete listing of the Viking sprin-


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klers for use with various brands andtypes of foams.

This section of the Aircraft Hangar Pro-tection Application information, willcover Group II aircraft hangers, or thoseaircraft hangers which have both of thefollowing features:

(a) An aircraft access door height of28ft (8.5m) or less;

and(b) A single fire area for specific types

of construction in accordance withFigure 1, as indicated on pageFoam 430b.

Note: This section does not pertain toGroup II hangers housing aircraft withdrained and purged fuel tanks. (SeeNFPA Pamphlet 409, 1990 Edition, Sec-tion 4-1.1 for reference.)

Group II aircraft hangers must be pro-tected in accordance with any of the fol-lowing methods:

(a) The same requirements as thosedescribed for Group I aircrafthangers, except that the dischargerate for foam/water deluge sys-tems using air aspirating dis-charge devices, may be reducedto a minimum of 0.16 gpm/sq. ft. offoam solution (6.5l/min/m), forGroup II aircraft hangers.

(b) A combination of automatic sprin-kler protection as described in the“Sprinkler System” section ofGroup II Aircraft Hangar Protectionin NFPA 409, and an automatic,low level, low expansion foam sys-tem, as described in the “Low Ex-pansion Foam System” portion ofGroup II Aircraft Hangar Protec-tion.

(c) A combination of automatic sprin-kler protection, again as describedin the Sprinkler System section ofGroup II Aircraft Hangar Protec-tion, and an automatic high expan-sion foam system, as described inthe High Expansion portion of theGroup II Aircraft Hangar Protec-tion.

Along with the above requirements, au-tomatic closed-head sprinkler protectionmust be provided inside separate shop,

office, and storage areas located insideaircraft maintenance and servicing ar-eas. The design must be in accordancewith hazard classifications specified inNFPA 13, or other applicable standard.In addition to the requirements as de-scribed above, the hand hose,foam-water hand hose systems, andwheeled and portable extinguisher re-quirements for Group I aircraft hangers,also apply, as well as “Protection Sys-tem Alarms” described in NFPA 409, orother applicable standards.As with Group 1 Aircraft Hangars, thecontrol valves, foam-liquid concentratestorage, injection system and concen-trate pump (if required), must be locatedoutside the aircraft storage and servic-ing areas, and the environmental condi-tions must be suitable for the concen-trate being used. Therefore, it is impera-tive that careful consideration begiven to the location of the foam tanks,system risers, and associated equip-ment, in relation to the aircraft hangarstorage and service areas. The follow-ing chart contains a general review ofGroup ll hangar fire protection design,and it is to be used as a guide only, andin conjunction with recognized aircrafthangar protection standards, insurancecompany rules, governmental regula-tions and requirements, and other stan-dards required by the authorities havingjurisdiction.

ACCEPTANCE TESTSThe system(s) may be required to betested with the foam system in opera-tion, to insure that the system performsas required. This may mean a test of thefoam/water solution to check for properpercentage, such as 3% or 6%, etc.Proper disposal of the foam solution isessential to the acceptance test, and alllocal, state and other applicable stan-dards for proper disposal of thefoam/water solution, must be followed.The required standards will also statehow many systems must operate simul-taneously, so as to determine if the wa-ter supply is adequate,flow pressures,agent discharge capacity, foam cover-age, percentage of concentration, and

other operating characteristics are satis-factory.Once the acceptance tests have beencompleted, the installing company (con-tractor), may be required to furnish awritten statement that the work has beencompleted in accordance with the ap-proved plans and specifications, andproperly tested.

DETECTION AND ACTUATIONSeveral types of detection may be usedto actuate the high or low expansionfoam systems along with the pre-actionsprinkler system, and the most commonones are fixed temperature, rate com-pensated or rate-of-rise types. Pleaserefer to the manufacturer’s technicaldata for proper installation informationfor the detection system. Viking hasseveral types of detection systems avail-able such as fixed temperature re-leases, pilot sprinklers, and rate of risedetection (C-1 Thermostatic Releases).Please refer to the Viking Engineeringand Design Data Book for detection de-vices, spacing requirements, and otherrelated information. The use of rate ofrise detection in aircraft hangars mustbe very carefully considered, or false op-eration of the system could occur. Thedesigner must be familiar with how a rateof rise detection system operates, sinceoperation of the detection system can beaffected by varying annual weather con-ditions or conditions which could createa sudden rise in temperature. Detectionsystems may also be required to be pro-vided with complete supervision, asNFPA 409 requires. Manual actuationstations are required by NFPA 409, andthey must be located so that each sys-tem can be individually operated fromboth inside or outside the aircraft stor-age and servicing area. The manualstations must be located so as to be un-obstructed, readily accessible, and lo-cated in normal paths of exit from thearea. Again, it is imperative that the ap-plicable requirements be adhered to forthe proper design of the aircraft hangar’sfire protection system.

WATER SUPPLY

GROUP II AIRCRAFT HANGAR PROTECTION


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The water supply must be sufficient tosupply the combination of systems andhose stations as required by the applica-ble standard(s), for both quantity and du-ration. Group II aircraft hangars requirea minimum of 30 minutes of water at therequired rates called for in NFPA 409.The water supply for low expansionfoam systems in Group II aircraft han-gars must be capable of a 10 minute du-ration suitable for the production offoam. For high expansion foam sys-tems, the water supply duration must becapable of producing foam for 12 min-utes. The water supply must also be ca-pable of providing the hose stations asrequired by the standards being used,and if the system also serves as a supplyfor exterior hose streams, a minimum500 gpm (1893 l/m) must be included inthe calculations. If fire pumps and suc-tion reservoirs are provided, then theymust be designed and installed in accor-dance with the design standards whichapply to the specific project.

For most Group III aircraft hangars, nofixed system fire protection is neces-sary. However, where hazardous oper-ations including fuel transfer, welding,torch cutting, torch soldering, doping,and spray painting are performed, thehangar must be protected in the samemanner as a Group II facility, per NFPA409 requirements. Please check the ap-plicable standards for your specific pro-ject to find out what they may require forfire protection systems.

Portable fire extinguishers are also re-quired for Group III hangars, per NFPA10. When portable extinguishers arelocked up to prevent the possibility oftheft, each tenant and aircraft ownermust have a key for the locks. The distri-bution of fire extinguishers in the aircraftstorage and servicing areas, must be inaccordance with extra hazard classifica-tion as outlined in NFPA 10. In other ar-eas of the aircraft hangars, the distribu-tion of the extinguishers shall be in ac-cordance with light, ordinary or extrahazard occupancy, based upon an anal-ysis of each room or area following therequirements of NFPA 10, or other appli-cable standard(s).

PERIODIC INSPECTION ANDTESTING OF GROUP I, II & III AIR-CRAFT HANGARSAll Group I, II, & III aircraft hangar fireprotection systems, will require inspec-tion and testing at certain intervals. Theinspection and testing is to be performedaccording to the prevailing standard(s)for aircraft hangar sprinkler system in-spection and testing. For example,NFPA 409 contains a table for periodicinspection and testing (refer to Table6-1.1), which contains specific inspec-tion and test information along with thetimetables within which the inspectionsand tests must be completed. It is veryimportant to maintain all records of in-spections, tests, and test results, asproof that the system(s) have been in-spected and tested on a properly sched-uled basis.

Please note that this application infor-mation is essentially based on NFPA fireprotection system requirements. How-ever, there may be other overriding fireprotection system standards which ap-ply to specific projects, and these stan-dards may be much different than whatNFPA requires. This is the main reasonwhy this application information is not in-tended to be used as a “stand alone” de-sign guide, but rather in conjunction withall other applicable standards. This ap-plication information is intended to assistin the fire protection design of the aircrafthangar only, and it does not apply toother areas of aircraft hangar design,such as construction, internal separa-tions, clear space distances around han-gars, floors, roofs, drainage, heatingand ventilating, lightning and electrical,lighting, grounding, exit and access,draft curtains, etc.

(Note: For Group I, II, and III aircraft han-gars, please refer to NFPA 409, or thespecific project’s applicable standard(s),for specific requirements pertaining toAcceptance Tests, Wheeled and Porta-ble Extinguishers, and Protection Sys-tem Alarms, since these items are notcovered in detail in this application man-ual.)

The information included in the AircraftHangar Foam/Water Systems section ofthe Viking Foam Systems Engineeringand Design Data Book, is based on the1990 edition of NFPA 409. While Vikingwill make every effort to update this sec-tion in accordance with the latest NFPA


SYSTEMSDESIGN DATA

Foam 430kMarch 1, 2001

GROUP III AIRCRAFT HANGAR PROTECTION

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information, etc., it is the responsibility ofthe user/purchaser to determine thesuitability of the product and/or informa-tion for its intended use, and theuser/purchaser assumes all risks and li-abilities whatsoever in connection there-with.

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Form No. 062793 Replaces pages 950a-h dated February 28, 1994 and940i-k dated August 26, 1994. Revised page number.

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aircraft hangars design

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