Post on 27-Jun-2015
NFPA 409: 2001Standard on Aircraft Hangars
A comparison of Foam SystemsJuly 11, 2002
Alison Wakelin
Presentation Contents
Structure of NFPA 409Classification of HangarsGroup I & II Construction RequirementsGroup I Hangar Protection Systems New Design OptionsGroup II Hangar Protection SystemsGroup III & IV Requirements
NFPA 409 Structure
Chapter 4 – Hangar ClassificationChapter 5 – Group I & II Building RequirementsChapter 6 – Group I Protection (major revisions 2001)Chapter 7 – Group II Protection
NFPA 409 Structure
Chapter 8 – Group III RequirementsChapter 9 – Group IV RequirementsChapter 10 – Periodic Inspection & Testing
NFPA 409 Chapter 4
Aircraft Hangar Groups
Hangar Classifications
Group I, either:Door height or aircraft with tail height > 28’ (8.5 m); orSingle fire area > 40,000 ft2 (3,716 m2)
Group II:Door height < 28’ (8.5 m); ANDFire area limits for construction types meeting Table 4.1.2.
Hangar Classifications
Group III:Door height < 28’ (8.5 m); ANDFire area limits for construction types meeting Table 4.1.3.
Group IV:Membrane covered, rigid, steel frame.
NFPA 409 – Chapter 5
Construction of Group I and Group II Aircraft Hangars
Group I & II Construction Highlights
Group I – Type I or II constructionGroup II – Type I through V construction depending on hangar areaInternal Separations:
Between aircraft hangar bays 3-hour Between hangar bay and service area 1-hourService areas between hangar bays –1 wall 3-hours and 1 wall 1-hour
Group I & II Internal Fire Separations
1-hour1-hour 1-hour 1-hour
3-hour3-hour
3-hour
1-hour
Hangar 1 Hangar 2 Hangar 3 Hangar 4
Office and Shop Area Office and Shop Area
Offi
ce a
nd S
hop
Area
Group I & II Construction Highlights
Main steel columns in the hangar shall have 2-hour fire resistance rating or column sprinkler protectionTrench drains
required to restrict spread of fuel and reduce fire and explosion hazardsystem designed and constructed to prevent build up of flammable liquids over the drain inlet with all fire protection systems dischargingWhere do they discharge to?
Group I & II Construction Highlights
Landing Gear Pits, Ducts, and TunnelsVentilation system utilizing flammable vapor detectionElectrical equipment suitable for hazardous locationsPressure venting or explosion protection
Ceiling Draft Curtains divide sprinkler systems into areas not greater than 700 m2
NFPA 409 – Chapter 6
Protection of Group I Aircraft Hangars
Existing Group I Protection Systems
NFPA 409 - 1995 editionFor Group I hangars a single option for the suppression system:
Overhead foam water deluge system (primary foam supply), with aSupplementary system to protect shadow areas under large wing areas (secondary foam supply)
New Group I Protection Options
Two new design options in 2001 editionExchange the roles of the fire protection systemsLow level system becomes the primary system supplying foam to the hangar floorOverhead sprinkler becomes the secondary system to prevent structural collapse of the building, wet adjacent aircraft, etc
New Group I Protection Options
NFPA 409 - 2001 editionFor Group I hangars two additional options were added:
Overhead Closed head wet pipe overhead sprinkler system, with aLow level foam system to provide complete coverage of floor area with foam using either:
• Low-level low expansion foam system, or• Low-level high expansion foam system
Option 1 Features
An overhead foam water deluge sprinkler system
Coverage area using 100-ft radius ruleSupplementary foam system for under the shadow areas of large wing aircraft
Monitor nozzles
Typical System Plan
Option 2 Features
Low-level AFFF deluge system covering entire floor area to within 1.5m of the hangar walls Trench or monitor nozzlesAn overhead closed head wet pipe sprinkler system using quick response sprinklers
Design area 15,000 ft2
Grate Nozzle Installation
Low-level AFFF Discharge
Option 3 Features
Low-level hi-ex foam deluge system covering entire floor area to within 1.5m of the hangar wallsCeiling or wall mounted hi-ex foam generators are used to provide foam
Outside air requiredAn overhead closed head wet pipe sprinkler system using quick response sprinklers
Design area 15,000 ft2
Sidewall Hi-ex Foam Generator
Start of Hi-ex Discharge
Hi-ex Foam 1-m Depth
Which Option?
Best option depends very much on combination of factors:
Site conditions such as water supply;Type of aircraft;The area of the hangar bay;Is the building new or existing;Costs;Maintenance.
NFPA 409 – Chapter 7
Protection of Group II Aircraft Hangars
Group II Protection Options
There are 4 design options:The 3 options for Group I hangars
Design area closed head sprinkler system reduced to 5,000 ft2
A closed-head foam-water sprinkler system
Design area is the entire hangar bay
NFPA 409 – Chapter 8
Group III Aircraft Hangars
Group III Requirements
All requirements for this group are contained in chapter 8Construction limits
Floor area limited for the construction typeFixed protection portable extinguishers
Unless hazardous operations including fuel transfer, welding, spray painting, etcHazardous operations = Group II hangar
NFPA 409 – Chapter 9
Group IV Aircraft Hangars
Group IV Requirements
Membrane flammability limitsFire separation of office and shop areasLanding gear Pits, Ducts and TunnelsFire Protection Systems:
All hangars shall have low-level foam system, andHangars with floor area > 12,000 ft2 shall have wet pipe sprinkler system (5,000 ft2 design area)
Group I Hangar Water Supply Requirements
Sprinkler System Foam System Total [gpm, liters]
Deluge O/H, Supplementary U/W AFFF
75,000 x 0.16 x 1.2 = 14,400 gpm
90 ft by 200 ft U/W area # = 90 x 200 x 0.1 = 1,800 gpm
16,200 gpm 61, 330 l
Wet Pipe O/H, LL AFFF (grate nozzle)
15,000 x 0.17 x 1.2 = 3,060 gpm
96 nozzles @ 152 gpm = 15,000 gpm
18,060 gpm 68,370 l
Wet Pipe O/H, LL Hi-ex
15,000 x 0.17 x 1.2 = 3,060 gpm
26 generators* @ 60 psi 26 x 220 = 5,720 gpm
8,780 gpm 33,240 l
All scenarios based on 300 ft by 400 ft hangar bay # Based on single large wing aircraft eg Boeing 747-400, multiple aircraft and parking positions lead to much larger area requiring coverage * Application rate (3 cfm/ft2) x hangar area + sprinkler breakdown factor (NFPA 11A) = 3 (300 x 400) + 10 (15,000 x 0.17) = 385,500 cfm Using 15,000 cfm hi-ex generators require total of 26 generators
Any questions?