ETL 1110-3-485
15 Oct 97
3.13.4 Portable fire extinguishers will be provided in accordance with NFPA 10, Portable Fire
Extinguishers. Wheeled extinguishers employing potassium bicarbonate dry chemical are
generally recommended for helicopter hangar bays because they provide the maximum
extinguishing capability for Classes B and C type fires.
4. SPRINKLER PROTECTION FOR HANGAR BAYS
4.1 System Types.
4.1.1 Sprinkler systems will be closed-head type. Deluge (open-head) systems will not be used.
4.1.2 Systems will be foam-water type using AFFF unless conditions specified herein can be met
to permit water-only wet-pipe systems using ESFR sprinklers.
4.1.3 Although foam-water sprinkler systems using AFFF generally provide optimum
effectiveness in combating a combustible or flammable liquid spill fire, water-only systems using
ESFR sprinklers are considered to be an acceptable alternative.
4.2 System Selection.
4.2.1. The following guidelines for selecting the type of system to be used in helicopter hangar
bays are based upon the presumption that heating systems will be provided where required to
preclude freezing of pipes during winter months.
4.2.1.1 In geographic areas having a 99% dry bulb temperature greater than -10 oC (15 oF), wet-
pipe sprinkler systems will be used.
4.2.1.2 In geographic areas having a 99% dry bulb temperature between -18 oC (0 oF) and -10 oC
(15 oF), either wet-pipe or preaction system may be used. Selection of system type will be based
upon local factors that can affect potential for freezing of wet-pipe systems.
4.2.1.3 In geographic areas having a 99% dry bulb temperature of less than -18 oC (0 oF),
sprinkler systems will be preaction type using AFFF foam-water solution.
4.3 Foam-Water Sprinkler Systems.
4.3.1 Except as modified herein, foam-water sprinkler systems will comply with applicable
provisions of ETL 1110-3-484, Aircraft Hangar Fire Protection Systems, for detailed
requirements for foam-water sprinkler systems.
4.3.2 Foam-water sprinkler systems will be either wet-pipe or preaction type.
B-4
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