Supplementary low-level (under-wing) AFFF nozzles shall deliver a foam
solution density of not less than 0.10 gallon per minute per square foot of
floor area beneath the aircraft. These systems shall be designed in
accordance with NFPA 409. Supplementary low-level (under-wing) fixed AFFF
nozzle systems shall be provided for the following:
a) Hangars which accommodate aircraft whose wing area is greater
than 3,000 square feet.
b) Hangars which may accommodate multiple small aircraft (of high
monetary value) in a close or tight configuration.
188.8.131.52 Helicopter Hangars. Helicopter hangars will not normally require
supplementary low-level AFFF systems.
Activation of Foam-Water Sprinkler Systems and Supplementary Low-
Level (Under-Wing) Fixed AFFF Systems. Activation of a single overhead
thermal rate-compensated heat detector, a single manual pull station or a
single optical detector shall cause activation of supplementary low-level
under-wing systems and pre-action foam-water sprinkler systems. In addition,
activation of any foam-water sprinkler system shall activate the supplementary
low-level protection systems.
For Army and Air Force projects, optical detection shall not
cause the activation of any fire suppression systems.
184.108.40.206 Manual Release Stations. Provide manual release stations for
activation of pre-action foam-water sprinkler systems and supplementary low-
level under-wing systems. Manual pull stations and manual release stations
shall be waterproof and protected from accidental activation. Manual release
stations shall be distinctively identified from the manual pull stations
associated with the fire alarm evacuation system.
220.127.116.11 Rate Compensated Heat Detectors. Provide "spot-type" rate-
compensated heat detectors at the ceiling level where pre-action foam-water
sprinkler systems are installed. Rate compensated heat detectors shall be
hermetically sealed. Install detectors to provide a maximum coverage of 400
square feet per detector. Detectors shall have a temperature rating not lower
than 190 degrees F.
18.104.22.168 Ultraviolet and Infrared Optical Detectors. Provide combination
ultraviolet and infrared optical detectors for low-level detection.
Water Supplies. The total water supply shall be capable of
furnishing water for the largest number of systems that may be expected to
operate. This shall include overhead foam-water sprinkler systems and
supplementary fixed under-wing protection systems. For overhead foam-water
sprinkler systems, calculate the water supply by assuming that a fire at any
point will operate all the systems (i.e., every sprinkler head on that system)