trench drains parallel to the hangar bay doors and space them in-between with a spacing not to
exceed 50 feet (15.2 m) center-to-center. A trench perpendicular to these trenches may be
necessary to route the system piping. For "Pull-in" type hangars (see Figure 2), provide a trench
drain in the aircraft storage and servicing area located just inside and parallel to the hangar bay
door. Additional trench drains shall be provided perpendicular to the hangar bay door with
spacing between trench drains not exceeding 50 feet (15.2 m) center-to-center.
Trench drains shall be sized to account for the flow of the sprinkler system, AFFF
system discharge, hose stream allowance, the volume of the pipe, turning radius of the fittings,
and allow for maintenance.
Foam concentrate tanks, proportioning equipment and sprinkler control valves shall be
located in a room separate from the aircraft servicing area by a minimum of 1-hour fire resistive
construction. Flow control valves/proportioners may be located outside of this room in order to
minimize the AFFF delivery time to the hangar floor. Equipment rooms shall be configured or
sized to provide access for inspection, maintenance, and repair of all equipment. Doors
providing direct access to the exterior of the structure shall be provided. Equipment shall be
located to permit removal of tanks, bladders, valves, pumps, and motors without the removal of
If piping must be located below the floor line, use concrete trenching with steel
grating. Do not install any piping below a concrete slab. Avoid locating piping under paved
operational surfaces (taxiways and aircraft parking).
manufactured by Spectrex Inc. (SharpEye Triple IR (IR3) Optical Flame Detector (20/20I)), or
Det-Tronics (X3301 Multispectrum IR flame detector). The activation of any two triple IR
flame detectors shall activate the low-level AFFF fire suppression system.
The triple IR detectors shall be mounted approximately 8 feet (2.4 m) above the
finished floor of the hangar. The specifics for each facility must take into account facility
construction, type of aircraft, aircraft configuration and positioning, fixed and mobile equipment
within the aircraft servicing area, and all other relevant factors.
The optical flame detectors shall be installed with five feet (1.5 m) of flexible conduit
to allow for any minor adjustments during testing or changes in mission of the hangar.
All areas of the aircraft hangar floor shall be visible to a minimum of 3 optical flame
If a preaction sprinkler system is used, install 160F (71C) rate compensated type
heat detectors or thermistor type thermal detectors to activate the system. The detectors shall
utilize a spacing of 40 feet by 40 feet (12.2 m by 12.2 m) regardless of ceiling height, but shall
not exceed their listed spacing (for a ten foot ceiling) without consideration for reduction in
spacing. Operation of a single detector shall activate the deluge valve for the preaction sprinkler
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19 January 2005