ETL 1110-3-484
26 Sep 97
AIRCRAFT HANGAR FIRE PROTECTION SYSTEMS
1. GENERAL. Fire protection systems are provided in aircraft hangars for protection against a
potentially devastating fire and the loss of valuable military assets. Current state-of-the-art
protection systems utilize aqueous film-forming foam (AFFF) to combat fuel spill fires that can
occur in facilities housing fueled aircraft. Because of the critical nature and the inherent
complexity associated with foam fire protection systems, it is essential that they be designed and
installed by those with the required expertise and experience. Lessons learned have identified
numerous installation and operational problems that can adversely affect system adequacy,
reliability and maintainability. It is therefore imperative that attention be directed to the design
and installation of these systems. The focus of this ETL is on design. Since there is a correlation
between the adequacy of the design and the acceptability of the final installation, emphasis must
be placed on producing designs that are technically correct and comply with applicable design
criteria. To better assure system acceptability, it is essential to thoroughly and clearly define
system requirements. This ETL establishes a number of procedures and technical direction to
assist designers in achieving this objective.
2. DESIGNER REQUIREMENTS. Design of foam-water sprinkler systems for aircraft
hangars requires specialized design knowledge and expertise. To assure adequacy of design, it is
essential that such systems be designed and specified by engineers with extensive experience in
this specialized area of fire protection system design. This is mandatory for Air Force projects
covered by Air Force ETL 96-1, Fire Protection Engineering Criteria-New Aircraft Facilities.
3. SUBMITTALS. Each design submittal stage should address crucial considerations affecting
the fire protection system design. This includes water supply systems, proposed types of sprinkler
and nozzle systems, foam concentrate proportioning systems, fire detection and controls systems,
etc. Of particular importance is the water supply system which must meet system demands.
Lessons learned indicate the need for more comprehensive water demand and water supply
analyses. After the initial design submittal, each succeeding submittal should be a further
elaboration and refinement of what was previously submitted. For example, whereas the concept
submittal may include only rough approximations of system water demand, the intermediate
(preliminary) and final submittals need to include detailed hydraulic calculations to confirm that
calculated system demands can in fact be met with the existing or proposed water system. This
analysis should be correlated with the design to provide substantiation of pump selection, pipe
sizes, nozzle selection, sprinkler discharges, etc. Specific requirements for design analysis,
drawings and hydraulic calculations are described later in this document.
4. TECHNICAL CENTER OF EXPERTISE (TCX). A TCX for Aircraft Hangar Fire
Protection was established to provide technical assistance to those involved in the design,
installation, and testing of aircraft hangar foam fire suppression systems. The TCX will provide,
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