The Naval Facilities Engineering Command (NAVFAC) has introduced a new low level, low expansion foam discharge nozzle for the protection of military aircraft hangars. The invention of this new in-floor Grate Nozzle technology was a joint effort between NAVFAC, Naval Air Systems Command (NAVAIR), and the Naval Research Laboratory and private sector firms Viking Corp. and Underwriters Laboratory, among others. AR Utility Specialists, Inc. (ARUSI), a Phoenix, AZ, design-build engineering firm specializing in design, construction management, fire protection and environmental services, has successfully completed the installation and final testing of this advanced fire protection system. This is the first design-build retrofit and installation using this kind of technology in the Southwest United States.

The Navy expressed interest in new fire protection technology that minimizes collateral damage to aircraft and equipment. In cooperation with Viking Corp., NAVFAC supported the design and development of a new evolutionary technology called the Grate Nozzle. The Grate Nozzle is specifically designed for protection of aircraft hangars. The Grate Nozzle is a foam/water solution discharge device located in trench drains at the floor level of an aircraft hangar. Unlike traditional fire protection systems, the Grate Nozzles use a flush-mounted system, have no moving parts and eliminate the need for fixed oscillating monitors and other devices that take up valuable floor space and are easily obstructed.

The Department of Navy-Naval Facilities Engineering Command (NAVFAC), Southwest Division, in San Diego, selected ARUSI as the design-build prime contractor to install the advanced fire protection system for the Naval Air Weapons Station at the 40,000-sq.-ft. Hangar 1 facility.

Because of the unique nature of the project, the project scope involved challenging architectural, civil/structural, electrical, and mechanical engineering designs. The construction activities included the demolition and construction of a new 40,000-sq.-ft. flooring system with an in-trench drainage system.

In 1994, NAVFAC and NAVAIR embarked on a project to reevaluate fire protection criteria for high-bay aircraft hangars. It was determined that a new fire protection system that didn't damage multi-million-dollar aircraft if it was inadvertently activated was necessary. "The development of the new low level foam nozzle is the latest among numerous changes that stemmed from that research," said Jones. As a result of the Navy's efforts, NFPA 409 Standard for Aircraft Hangars was significantly revised. These revisions reflect the culmination of five years' worth of research, development and testing by the government and private sector.

For more information, contact Joshua Jones P.E., fire protection engineer, NAVFAC-Southwest Division, (619) 532-2058,, or Michael Reynoso, ARUSI director of general contracting, (602) 431-2175,