Military Base Suppresses Fire Automatically

Military Base Suppresses Fire Automatically

FEATURES

FIRE PROTECTION

With 33 buildings protected by supervised fire and smoke detectors, sprinkler systems, and an automatic high caliber AFFF delivery system, South Dakota's Air National Guard base is a front runner in automatic fire protection for military bases.

If all goes according to plan, by next year the South Dakota Air National Guard (SDANG) will have a new fire detection, alarm, and suppression system protecting its equipment, buildings, and A-7 fighter-bombers. The system, estimated to cost $610,000, has already been designed by the engineering firm of DeWild Grant Reckert and Associates Company of Sioux Falls, SD. When completed, the system will be dispersed throughout the 33 buildings at the base, which is located at Joe Foss Field in Sioux Falls, SD.

The most important component of the entire system will be located in the base’s fuel maintenance dock and hangar, a 19,000 square-foot building that also contains storage space and the avionics shop. Because this structure can hold several A-7 aircrafts, worth nearly $7 million each, it is vital to provide fire protection to this area.

The hangar, which is the largest portion of the building, will have 24 ultraviolet sensors to detect fire. They will be located about 8-10 feet above the hangar floor.

Also around the hangar, about 3 feet off the floor, will be six nozzle turrets designed to spray aqueous film-forming foam (AFFF) across the floor. These nozzles will be stored in an upright position and will operate at 100 psi. They will automatically oscillate to flood the area under the wings of the aircraft, an area usually unreachable by ceiling-mounted fire suppression systems.

To pressurize the AFFF dispensing system, a 150-horsepower fire pump will force water into a bladder tank containing the foam. There is enough foam to spray the hangar floor for 10 minutes. By the end of that time the foam will be four to five feet deep, and the airport fire department should be on the scene.

After the foam supply is exhausted, water will continue to spray from the nozzles, which are located three to a side on the hangar. (The front and back of the hangar are sliding doors to accommodate the movement of the aircraft.) Because of the water requirements of the AFFF system, a new water supply line to the hangar had to be designed specifically for the fire suppression system.

If any ultraviolet sensor in the hangar detects initiation of flame, an alarm will be sent to two consoles: one at the Base Security Office, the other at the airport fire station. Simultaneously, sirens, warning lights, and the AFFF system’s fire pump will be activated. However, if the signal from the first ultraviolet sensor is not followed by a signal from another sensor or a manual switch within five minutes, the AFFF system’s pump will disengage, and the alarms will stop ringing. This is a safeguard against false alarms, which could be caused by the flash of a welding torch.

If more than one ultraviolet sensor finds a flame, the alarms on the consoles and the sirens around the base will change their tones to alert base personnel that a fire condition exists. At the same time, a 30-second time delay will begin, and the AFFF system’s six nozzles will swing down from their storage positions. If, within those 30 seconds, someone does not abort the procedure by hitting a dead-man switch—of which one cannot let go until the entire system is deactivated from a master control panel—the nozzles will begin dispensing the AFFF.

The problems associated with extinguishing inaccessible fires under planes and in other hidden areas in hangars is solved by the horizontal delivery of large amounts of AFFF through automatic high pressure nozzles.

The AFFF system is not entirely automatic. The foam dispensing nozzles can be operated manually. If a manual switch is thrown, the system will go into operation immediately.

The base’s avionics section, located in another part of the building, will be equipped with a fusible-link water sprinkler system. Even though this area houses much high-voltage electrical equipment, water will be used to control fire here. Military experience shows that water is more effective than chemicals for fighting fires in such areas.

In order for this operation to be activated, a fusible link in the sprinkler system must melt, a detector set off, or a manual switch thrown. When the sprinklers are turned on, the electrical current to the heavy equipment in the room is automatically cut off.

The remainder of the buildings on the base will have more standard fire detectors and alarms. In each building, the detectors will be hard-wired to that structure’s fire alarm panel. From there a coded signal will be sent by radio to the two master control panels on the base and at the airport fire station. In addition to indicating the fires and their locations, these systems will also report any faults that may be present in the circuits.

Another feature of the system is that air-handling units are automatically shut off once a fire alarm is sounded. This prevents additional air from being fed to the flames.

Presently, the base is protected by the airport fire station, which is located close to the large hangar. It is operated by the City of Sioux Falls and the SDANG. (The city provides the manpower and the Air National Guard supplies the equipment.)

The station has two P-4 crash vehicles, a P-10 rescue truck, a P-13 quick-response vehicle, and a 1,500-gallon water distributor. The city employs a six-person crew for 24-hour shifts. SDANG supplements some positions with its own personnel, consisting mostly of technicians from the ground crews of the aircraft.

According to one official at the base, the new fire detection, alarm, and suppression systems will catapult the facility to the forefront of fire protection systems among this nation’s military bases.

Four Firefighters Hurt in Fire in Abandoned Harlem (NY) Building

Four firefighters were injured battling a massive fire that tore through an abandoned Harlem building where jazz icon Billie Holiday reportedly once lived.