SPRINKLER AND ALARM SYSTEMS

Primary and missile magazines, ammunition handling rooms, and most ready-service magazines are fitted with sprinkler systems. Sprinkler systems consist of spray heads or sprinkler-head valves arranged to dash water directly on the munitions and completely cover the magazine's interior. Sprinkler systems for spaces located below the damage control deck (second deck on aircraft carriers) are arranged for local control at the valve and for remote control from the damage control deck (fig. 11-6) On aircraft carriers, the remote controls are normally divided into two groups-forward

Figure 11-6.-Typical magazine remote and local operating sprinkler stations,

sprinkler control board and aft sprinkler control board. The forward magazine group and the aft magazine group sprinklers can be remotely activated from the two control boards. Sprinkler systems for spaces located on and above the damage control deck are arranged for local control only from a position outside the access entrance to the space.

NOTE: Some magazines are designed without sprinkler systems so water-activated ammunition can be stowed in them. For example, Mk 58 marine location markers cannot be stowed in magazines that can be flooded. Also, weather-deck lockers and 20-mm and 40-mm ready-service rooms do not require sprinkler systems.

Sprinkler Systems

Sprinkler systems are classified by the type or location of the control exercised over the valves that restrain the flow of water. These valves maybe operated manually (fig. 11-7) or by remote control (manually or automatically). There are three types of remote operation

1. Manual, by operating gears

2. Hydraulic, by means of control cocks and water from the fire system or control cocks and oil pressure supplied by hand pumps

3. Automatic, by means of a rate of rise or combined rate of rise and fixed temperature thermopneumatic control system

The rate of rise is indicated in a magazine when the temperature increases rapidly (such as from a fire). The rapid temperature increase activates the sprinkler-alarm device (FH circuit), which, in turn, automatically activates the sprinkler system control valve.

Alarm Systems

There are three alarms that are commonly associated with all magazine sprinkler systems-a sprinkling (FH circuit) alarm, a flooding (FD circuit) alarm, and a high-temperature (F circuit) alarm.

High-temperature alarm systems (F circuit) are installed in all of the following magazines or spaces:

Ammunition and propellant stowage areas

Ammunition handling spaces

Ammunition assembly/disassembly/check-out areas

Cargo ammunition holds to provide a means of determining high temperatures

Don't confuse the F circuit with the FH circuit. The F circuit detects a slow rise in temperature while the FH circuit detects a rapid rise in temperature.

Install a minimum of two thermostats in each space. Install a minimum of one thermostat for each 250 square feet of deck area, or fraction of a deck area. If high temperatures occur in any of the spaces containing

Figure 11-7.-Typical manual control sprinkler system. 11-14

thermostats, the high-temperature occurrence is indicated on an alarm switchboard installed in an area continuously manned when the ship is underway. Usually, this is damage control central. Audible alarm systems are also installed in the pilot house, officer-of-the-deck (OOD) area, secondary damage control station, and each interior communications room. The audible alarm systems work in conjunction with the F and FH circuits.

Tests and maintenance of the magazine sprinkler systems are performed periodically according to NAVSEA and applicable preventive maintenance system (PMS) instructions.