MAGAZINE SPRINKLER SYSTEMS

Sprinkler systems are used for emergency cooling of, and fire fighting in, magazines, ready-service rooms, ammunition and missile handling areas. A magazine sprinkler system consists of a network of pipes. These pipes are secured to the overhead and connected by a sprinkler system control valve to the ship's firemain system. The pipes are fitted with spray heads or sprinkler-head valves. They are arranged so that the water forced through them showers all parts of the magazine or ammunition and missile handling areas. A modern sprinkler system can wet down all exposed bulkheads at the rate of 2 gallons per minute per square foot. It can sprinkle the deck area at the rate of 4 gallons per minute per square foot. Magazine sprinkler systems can completely flood their designated spaces within an hour. To prevent unnecessary flooding of adjacent areas, all compartments equipped with sprinkler systems are watertight. Upper deck handling and ready-service rooms are equipped with drains that limit the water level to a few inches.

The two basic types of hydraulically controlled sprinkler systems are the firemain-operated dry type and the firemain-operated wet type. Both types may be found on the same ship. However, the dry type is normally installed in gun ammunition magazines and the wet type in missile magazines. The Gunner's Mates maintain these sprinkler systems. However, you will need to consider what effect you will have on the sprinkler systems when you conduct planned maintenance on, or make repairs to, the firemain system.

FOG AND WATER CURTAINS

Nonautomatic fog heads are installed at specific boundary bulkheads on certain decks of ships such as transports and cargo ships. They put out transverse fog curtains to prevent the rapid _{spread of fires.} These installations make it possible to sectionalize a ship for fire protection with a series of fog curtains.

Water curtains are installed on aircraft carriers that are not equipped with a hangar foam sprinkler system. The water curtains are used to sectionalize the hangar to provide fire protection. The water curtains have shovel-type open sprinkler heads and are installed athwarthship.

FIXED FOG-SPRAY INSTALLATIONS

In naval ships that have bulk stowage of gasoline, the hazard warrants the use of fixed fog-spray installations. These installations are not automatically operated. A fried fog-spray installation consists of fixed overhead piping equipped with fog heads that are connected to two female hose connections. One of these connections is located on the opposite side of a boundary bulkhead of a protected area. The other is located on the deck above the protected area. Use a check valve in the piping area near each connection and a regular hose connection to furnish water to the system. To operate the system, connect a 2 1/2-inch hose to a fireplug and to one of the female connections. Water is then provided to the system.

DRY-CHEMICAL EXTINGUISHERS

Portable dry-chemical extinguishers (fig. 5-40) are used primarily on class B fires. The dry

Figure 5-40.-Dry-chemical extinguisher.

chemical interrupts the chemical reaction that is fire and thereby slows down combustion. PKP is most often used in these extinguishers. This dry chemical is also safe and effective for use on class C fires; however, carbon dioxide (discussed later in this chapter) is preferred, because PKP will foul electrical and electronic components. Also, PKP should not be used on internal fires of gas turbines or jet engines unless absolutely necessary, because of its tendency to foul engines.

The most common size of PKP extinguisher is the 18-pound size. These extinguishers also come in a 9-pound and a 27-pound size. Most of the PKP extinguishers have a small CO2 cartridge mounted on the outside of the extinguisher shell. This cartridge provides the propellant charge for the extinguisher. Do NOT pressurize the PKP extinguisher until you are ready to use it.

The procedure for operating a dry-chemical extinguisher is as follows:

1. Carry the extinguisher to the scene of the fire.

2. Pull the locking pin from the puncture lever marked PUSH.

3. Push the puncture lever down to cut the seal of the CO2 cartridge. The extinguisher is now ready to use.

4. Approach the fire from the windward side, if possible. Hold the extinguisher in one hand and the nozzle in the other hand.

5. Discharge the dry chemical by squeezing the squeeze grip on the nozzle. Hold the nozzle firmly and direct the dry chemical at the base of the fire. Use a wide sweeping motion from side to side. This will apply a dense, wide cloud of dry chemical in the area. Remember that the extinguisher has a reach of approximately 20 feet.

6. Be certain that all of the fire in the area in which you are working is extinguished before you move in farther. If the fire appears to be too large or if there is a possibility of being outflanked or surrounded by flames, attack the fire with the assistance of two or more personnel using extinguishers.

7. Do not try to economize on the dry chemical. Use as much as necessary (and as many extinguishers as necessary) to completely extinguish the fire.

8. Always back up dry chemical with water or foam.

After a dry-chemical extinguisher has been used, invert the cylinder, squeeze the discharge lever of the nozzle, and tap the nozzle on the

deck. This will release any pressure left in the cylinder and cartridge and any dry chemical left in the hose and nozzle. By inverting the cylinder, you prevent further discharge of dry chemical and conserve the powder. Make sure that dry chemical does not remain in the hose and nozzle; it will cake up and clog them.

To recharge a dry-chemical extinguisher, proceed as follows:

1. Invert the extinguisher and tap the side of the cylinder with the nozzle to knock down any loose dry chemical. Then bleed off the pressure.

2. Remove the fill cap. Do NOT lean over the top of the extinguisher when removing the fill cap.

3. Fill the cylinder with dry chemical only to the bend in the tube. The extra space allows the powder to be aerated when the cylinder is pressurized. This ensures that the powder will not be caked when it is applied.

4. Remove any dry chemical from the internal threads of the bottle and from the threads of the cap.

5. Replace the fill cap.

To install a new CO2 cartridge, proceed as follows:

1. Lift the lever cutter assembly and insert the locking pin.

2. If the extinguisher is to be restowed in the rack, pass a lead wire seal through the locking pin and around the cutter lever.

3. Unscrew the expended CO2 cartridge.

4. Remove the cap and gasket from a new CO2 cartridge.

5. Screw the new cartridge, which has lefthand threads, into the female fitting of the cutter assembly.