check valves allow air and water to escape from themagazine into one of the ventilation ducts or throughan independent air escape.Exhaust VentsMost magazines, particularly missile magazines,are vented to the atmosphere. When missile motorsburn, they rapidly produce large volumes of smoke andgas. If a missile motor should accidentally ignite in amagazine, the smoke and gas will be vented directly tothe atmosphere, rather than to other areas of the ship.The area on the weather deck in the vicinity of anexhaust vent is potentially hazardous and is marked towarn personnel not to loiter in the area.Magazine AlarmsMagazines are equipped with various alarm andsensing devices. When activated, they provide audibleand visual warnings that something is wrong. An alarmmay mean that an actual problem exists or that aproblem is developing. Designated personnel shouldinvestigate any activated alarm immediately. Thefollowing paragraphs discuss three common alarms.FH ALARM CIRCUIT.—The FH alarm circuitis used with a magazine’s sprinkler system to indicatetwo system problems: leakage and activation. Leakageindicates that a problem is developing. Actuationmeans that water is flowing and the ammunition isgetting sprayed. Actual sprinkling can result from areal fire or a high heat buildup in the magazine. It alsocan result from a gross sprinkler system malfunction.In any case, appropriate action must be takenimmediately.F ALARM CIRCUIT.—The F alarm circuit isalso known as the high-temperature alarm circuit. Itsounds an alarm when magazine space temperaturereaches a dangerous level. If the F alarm sounds, youshould investigate the problem immediately! If youreact quickly enough, you may be able to takemeasures to reduce the temperature. This may preventthe sprinkler system from activating.COMBUSTIONGASANDSMOKEDETECTOR.—Some magazines may contain acombustion gas and smoke detector. This detector isanother early warning device similar to a smokedetector in a house. It detects the presence ofcombustion gases and smoke particles in the air formedin all types of fires and in smoldering or overheatedmaterials. These particles are so small that they areinvisible to the human eye; however, they are presentbefore there is any evidence of flame.MAGAZINE INSPECTIONSAboard ship, magazine inspections are mandatoryand are an integral part of the ship’s PMS. Theseinspections must be conducted by qualified personnelusing a check sheet (maintenance requirement card) toensure that a hazard or abnormal condition is notoverlooked.It is not within the scope of this manual to discussin detail the criteria of all required magazineinspections. However, we can provide a briefdescription of daily magazine inspectionrequirements.Daily Visual InspectionsThe daily visual inspection of magazines generallyconsists of checking for improperly secured stowage,unsatisfactory protective packaging, unusual fumes orodors, magazine cleanliness, and any other abnormalcondition.Abnormal conditions in a ship’s magazine orammunition stowage space include evidence oftampering to gain access (broken, damaged, or missinglocks), evidence of theft, and the presence ofunauthorized materials. Abnormal conditions alsoinclude evidence of localized overheating fromadjacent compartments on decks, bulkheads, andoverheads; indications of leaks from sprinkler or floodpipes, nozzles, or control valves and regulators; andinoperable or damaged reachrods, linkages, automaticfire alarm devices, and other similar equipment.Another important requirement of the dailyinspection is to observe, record, and report maximumand minimum temperature conditions.Magazine TemperaturesTemperature is the most important factor thataffects powder and propellant stability. This is why it’simportant to monitor temperature conditions.Temperature readings are normally taken once aday. The exact time may vary, but most ships take thereadings in the morning (around 0800 for example),using a special maximum and minimum thermometer(sometimes called a high-low thermometer). Figure5-5 illustrates a typical maximum and minimumthermometer.5-13
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