CHAPTER 1

MAGAZINES AND MAGAZINESPRINKLER SYSTEMS

LEARNING OBJECTIVES

Upon completing this chapter, you should be able to do the following:

1. Recall the types and designations of shipboard magazines, and the securitymeasures and inspection criteria associated with shipboard magazines.

2. Describe the purpose and functioning of shipboard magazine sprinkler sys-tems. Identify the primary components of magazine sprinkler systems, in-cluding various control valves, gauges, and alarm systems.

MAGAZINES Primary Magazines

In this chapter we will discuss only shipboardmagazines and their sprinkler system. For informationon shore magazines, refer to Mineman, Volume 3.

A magazine is any compartment, space, or lockerused, or intended to be used, for the stowage ofexplosives or ammunition of any kind. A term alwaysassociated with a magazine is magazine area. Amagazine area includes the magazine itself and anyspaces or passages containing magazine entrancesintended to be used for the handling and passing ofammunition. It also includes areas adjacent toexplosive stowages, including loaded ammunitionlighters, trucks, and railroad cars, where special safetymeasures are required.

Magazines are physically located for ease ofreceiving and issuing explosives, the best obtainableprotection (security), and the most favorable stowageconditions.

MAGAZINE TYPES

There are several types of magazines on ships;among these are primary, ready-service, missile, locker,and chemical. Each type is designed specifically for aparticular type of ammunition. In this TRAMAN, wewill limit our discussion to primary magazines andready-service magazines.

Primary magazines are designed as ammunitionstowage spaces, generally located below the main deckand usually below the waterline. They are adequatelyequipped with insulation, ventilation, and sprinklersystems and are provided with fittings so they may belocked securely. Primary magazines can accommodatea vessel’s complete allowance of ammunition forpeacetime operation.

Ready-Service Magazines

Ready-service magazines are spaces physicallyconvenient to the weapons they serve. They providepermanent stowage for part of the ammunitionallowance. Normally they are equipped with insulation,ventilation, and ammunition sprinkler systems, and aresecured by locking. The combined capacities of theprimary and ready-service magazines are normallysufficient to hold the ship’s allowance for war andemergencies.

Regardless of its type, each magazine is marked bya label plate showing its compartment number and thetype of ammunition it is designed to contain.

MAGAZINE DESIGNATIONS

Magazines are designated according to the type ofexplosive they contain. Recall from above that each

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magazine is usually designed to hold only one type ofexplosive. Based on this assumption, a magazine mayhave any one of the following designations:

Powder magazine

Fixed-ammunition magazine

Small arms magazine

Warhead locker

Projectile magazine or room

Bomb magazine

Missile magazine

Fuze magazine

Detonator locker

Pyrotechnic magazine or locker

While stowing only one type of ammunition in amagazine is desirable, it is not always possible, due tospace limitations. Therefore, in certain situationsprescribed by the operational commander, more thanone type of ammunition can be stowed in a magazine.However, the mix cannot include pyrotechnics thathave been removed from their containers or fuzes anddetonators that are not integral parts of the ammunition.These items must be stowed according to the currentinstructions related to the particular items.

Where mixed stowage of ammunition is necessary,precautions should be taken to make sure the varioustypes of ammunition are segregated within themagazine and that each type is suitably marked forready identification. Ammunition Afloat, NAVSEAOP-4, provides answers to specific questionsconcerning stowage requirements.

MAGAZINE SECURITY

In peacetime, all magazines, explosives lockers,ready-service lockers, and areas such as ammunitionhoists leading into magazine spaces are kept closed andlocked, except when they are opened for inspection,ventilating purposes, testing, or authorized work.These spaces are not entered unnecessarily and areopened only when authorized by the weapons officer.The weapons officer is responsible for making sure thatthe spaces are locked when they are not being used.

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The only thing that may be stored in a magazine isthe material it was designed to hold. A magazine maynot be used to store empty paint cans or grease cans, oilywaste rags, or similar fire hazards. Additionally, theonly personnel allowed to be in a magazine are thosewho have business there.

The commanding officer (CO) is the custodian ofall magazine keys. The CO may, however, designatecertain persons under his or her command to havecustody of duplicate keys. The designated individualwill use the duplicate keys each morning to inspect themagazines and take magazine temperatures.

MAGAZINE INSPECTIONS

Every ship has requirements for periodic (daily,weekly, monthly, bimonthly, quarterly, semiannual, orannual) inspections of its magazines and their contents.These inspections should follow the appropriate 3-MSystems maintenance requirement cards (MRCs) andother source publications such as Ammunition Afloat,NAVSEA OP-4.

A magazine is considered to be in satisfactorycondition if an inspection shows that it meets therequirements listed on applicable MRCs. Dailyinspection requirements usually include checking thegeneral condition and cleanliness of the space. Lessfrequent inspections (monthly, quarterly, and so on)normally require a more detailed check of specificmagazine conditions and equipment. The inspectorshould understand each 3-M inspection requirementcompletely and should follow it to the letter. Doing sonot only ensures a safe ammunition storage area but alsofulfills the requirements of periodic inspections, such asthe explosive safety inspection (ESI). ESI inspectorsuse the same inspection criteria as those listed on yourMRCs.

The most frequently conducted magazineinspection is, obviously, the daily inspection. The mainpurpose of a daily magazine inspection is to check andrecord space temperatures. Temperature is the mostimportant factor that affects powder and propellantstability. Because of the importance of maintainingproper temperatures in magazines, we will spend thenext few pages discussing how and why temperaturesare taken, recorded, and evaluated.

Magazine Temperatures

Temperature readings normally are taken once aday. The exact time may vary, but on most ships thereadings are taken in the morning (around 0800 forexample). A special maximum and minimumthermometer is used. (Sometimes it’s called a high-lowthermometer.) Figure 1-1 illustrates a typical maximumand minimum thermometer.

Every magazine or locker will have at least onesuch direct-reading thermometer, located wheremaximum space temperature variations normally occur.It will be installed so that it is readily accessible fortaking readings and for resetting the index pointers.

Figure 1-1.—Bimetallic maximum and minimum thermometer:

A. Internal components; B. Dial face and pointers.

View A of figure 1-1 shows the internal componentsof the device. The temperature-sensitive element is asingle-helix low-mass coil. The coil fits closely insidethe thermometer stem. The bimetal element is carefullysized and aged for lifetime stability, and is covered witha fluid to assure good heat transfer. The fluid alsopermits maximum speed of response and reducespointer oscillations caused by outside vibrations. Thecase and stem are made from stainless steel for strengthand anticorrosion purposes.

View B of figure 1-1 illustrates the dial face of thethermometer. It is 3 inches in diameter, with a plasticwindow to protect the index pointers. The index resetarm is on the outside of the window and is used to resetthe high-low pointers. Temperature graduations on ourexample are marked off in 20-degree increments. Theapproximate readings on this thermometer are 100°F,high; 78°F, present; and 55°F, low. If you are assignedthe duty of taking magazine temperature readings, youshould record the high, low, and present temperaturesand then reset the high and low pointers in line with thepresent pointer. As temperature rises during the day, thepresent pointer will push the high pointer up the scale.As temperature falls during the night, the presentpointer will reverse direction and push the low pointerdown the scale. As the sun comes up, the presentpointer will move back up the scale. Thus, the inspectorwill see three different temperature readings that reflectthe temperature variations throughout a 24-hour period.

The 45-degree spread between the high and lowpointers in our example is a bit large, but is used forclarity. Check the temperature requirements for themagazine you are inspecting and have the magazine air-conditioning (A/C) or ventilating system turned on ifthe temperature rises into the high zone. The optimumtemperature should be around 70°F. If the A/C system isnot working, artificial cooling (fans, blowers) may haveto be used.

The bimetallic maximum and minimumthermometer in figure 1-1 is becoming the standardthermometer in shipboard magazines. However, youmay come across a different model with only amaximum (high) index pointer and a reset knob. Thistype of thermometer is acceptable. The older liquid-in-glass (tube) mercury high-low thermometer is no longerauthorized for shipboard use. If you see one of themercury units in a magazine, notify your supervisor.

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Records of Magazine Temperature Inspections

Like other maintenance procedures, magazineinspections have records that must be maintained. Themost common written records are the daily magazinetemperature report form and the magazine temperaturerecord (fig. 1-2). 3-M Systems records may also beconsidered as records of magazine inspections.

The magazine temperature record is a card posted ineach magazine. Each day, the inspector enters themaximum and minimum temperatures for the previous24 hours in that magazine, The card is replaced everymonth, and the old one is turned over to the weaponsofficer.

The daily magazine temperature report summarizesthe results of magazine inspections for the whole ship.This form includes not only spaces for entering thehighest and lowest magazine temperatures, but also forreporting the condition of the magazines and theirventilating devices, and (under REMARKS) formiscellaneous, nondaily routine work.

The daily magazine temperatures are transferredfrom the record cards to a magazine log that is apermanent record of all magazine temperatures. A

separate section of the magazine log is usually set asideto record the results of the monthly sprinkler systemtests.

MAGAZINE SPRINKLER SYSTEMS

Sprinkler systems are used for emergency coolingand fire fighting in magazines, ready-service rooms,and ammunition- and missile-handling areas. Amagazine sprinkler system is a network of pipes securedto the overhead and connected by a sprinkler systemcontrol valve to the ship’s continually pressurizedsaltwater firemain. The pipes are fitted with sprinklerhead valves arranged so the water forced through themshowers all parts of the magazine or ammunition- andmissile-handling areas.

A modern sprinkler system can wet down allexposed bulkheads at the rate of 2 gallons per minuteper square foot and can sprinkle the deck area at the rateof 4 gallons per minute per square foot. Magazinesprinkler systems are designed to completely flood theirdesignated spaces within an hour. To preventunnecessary flooding of adjacent areas, allcompartments equipped with sprinkler systems arewatertight. Upper deck-handling and ready-service

Figure 1-2.—A. The magazine temperature record; B. Daily magazine temperature report.

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rooms are equipped with drains that limit the maximumwater level to a few inches. Magazines are completelyenclosed; if flooded, they would be exposed to the fullfiremain pressure. The firemain pressure on most shipsis considerably higher than the pressure magazinebulkheads could withstand; therefore, magazines areequipped with exhaust ventilators located in thebulkhead near the overhead. An exhaust ventilator is apipe with a check valve that permits pressure release(usually to topside). Since the diameter of the pipe islarge enough to allow water to flow out as fast as it flowsin, no excess pressure can build up in the magazinecompartment. On newer ships, magazines are alsoequipped with small, capped drainpipes located in thebulkhead near the deck. The caps may be removed inthe adjacent compartment to drain flooded magazines.

Shipboard magazine sprinkler systems arehydraulically- controlled saltwater/seawater-operatedsystems. There are two basic types of sprinklersystems—the dry-type and the wet-type. In the dry-type system, water is not delivered to the sprinklerheads until the system is activated. In the wet-typesystem, water is continually available at the sprinklerheads and is sprayed in the magazine when heatactivates the sprinkler head. Both types may be foundon some ships. However, the wet-type system is beingdiscontinued. Therefore, we will cover only the drytype. Technical information on both types is containedin Magazine Sprinkler System, NAVSEA S9522-AA-HBK-010.

A dry-type magazine sprinkler system consistsbasically of three subsystems. The first subsystem is theloop of piping and valves that delivers firemain water tothe sprinkler heads. The second subsystem is thehydraulic control system. This system uses firemainwater, through smaller piping, to operate the controlvalves in the first subsystem. The third subsystem is thethermopneumatic system. This system providesautomatic control of the hydraulic control system. Amanual valve is installed in the hydraulic control systemto activate the main sprinkler control valve in case theautomatic system is inoperative or slow to respond. Wediscuss all of these subsystems, along with themagazine sprinkler control valve and the alarm system,below.

As you read about each area of the sprinkler system,you may wish to refer to figure 1-3, which shows howthe system components are related. Pay particular noteto the legend list for the symbols. In addition to theorifices and valves, this figure also identifies the OPENand CLOSE loops of the operating pressure circuit.

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MAGAZINE SPRINKLER CONTROLVALVES

Magazine sprinkler control valves (commonlyreferred to as main valves) are globe-type valves,normally closed but designed to open wide whenactuated, to supply seawater to the sprinkler system.They are diaphragm operated and open at a minimumsystem operating pressure of 40 psi.

The diaphragm-operated control valve (fig. 1-4) isheld closed by the combination of firemain pressureacting against the valve disk and valve spring forceacting against the upper diaphragm washer. When thehydraulic control system is actuated, pressurizedseawater from the firemain enters the diaphragmchamber and pushes (via the diaphragm) against thebottom of the upper diaphragm washer. The bottomsurface area of the upper diaphragm washer is largerthan the surface area of the valve disk. This differencein surface areas allows the water pressure in thediaphragm chamber to create a lifting force greater thanthe closing force created by the spring and pressure onthe valve disk. As a result, the valve disk is lifted andwater is allowed to flow through the valve. When thecontrol system is secured, the operating pressure is bledfrom the diaphragm chamber and the valve is closed bythe force of the valve spring.

The control valve may be actuated eitherautomatically or manually. We will discuss automaticactuating first, followed by manual actuation.

AUTOMATIC (THERMOPNEUMATIC)CONTROL SYSTEM

The automatic control system is designed to actuatethe magazine sprinkler system in response to both arapid rise in temperature (caused by an active fire) andthe reaching of a preset temperature (caused by asmoldering fire). The thermopneumatic elements,which monitor the temperature of the magazine andactivate the sprinkler system, generate a pneumaticsignal in response to thermal action. The pneumaticsignal can be either a sudden increase or decrease in airpressure.

The automatic control system consists of heat-sensing devices (HSDs), transmission lines(Rockbestos®- or Rockhide®-covered copper tubing),circle seal check valves, and a pneumatically releasedpilot (PRP) valve.

Figure 1-3.—Hydraulic (SW) and thermopneumatic control systems for magazine sprinkler valves.

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Figure 1-4.—Diaphragm-operated magazine sprinkler control valve.

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Figure 1-5.—Heat-sensing device (HSD).

Heat-Sensing Device (HSD)

The HSD (fig. 1-5) is a thin-walled, air-filled,spring-loaded bellows designed to create a pressure inresponse to either a rapid or slow rise in temperature.

The spring and bellows are held in thecompressed/expanded positions, respectively, by afusible link that connects the bellows to the HSDhousing. The fusible link is designed to part when thelink temperature reaches 160°F (23°F).

HSDs are mounted on the overhead of the protectedspace and are connected to the manifold of the PRPvalve by individual 1/8-inch transmission lines. Acircle seal check valve is installed in each transmissionline.

If an active fire occurs in the protected space, heatfrom the fire will be transferred to the air within thebellows, causing the air to expand and create a pressure.This pressure will be transmitted to the rear of therelease diaphragm of the PRP valve, thereby creatingthe differential pressure necessary to trip the valve.

If a smoldering fire occurs, the pressure within thebellows will increase too slowly to trip the PRP valve.Therefore, the temperature will continue to increase. Ifit reaches 1 60°F (±3°F), the fusible link in the end of thecollet will part, removing the restraint holding thebellows. The bellows will collapse under the tension ofthe spring and create a pressure impulse that will betransmitted to the rear of the release diaphragm of thePRP valve. This pressure impulse will create thedifferential pressure necessary to trip that valve.

Transmission Lines

The lines that connect the thermopneumaticelements to the PRP are called transmission lines andare Rockbestos®- or Rockhide®-covered seamlesscopper tubing.

Vented Check Valve

The vented check valve (fig. 1-6) is a brass, spring-loaded check valve designed to check against a rapidchange of air pressure in one direction and to open whenair pressure is applied in the other direction. One ventedcheck valve is installed in eachtransmissionline (abovethe PRP, with a maximum of 12 per PRP) from an HSD

Figure 1-6.—Vented check valve.

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with the direction-of-flow arrow pointing toward thePRP. Since the PRP manifold contains only six ports fortransmission tubing connection, systems requiringseven or more HSDs will Tee together vented checkvalves, starting with the seventh check valve. Thecheck valves prevent the rapid increase in air pressurecreated in an individual HSD from pressurizing theentire system. The check valve body contains a ventinstalled in a bypass around the main valve. The ventpermits a slow backflow of air to equalize systempressure in response to normal changes in ambienttemperature.

Pneumatically Released Pilot (PRP) Valve

The PRP valve (fig. 1-7) is a normally closedspring-loaded pilot valve that opens automatically toactuate the magazine sprinkler system in response to apneumatic signal from one or more thermopneumaticelements.

The main components of the PRP valve are theoperating mechanism, the compensating vent, and thepilot valve. The operating mechanism and thecompensating vent are housed in a circular bronze case.The pilot valve is mounted on the front of the case and isinstalled in a 3/8-inch line that connects the firemain tothe sprinkler system hydraulic control system piping.

The PRP valve case is provided with shock mounts andbrackets for fastening to a bulkhead.

The operating mechanism consists of a spring-loaded operating lever operated by a release diaphragmthrough a series of linkages and levers. The rear of therelease diaphragm is connected to the tubing from theHSDs. The front of the release diaphragm is open to theinterior of the PRP valve case. When the PRP valve isset, the operating lever is cocked to hold the valveclosed. A sudden or gradual increase in pressuretransmitted from one or more HSDs will move thediaphragm, releasing the operating lever. As theoperating lever moves, it causes the seat holder to moveaway from the seat, thereby permitting seawater to enterthe hydraulic control system piping and actuate thesprinkler system.

The PRP valve is equipped with a compensatingvent that leaks off the slight increases or decreases ofpressure within the HSDs caused by normaltemperature fluctuations in the protected compartment.This leakoff of slow pressure changes equalizes thepressure on both sides of the release diaphragm andprevents inadvertent tripping of the PRP valve. Thecompensating vent is calibrated at the factory andshould not be adjusted by ship’s force.

Figure 1-7.—Pneumatically released pilot (PRP) valve.

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The rate-of-rise circuit is designed to trip the PRPvalve and actuate the sprinkler system when sufficientheat is absorbed by the HSDs to create a definitepressure within the circuit over a given period of time.This pressure acts against the rear of the releasediaphragm to create the pressure differential necessaryto trip the PRP valve. Adifferential pressure of at least 8ounces per square inch across the release diaphragm isnecessary to trip the PRP valve.

NOTE

The gauge mounted on the front of the PRPvalve indicates the pressure within the entiresystem-not the differential pressure. At timesthe gauge may indicate a positive pressurewithin the system. This is a normal conditioncaused by expansion of air within the systemdue to an increase in ambient temperature. Thepressure indicated on the gauge exists on bothsides of the PRP valve release diaphragm.

HYDRAULIC CONTROL SYSTEM

The hydraulic control system operates the valves inthe dry-type magazine sprinkler system. It usesseawater from the firemain to actuate the magazinesprinkler control valve.

The hydraulic control system (which is betterknown as the operating pressure circuit) consists of thecontrol system piping, a manual control valve, ahydraulically-operated remote-control valve, spring-loaded lift check valves, and a hydraulically-operatedcheck valve (normally used with the diaphragm-operated magazine sprinkler valve) or a power-operatedcheck valve (normally used with the piston-operatedmagazine sprinkler valve).

Operating Pressure Circuit (Control SystemPiping)

The operating pressure circuit is used to open andclose the sprinkler control valves. It connects themanual control valves, the hydraulically-operatedcomponents of the control system, and the magazinesprinkler valve. The operating pressure circuit isdivided into an OPEN loop and a CLOSE loop. TheOPEN loop transmits operating pressure from theOPEN port of the manual control valve(s) to theoperating chamber of the magazine sprinkler valve andthe inlet of the hydraulically-operated check valve viathe hydraulically-operated remote control valve. The

CLOSE loop transmits operating pressure from theCLOSE port of the manual control valve(s) to theoperating pressure connections of the hydraulically-operated remote control valve and the hydraulically-operated check valve.

Manual Control Valve

The manual control valve is a rotary disk plate-typevalve installed to permit rapid hydraulic operation ofthe magazine sprinkler valve. Most systems allowmanual sprinkler activation and securing from either alocal operating station or a remote station. Thisapplication uses the three-way, three-position manualcontrol valve (fig. 1-8). Applications that do notincorporate a remote manual control station or anautomatic control feature use a three-way, two-positionmanual control valve.

A locking device, in the form of a key, is installed inthe control valve handle to prevent accidental operationof the sprinkler system. The locking key is secured tothe handle with a single-strand lead-wire seal andfastened to the valve cover by a safety chain.

Figure 1-8.—Manual control valve.

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Figure 1-9.—Hydraulically-operated remote control valve.

Hydraulically-Operated RemoteControl Valve

The hydraulically-operated remote control valve(fig. 1-9) is a diaphragm-operated, globe-type valve thatis opened by operating pressure acting against theunderside of the disk and closed by operating pressureacting on the top of the diaphragm. The purpose of thisvalve is to permit the magazine sprinkler valve to besecured from an operating station other than the onefrom which it was actuated. Additionally, this valvepermits the magazine sprinkler valve to be secured from

any control station when it has been actuatedautomatically.

Spring-Loaded Lift Check Valve

This valve (fig. 1-10) is a spring-loaded,diaphragm-operated lift check valve that closes tightlyagainst reverse flow and opens wide to permit flow inthe normal direction. Spring-loaded lift check valvespermit the control system to be operated from more thanone control station by preventing backflow through theother stations.

Figure 1-10.—Spring-loaded lift check valve.

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Figure 1-11.—Hydraulically-operated check valve.

Hydraulically-Operated Check Valve

The hydraulically-operated check valve (fig. 1-11)is a normally closed, diaphragm-operated, globe-typecheck valve that is opened by operating pressure in theCLOSE loop acting against the underside of thediaphragm. This valve permits the operating pressure tobe vented from the diaphragm chamber of the magazinesprinkler valve, thereby permitting that valve to closerapidly and completely.

Orifices

Two 0.098-inch orifices are installed in the controlsystem piping to prevent a buildup of pressure in thepiping due to leakage past a control system component.The orifices also vent operating pressure from thecontrol system piping when the manual control valve isreturned to the NEUTRAL position. Orifice No. 1 isinstalled in the OPEN loop upstream from thehydraulically- operated check valve. Orifice No. 2 isinstalled in the CLOSE loop adjacent to the operatingpressure connection of the hydraulically-operatedcheck valve. When the control system is actuated, therewill be a steady flow of water from orifice/drain lineNo. 1 and no flow from orifice/drain line No. 2. Whenthe control system is secured, there will be a steady flowof water from orifice/drain line No. 2 and a diminishingflow from orifice/drain line No. 1. When the manual

control valve is returned to the NEUTRAL position, theoperating pressure is vented from the CLOSE loop viaorifice/drain line No. 2, thereby permitting thehydraulically-operated check valve to close.

MAGAZINE ALARM SYSTEMS

Several types of warning devices or systems areused on board ship. One of them is the alarm systemactivated by the water switch (fig. 1-12) on the dry sideof the sprinkler system main (group) control valves.

Several types of warning devices or systems areused on board ship. One of them is the alarm systemactivated by the water switch (fig. 1-12) on the dry sideof the sprinkler system main (group) control valves.This alarm is designated FH and indicates by sound orlight that the main control valve is open or leaking.This alarm is designated FH and indicates by sound orlight that the main control valve is open or leaking.

Figure 1-12.—FH alarm sensor.

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Another type of alarm is the flooding alarm, designatedFD, that incorporates a float switch located near thedeck. As water accumulates on the deck, the float rises,making a set of contacts and sounding an alarm. If thesprinkler system is actually activated, both alarmsshould sound within seconds of each other.

Another type of alarm system, designated the Falarm, is actuated by heat. This alarm sounds when thetemperature in an ammunition stowage area rises to105°F. The sounding of this alarm allows thetemperature to be reduced before sprinkling becomesnecessary.

SYSTEM TESTING

Each sprinkling system must be tested regularly tobe sure that it operates properly. During the test, allcomponents that should operate during an actual use aretested. This is a major test that, if not conductedproperly, could cause damage to both equipment andcareers. Therefore, if you participate in a sprinklingsystem test, follow the approved testing proceduresexactly. The proper officials (weapons Officer, DCCentral, OOD, etc.) should have been notified, and theappropriate tag out procedures should have beencompleted. We will not discuss the specific procedures,but we do need to briefly discuss the use of the testcasting.

Look back at the magazine sprinkler control valvein figure 1-4. If the system is tested without somehowblocking the flow of water through the valve, firemainwater will flow rapidly into the magazine distributionpiping and will probably damage the stores in themagazine. To allow the valve to be tested withoutwetting the magazine, the manufacturers of the controlvalve developed a special plug, called the test casting.

Figure 1-13.—Test casting installed in a magazine sprinkler

control valve.

The test casting is simply a bypass attachment thatallows system water to flow out of the bottom of thecontrol valve, rather than through its normal exit port.Before the control valve is tested, the bottom cap of thevalve is removed and the test casting is screwed, handtight, into the bottom of the valve seat, as shown infigure 1-13. As long as the test casting is properlyinstalled, no water will flow into the magazine duringthe system test.

If you are assigned to install a test casting, be sure toinstall the correct casting. Your ship will have the samenumber of test castings as it does sprinkler systemcontrol valves because each valve comes from themanufacturer with its own test casting. Test castings arenot interchangeable. When a valve is received on boarda ship, the valve and its test casting are both stampedwith the same, unique number. Be sure the test castingyou install has the same identification number as thevalve you plan to test.

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