Gunnery Officer



Information Sheet Number: 1.21



Magazine sprinkler systems are designed to store explosive ordnance and automatically contain and suppress fires. The Gunnery Officer is responsible for ensuring the working order of the designed systems. This is accomplished through effective scheduling of maintenance and supervision of divisional personnel. A good working knowledge of the installed systems is a prerequisite for an accomplished Gunnery Officer.


(a) NAVSEA S9522-AA-HBK-010 Description, Operation and Instruction Book for Magazine Sprinkler Systems

(b) NAVSEA OP 4 Ammunition Afloat

(c) COMNAVSURFLANTINST 9093.3 Combat Systems Officer Manual



1. The detailed specifications for construction of U.S. Navy ships are developed and approved by NAVSEASYSCOM.

a. NAVSEASYSCOM establishes and designates ammunition stowage spaces for various types and classes of ships.

b. They may also consider de-certification of magazines for poor material conditions.

2. The term "magazine" applies to any compartment, space or locker which is used for the stowage of explosives or ammunition of any kind.

3. There are many different types of magazines on ships. They are designated specifically for the type of ammunition they are to contain.

a. Primary magazine

(1) Stowage spaces they are usually located below decks, and if possible, below the water line.

(2) They are provided with an automatic sprinkler system.

(3) Spaces are well insulated and are provided with some type of ventilation system.

b. Ready service magazine

(1) Spaces are located near the weapon or area to be serviced.

(2) They provide permanent stowage for part of the ammunition allowance.

(3) Spaces are normally equipped with insulation, ventilation and sprinkler systems.

c. Ready service lockers

(1) Certain compartments or lockers provide for the stowage of special types of ammunition or ammunition components such as:

(a) Detonators

(b) Pyrotechnics

(c) Chemicals

(d) Grenades

(e) Fuzes

(2) Less security is generally required.

(3) They provide the least favorable protection from the elements.

4. Ventilation

a. Magazine ventilation system shall be operated as necessary to prevent overheating or condensation of moisture.

b. They should be secured with watertight covers closed whenever ventilation is not required to maintain the temperature below 100E F. Closing the covers prevents moisture, condensation, or freezing temperature in a magazine.

c. In hot climates magazines can be maintained at a lower average temperature by closing off the air supply during the heat of the day and running the blowers only at night when cool air can be forced in.


5. Gas check seals

a. In any projectile which has a base plug, base fuse or both, great care must be taken to ensure that these threaded joints are sealed to prevent any leakage of hot gases from the burning propellant from penetrating the explosive cavity of the projectile body.

b. Copper and leads rings known as gas check seals are pressed into special grooves containing the joint to form a gas-tight seal.

c. Improperly installed gas check seals may cause premature in-bore explosions and close-aboard detonations by permitting hot gasses to enter the explosive filler area of the projectiles.

d. Fleet users shall check for damage to gas check seals which may have occurred during handling, transportation, and stowage subsequent to issue by an ammunition activity.


1. The primary purpose of the magazine sprinkling system is to extinguish any fire in the magazine and/or cool the ammunition in the magazine in the event of a fire in an adjacent space. There are two types of sprinkling systems in use:

a. WET TYPE - water is present throughout the system up to the sprinkler heads. It is primarily used for missile magazines. The MK 41 VLS Deluge system is an example of a wet type sprinkling system.

b. DRY TYPE - water is present only up to the control valve. The piping between the control valve and sprinkler heads is dry. The majority of all installed magazine sprinkling systems are of the dry type.


a. OPEN LOOP. The open loop contains all of the valves and piping used to open (actuate) the magazine sprinkling system control valve (magazine sprinkler valve) and flood the magazine.

b. CLOSED LOOP. The closed loop contains all the valves and piping used to close (secure) the magazine sprinkling system control valve after it has been actuated.

c. ACTUATING PRESSURE. Activating pressure is the firemain pressure used to actuate or de-actuate the magazine sprinkling system.



(1) Manufactured by the CLA-VALVE company

(2) Commonly called "CLA Valve"

(3) Comes in all sizes up to eight inches (measured at the seat)

(4) Normally closed globe type valve which must be fully opened to allow firemain water to enter the dry side of the system

(5) Hydraulically operated, three part valve

(a) Main Body is located between the dry piping and the firemain system.

(b) Powertrol Body contains the operating shaft, disc, and diaphragm chamber.

(c) The cover is bolted to the Powertrol body and contains a sight glass on its top.

(1) Sight glass allows an indicator to move up and down as the valve is opened and closed.

(2) Indicator is the only means to monitor operation of the valve during testing.

(3) The cover also contains a heavy spring which is used to keep the valve closed by exerting pressure on the disc which seals the seat of the valve.

b. Test Fitting (Test Casting)

(1) Supplied with each valve for use during PMS checks or whenever the system is worked on

(2) Under NO circumstances should the test casting be left in the valve

(3) When not in use the fitting must be kept in a secure place, normally the ships armory. NOTE: Each magazine sprinkling valve has its own test casting which must have the number of the sprinkling system stenciled on it. Additionally, Gunnery Officers must personally ensure that these items are accounted for through periodic inventories.

(4) Operation

(a) Actuating pressure entering the diaphragm chamber forces the diaphragm to raise against the spring pressure.

(b) The area of the diaphragm and the pressure in the chamber are sufficient to overcome the force of the spring, allowing the disc to raise off the seat in the main body, admitting the salt water from the firemain system into the dry side of the piping and out to the sprinkling heads.


(1) The Manual Control Valve is a three position valve that is positioned manually to activate or deactivate the sprinkling system.

(a) OPEN position provides activating pressure to the magazine sprinkler valve.

(b) CLOSED position provides pressure to deactivate the magazine sprinkler system.

(c) NEUTRAL position is the normal position of the manual control valve.

(2) Normally there are two manual control valves used with any system.

(a) Local station is usually in or near the magazine.

(b) Remote station is usually outside the magazine on the same deck as the magazine or a deck above.

(3) Operation

(a) The normal position of this valve is with the handle in the NEUTRAL position. When in Neutral, firemain pressure is available at the top of the valve for use when needed.

(b) When the valve is shifted to the OPEN position, actuating pressure enters the OPEN LOOP piping and opens the Magazine Sprinkler Valve to flood the magazine.

(c) When the valve is shifted to the CLOSE position, the actuating pressure is allowed to enter the CLOSED LOOP piping, thereby securing the system and stopping the flooding of the magazine.


(1) This is the most commonly used and numerous valve in a magazine sprinkling system.

(2) Five Spring Loaded Check valves are used in a DRY TYPE magazine sprinkling system.

(a) There is one in the OPEN LOOP from the Pneumatically Released Pilot (PRP) valve.

(b) There is one valve in each OPEN LOOP and CLOSED LOOP from the remote and local stations.

(c) As with all check valves, its purpose is to permit the flow of actuating pressure in only one direction while blocking the flow in the other direction.

(3) Operation

(a) We need to pressurize only one OPEN LOOP or CLOSED LOOP at a time; therefore, the valve is placed to prevent the pressurization of unneeded piping.

(b) The use of check valves allows the use of common piping for different functions and gives the system a faster reaction time.


(1) The REMOTE CONTROL VALVE is a normally open valve which is the connecting point between the OPEN and the CLOSED LOOP of the magazine sprinkler system.

(2) The valve is of two piece construction.

(a) The main body is in the OPEN LOOP of the system piping.

(b) The top of the valve contains a diaphragm and disc which are used to close the valve whenever the CLOSED LOOP is pressurized.

(3) The normal position of this valve is OPEN with OPEN LOOP actuating pressure free to pass through the valve whenever pressure is applied to the Open Loop.

(4) The top of the valve contains a connection to the CLOSED LOOP.

(5) The use of this valve in the system allows the sprinkling system to be secured whenever the system has been actuated in automatically or from a station other than the one which actuated the system.


(1) Hydraulically Operated Check Valve is a NORMALLY CLOSED check valve.

(2) It is a hydraulically operated, three part check valve similar in construction and operation to the Magazine Sprinkler Control valve.

(a) MAIN BODY is located in the OPEN LOOP and prevents pressure from passing through the valve.

(b) POWERTROL BODY is mounted above the main body and contains a diaphragm and shaft which opens the valve.

(c) COVER is bolted to the Powertrol body.

(3) When OPEN LOOP actuating pressure is applied to the input side of the valve, the OPEN LOOP pressure is blocked.

(a) This is due to the normally closed condition of the valve.

(b) The output side of the valve is connected to a drain line.

(4) When CLOSED LOOP actuating pressure enters the diaphragm chamber the diaphragm is forced to raise against the spring pressure, opening the hydraulically operated check valve.

(a) OPEN LOOP pressure, previously stopped by the closed condition of the valve, is now allowed to pass through the valve and out through a drain line.

(b) CLOSED LOOP pressure, at the same time, closes the remote control valve thus stopping any OPEN LOOP pressure from getting to the CLA valve.

(c) Opening the hydraulically operated check valve allows the system to dump the pressure trapped between the remote control valve and the CLA valve.

(5) The spring in the CLA valve closes the valve and the magazine sprinkler system is secured.


(1) Two orifice plates are used with the DRY TYPE system.

(a) Plates are made of 1/8 inch flat plate monel.

(b) Each plate has a 0.098 inch hole drilled through the center.

(c) There is one orifice plate for each loop in the sprinkler system.

(2) The purpose of the orifice plate is to prevent any buildup of pressure in either the OPEN LOOP or CLOSED LOOP due to a leak past the PRP or manual control valve.

(3) If there is a leak in the OPEN LOOP side of either the manual control valve or the PRP Valve, there will be a flow of water observed at the opening of the drain line.

(a) With the valves in the OPEN LOOP secured, no water should be observed from the drain line.

(b) Any indication of leakage should be checked immediately.

(4) If there is a leak in the CLOSED LOOP side of either manual control valve, there will be a flow of water observed at the opening of drain line #2.

(a) With the valves in the CLOSED LOOP secured, no water should be observed from drain line #2 (orifice plate #2).

(b) Any indication of leakage should be checked immediately.



(1) The PRP valve operates on the principle of a pressure differential. The valve uses air vice firemain pressure, as an actuating agent.

(a) It receives actuating input from Heat Sensitive Devices (HSDs).

(b) HSDs are connected to the PRP at a six port manifold located on the top of the PRP Valve.

(c) Maximum of two HSDs, connected through check valves, can be attached to each port. This allows a maximum of twelve HSDs to be attached to each PRP Valve.

(2) The PRP valve uses a diaphragm made from thin sheet brass.

(a) One side of the diaphragm is connected through a manifold to the HSDs which are mounted on the overhead in the magazine.

(b) The other side of the diaphragm is connected to an actuating plunger.

(c) The PRP valves have very sensitive internal parts and should never be opened for repair or calibration.

(3) When the pressure on the rear (HSD) side of the diaphragm becomes greater than the front (plunger) side, the diaphragm is pushed forward.

(a) When the diaphragm is pushed forward, it pushes the actuating plunger into the trip mechanism, opening the pilot valve.

(b) When opened, the pilot valve allows actuating pressure to enter the OPEN LOOP of the magazine sprinkler system.

(c) The normal pressure difference required to actuate the PRP valve is about eight ounces.

(4) Securing the magazine sprinkler system after being actuated by the PRP valve, is accomplished with the following steps.

(a) Shift one of the manual control valves to the closed position.

(b) Close the seawater service (lock shield) valve to the PRP.

(c) Shift manual control valve back to the neutral position.

(d) Reset the PRP valve using the appropriate tool and bleed the excess pressure.



(1) The HSD (also called a Thermosylphon Device) is the unit that creates the differential pressure across the diaphragm of the PRP valve.

(2) HSDs are located in the overhead of the magazine.

(a) There is one HSD for each 120 sq. ft. of deck.

(b) HSDs are connected to the PRP Valve by a length of 1/8th inch covered tubing.

(3) The HSD is made up of a bellows, spring clip, fusible link, and a cage.

(a) The bellows and clip are connected together and extend out of the cage.

(b) The spring is inside the cage and compressed by the bellows.

(c) The bellows is held in place by the fusible link.

(4) The HSD has two operating features

(a) Rate of rise - A rapid increase in magazine temperature causes the air in the bellows to expand. The pressure travels to the PRP diaphragm. The valve trips when there is a pressure differential of eight ounces in the PRP valve.

(b) Fixed Temperature - The fixed temperature feature is based on a slow increase in magazine temperature. When the temperature in the magazine reaches 160 degrees, the fusible link will melt, allowing the spring to expand. When the spring expands, it collapses the bellows sending a burst of air down the tubing to the PRP valve. This burst of pressure creates the pressure differential needed to trip PRP valve and flood the magazine.



(1) The PRP valve has a limited number of connections on the manifold for attaching the HSDs. By joining two HSDs together, through the use of a "tee", we can attach more HSDs to the manifold.

(a) Connecting two HSDs together makes it necessary to use a circle seal check valve.

(b) Circle seal check valves are mounted on the bulkhead from 8 to 12 inches above the PRP Valve.

(c) There is one valve for each HSD in the magazine.

(d) The two HSD lines are joined below the circle seal check valves.

(2) Circle seal check valves block the flow of air in one direction and allows air to pass in the opposite direction.

(3) Flow of pressure is down through the valve from the HSD to the PRP valve.

(4) Use of the check valve prevents splitting the actuating pressure.

(5) Splitting of the pressure could be enough to prevent the PRP diaphragm from tripping the PRP valve.



5. Quarterly and monthly PMS is conducted to ensure operation of the sprinkler system. This maintenance must be witnessed by the Combat Systems/Weapons Officer or a designated representative.

6. Magazine Actuation Control

a. Automatic Actuation

(1) Heat Sensing Device (HSD) - senses a fixed temperature and/or a rate of temperature rise, and sets off the sprinkler system.

(2) Pneumatic Release Valve (PRV) - HSD will cause the PRV to open, allowing firemain to supply the sprinkler system.

b. Manual Actuation

(1) Manual control valves are located inside the magazine and adjacent to the access to the space.

(2) Personnel must manually rotate the valve to activate the system.

c. Water Injection System (Missile Magazines Only)

(1) Designed to protect the magazine in case of accidental booster ignition.

(2) Small force will trip nozzle which points directly into the missile booster.

(3) Cools the booster and helps protect remaining missiles.

7. Manual activation of magazine sprinklers requires the permission of the Commanding Officer or, in absence of the CO, the Command Duty Officer.


1. Alarms DO NOT activate magazine sprinkler system. The alarms are merely an indicator of trouble in the magazine. The ONLY way the sprinkling system can be activated is through use of the PRP valve or one of the manual control valves.


2. "F" Circuit

a. Magazine high temperature alarm

(1) Bimetallic switches are activated when the temperature in magazine reaches 105 degrees F.

(2) Each switch is installed in the overhead so that there is one switch for every 250 sq. ft. of deck space.

(3) There is a minimum of two switches per magazine.

2. "FH" Circuit

a. Sprinkler alarm used to indicate the presence of water in the dry side of the piping

(1) Usually located in the dry side of the piping about six or eight inches from the CLA valve.

(2) This alarm contains two contacts mounted in a fiberboard disc.

(a) The disc is located in a low spot of the pipe.

(b) When water enters dry side of piping, either through flooding or leakage, the water drops into the alarm and bridges the contacts.

(c) Because water is an electrical conductor, the alarm will become energized.

3. "FD" Circuit

a. Water alarm used to indicate the presence of a liquid on the deck of the magazine

(1) The alarm consists of a float and two contacts located in the lowest spot in the magazine (about 1/2 inch above the deck.)

(2) Any liquid on the deck (salt water, fresh water, fuel, etc.) will flow to the lowest spot in the magazine.

(a) The liquid will cause the float to lift and bridge the contacts.

(b) Once the contacts are made, the alarm will become energized.

(3) The "FD" circuit is also tied into the "FH" circuit so that both alarms will energize when the "FD" circuit is energized.

4. Indicator stations

a. Alarms usually sound a bell in three places:

(1) Bridge

(2) Quarterdeck

(3) IC Room

b. Bridge and Quarterdeck only reflect that an alarm has sounded.

(1) Check in IC Room to determine what space is indicated by the alarm.

(2) Gunners Mate should investigate immediately.

5. When alarms or sprinkler systems are de-energized, the ship is required to:

(1) Secure the smoking lamp in the area of the magazine.

(2) Provide manned hoses to compensate for designed systems until the problem is rectified.











































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