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16
FUEL AND LUBRICATING OIL SYSTEMS
 
A. FUEL OIL SYSTEM
 
16A1. General description. All fuel oil stowage tanks lie between the inner and outer hulls. There are four normal fuel oil tanks No. 1, frames 35-41; No. 2, frames 41-46; No. 6, frames 93-99; No. 7, frames 99-107. There are six reserve fuel oil tanks: No. 3A, frames 57-62 starboard; No. 3B, frames 57-62 port; No. 4A, frames 69-75 starboard; No. 4B, frames 69-75 port; No. 5A, frames 75-80 starboard; and No. 5B, frames 75-80 port. (See FigureA-7.) These six reserve fuel oil tanks make up the fuel ballast tank group.

Each tank is connected to three piping systems: the fuel oil filling and transfer; the compensating water; and the 225-pound service air system. The 3-inch filling and transfer main, with a main deck filling connection at frame 33 and another at frame 69, has two branches to each fuel oil tank, one for each side of the tank. The 3-inch compensating water main, with a deck hose connection at frame 88 and an outlet through a head box, has a branch to the bottom of each fuel oil tank. (See FigureA-27.)

Between frames 91 and 93, there are two tanks: the expansion tank on the port side and the collecting tank on the starboard side. Located in the conning tower sheers is a head box with a vent and overflow which is kept filled with water from the main engine circulating water system. A 3-inch line carries the water from the head box to the bottom of the expansion tank. Another line is run from the top of the expansion tank to the 3-inch compensating water main. These two lines and all branches off the main are provided with stop valves. Each one of these stop valves, except for the hose connection, is kept locked in the open position. The head of water keeps the tanks completely filled at all times. Thus provision is made for the change in volume caused by the variation in temperature and also for changes in pressure, so that the tank is always equalized with sea pressure when submerging.

  The 3-inch fuel filling and transfer main has a branch to the bottom of the collecting tank, and another line is run from the top of this tank to the engine clean fuel oil tank. Hence, water under pressure from the head box passes through the expansion tank, to the compensating main, and them to the fuel oil tank being used as the supply. From the supply tank, oil flows through the transfer main to the collecting tank and on to the clean fuel oil tank. The stop valve in the collecting tank supply from the 3-inch transfer main is locked open; so locked, valves provide for transfer and compensation under all conditions of operations when a tank, either normal or reserve, is open to the transfer main. A supply tank must always be open to the filling and transfer main, otherwise the collecting tank is subjected to the depth pressure when submerged.

Filling operations are effected through the forward and after deck connections described above. The head of oil forces the water overboard through the deck hose connection for the compensating main or through the expansion tank and head box.

In case of damage to the head box, pressure is kept on the compensating system by a line to the compensating main from the main motor circulating water system in the motor room. Normal operation requires that the stop valve in this line be locked shut. This practice of locking the stop valve during normal operation assures that the compensating system will operate without drawing water from the main motor circulating water system. On the surface, the main engine circulating water system is sufficient to keep the head box full, thus maintaining a constant pressure on the expansion tank and from it to the fuel oil tank on service and the collecting tank. Fuel oil leaving the collecting tank under the compensating system pressure may either go to the purifier and from there by gravity to CFOT, or it stay go to the fuel transfer and purifier pump. The fuel

 
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Drawing of fuel transfer and purifier pump
Figure 16-1. Fuel transfer and purifier pump.
 
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transfer purifier pump discharges fuel oil to the main engines. The pump may therefore serve as a standby for the main engine fuel pump since the fuel transfer purifier pumps can take a suction on the line from the collecting tank to the purifier; the transfer main and the CFOT discharge this oil directly to the main engines. The fuel transfer purifier pumps may also discharge directly overboard. Purifying is not normally done submerged. However, if it is, the depth pressure will maintain a constant pressure on the compensating system.

There are two fuel transfer and purifier pumps: one in the forward engine room, supplying clean fuel oil tank No. 1, and one in the after engine room, supplying clean fuel oil tank No. 2.

The fuel pump is the positive displacement gear type. A d.c. motor of 1 horsepower furnishes the driving power at 1150 rpm operating speed. This pump has a capacity of 10 gallons per minute.

The operating parts include the valve body, the rotor and idler, and the relief valve which is set to open at 45 psi. (See Figure 16-1.)

A bypass line is provided from the transfer main to the fuel transfer and purifier pump for use in the event of bilging the collecting tank. Also, a branch from the head box is run to the compensating main so that the expansion tank may be bypassed. The stop valve in each of these lines is normally locked shut.

The collecting tank is provided with a drain line to the drain pump for the removal of water from the bottom of the tank. The

  drain pump is provided with a discharge to the compensating water main to permit pumping the bilges to the top of the expansion tank, forcing water overboard from the bottom of the tank. This removes the necessity of discharging bilge water directly overboard.

Valves are provided on the branches from the transfer main to the deck filling connections for obtaining samples of the oil. Fuel tanks are provided with a blow and vent manifold, with blow and vent connections to each side of the tank from the manifold. The manifold is provided with gages and relief valves set at 15 psi. When blowing a fuel tank, water must leave the tank through the compensating water main. Balanced hydraulic gages (liquidometers) are installed in the expansion, collecting, and clean fuel oil tanks to indicate the oil content.

The connection from the compensating. water line to the compensating water manifold and to the head box is provided with a sight glass to check the pipe contents when filling, blowing, and pumping operations are being conducted.

The fuel oil tanks and the compensating water line should be vented frequently to prevent formation of air pockets. Filled oil tanks should be vented in the following order expansion tank, fuel oil tank or tanks in use, collecting tank. The discharge from collecting tank to clean fuel oil tank should be shut when venting.

It is essential that all air be excluded from the fuel oil system, as fuel will not readily flow past an air pocket under the small head pressure provided by the head box.

 
B. RESERVE FUEL OIL TANKS
 
16B1. General. Fuel ballast tanks Nos. 3A, 3B, 4A, 4B, 5A, and 5B may be used either as ballast tanks or as reserve fuel oil tanks. When used for reserve fuel oil tanks, the fuel ballast tanks must be isolated from the 600-pound main ballast tank blowing system, and the 10-pound main ballast tank blowing system. All the blow valves leading to these tanks from both the 600-pound and the 10-pound blowing manifolds must be secured,   and the flood valves to these tanks locked shut. This prevents either the compressed air or the sea water from entering the tanks and interfering with the proper operation. of the fuel oil system.

The main and emergency vent valves to the fuel ballast tanks must also be secured.

Each of the fuel ballast tanks is provided with one vent valve. Blank flanges are provided for the valve openings in the reserve

 
165

Drawing of lubricating oil purifier
Figure 16-2. Lubricating oil purifier.
 
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fuel oil tanks and are to be installed when fuel is carried in the tank. These blank flanges are stowed in the superstructure, adjacent to the vent valves, and the gasket used with the blank flange is stowed in the ship.

To attach the blank flange, proceed as follows: Open the vent valve a slight amount to relieve the tension on the spring mechanism. Remove nuts, tap bolts, and distance pieces from studs in the finished face on the outside of the valve openings. Remove the pin through the lower end of the bellcrank

  and connecting link and put the gasket in place over the studs. Attach the blank flanges in place over the studs and replace the nuts and tap bolts and set up to make a tight joint. Put the distance pieces in a bag, label them, and stow in ship. After the blank flanges are in place, return the operating mechanism to the locked shut position.

The emergency vent valves for the reserve fuel oil tanks are provided with padlocks. When fuel is being carried in these tanks, the emergency vents will be locked shut.

 
C. LUBRICATING OIL SYSTEM
 
16C1. General. There are three normal lubricating oil tanks: No. 1 between frames 79-85, No. 2 between frames 90-96, and No. 3 between frames 107-109. One reserve lubricating oil tank is located between frames 76-77 port. There are four main engine sump tanks: No. 1 between frames 80-85 starboard, No. 2 between frames 80-85 port, No. 3 between frames 91-96 starboard, and No. 4 between frames 91-96 port. There are two reduction gear sump tanks: No. 1 between frames 103-105 starboard, and No. 2 between frames 103-105 port.

A filling connection is provided on the main deck between frames 78-79 port; it is connected by a 2-inch line to a four-valve lubricating oil filling and transfer manifold located at frames 78-80 starboard. This manifold is connected directly to each of the normal lubricating oil tanks and reserve lubricating oil tanks.

The tanks are normally filled by passing the oil through a strainer before it reaches the manifold; however, this strainer may be bypassed. The lubricating oil tanks are provided with a blow and vent manifold with blow and vent connections from the manifold to each tank. Air is furnished from the 225-pound service air lines through a reducing valve set for 13 psi and a relief valve set for 15 psi. Oil may be blown from any storage tank to any other tank; also, oil to be discharged may be blown or pumped overboard through the deck filling connection or through a 1 1/2-inch hose connection from the filling line.

  An accessory to the lubricating oil system is the lubricating oil purifying and flushing system. The principal part of this system is the lubricating oil purifier (See Figure 16-2.), used to separate impurities from the lubricating oil. There are two lubricating oil purifiers: one located in the forward engine room amidships and the other in the starboard forward end of the after engine room. The major part of the lubricating oil purifier is a hollow cylindrical rotor called the bowl, the top part of which is connected by a coupling nut to a spindle, which in turn is attached to and suspended from a ball bearing assembly. Three flat plate wings are spaced radially equidistant inside the bowl. This three-plate assembly has a cone on the bottom with which the feed jet comes in contact, thus increasing the liquid flow evenly and eliminating emulsion formation.

The spindle is belt-driven by an electric motor fastened on the back of the frame. The belt tension is maintained by an idler pulley to assure smooth acceleration.

When the pump is running, the liquid is jetted into the bowl and, upon coming in contact with the three flat plates, is rotated at the speed of the bowl. This rapid rotation causes centrifugal force to act on the liquid, thus separating the heavier from the lighter components in the liquid. Solids, sludge, and water (the heavier parts) are forced through the oil layer to the outside where they form a layer on the wall of the bowl.

As the oil in a purified condition reaches the overflow or discharge port, it is carried

 
167

Drawing of fuel oil system
Figure 16-3. Fuel oil system.
to the lubricating oil pump and distributed to the engines.

The lower end of the bowl is set in a guide bushing which shifts in accordance with the position required by the center rotation of the bowl.

The lubricating oil purifying and flushing system may be used to perform the following functions:

1. Flush engines prior to starting.
2. Purify the lubricating oil.
3. Supply engines with lubricating oil.
4. Clarify the lubricating oil.

Clarification of the lubricating oil is accomplished by the Sharples centrifuge

  which also serves as the fuel oil purifier just described. The machine is set up as a clarifier by installing a clarifier sleeve or ring dam on the top of the bowl, thus closing the outlet passage through which the water is discharged. The term clarifier is applied to the machine when it is set up to discharge a single liquid from which solid matter has been removed by centrifugal force. If the machine is set up to separate two liquids from solid matter and from each other (such as oil and water in a fuel oil purifier), it is called a separator. The machine is usually set up as a separator for fuel oil purification and a clarifier for lubricating oil purification.
 
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Version 1.11, 16 July 2010