STANDARD LUBRICATING OIL SYSTEM FOR GEARED TURBINES. 255 



the use of a relief valve that water pressure at cooler inlet should always be less 

 than the outlet pressure of oil from the cooler. As this requirement depends on the 

 arrangement adopted and may necessitate a low setting relief valve on circulating 

 water inlet, with consequent possibility of continuous overflowing to bilges, a spring 

 loaded valve must be placed on oil discharge line from cooler, thus enabling the oil 

 pressure to be artificially raised by adjusting this valve. 



6. The pump shall be of the following specifications: — 



Size 7J/2 by 7 by 10 duplex; pump of other dimensions but with equivalent 

 capacity may be used. Pump shall be designed to operate from the auxiliary steam 

 line at reduced pressure, but the steam ends must be tested hydrostatically for full 

 boiler pressure. 



Pump shall have : — Brass valves, bronze plunger and pump rods. Cast-iron 

 snap rings in pistons. Tufts or equal packing in plunger. Brass liner in water end 

 of pumps. Metallic packing for steam piston rods. Steam cylinder lagged, and cov- 

 ered with sheet metal neatly fitted. Both suction and discharge connections of the 

 flange type, and the dimension shall conform with the American standard. 



7. Oil cooler water circulating pump shall discharge through cooler overboard. 

 H. Strainers, Filter or Separators. — i. A strainer of the twin type shall be 



located in the pump discharge line adjacent to the pumps, and in such a position as 

 to permit the removal of the strainer baskets by lifting them upward. Care should 

 be taken that strainers are located in such a manner as to prevent the sediment fall- 

 ing back into the strainer upon removal of the baskets, or loss of oil when strainer 

 is cleaned. 



2. Strainers are to be so designed that one side can be cleaned while the other 

 is in operation. The valve stems shall be so interlocked that when one valve is 

 closed the other is open. Two spare baskets must be supplied, also a bucket, and a 

 supply of kerosene for cleaning. Strainer castings shall be pickled and thoroughly 

 cleaned before shipment. Internal surfaces in contact with the oil shall not be 

 painted or otherwise coated. Baskets shall be of copper perforated with holes .020 

 inch in diameter. The ratio of straining area to inlet area shall be at least 6 to i. 

 A plate containing adequate instructions for operation shall be placed on each 

 strainer. 



3. Either a centrifugal separator, or a gravity filter of approved type, must be 

 installed as indicated on Drawing E-i 1000-10 (Plate 108), with connection for oil 

 supply to separator or filter through both gravity tanks and the reserve tank. The 

 other connections required by the instruction sheet accompanying the separator or 

 filter shall also be made. A centrifugal separator will be found especially effective 

 in breaking up an emulsion of water and oil, even in a rough sea. The centrifugal 

 separator can be either electric motor or steam driven. If turbine drive is used the 

 design should provide for operation against 10 pounds back pressure, so that the 

 turbine can exhaust into the heater. The gravity filter, while effective in clean- 

 ing the oil, requires the heating and settling to break up an emulsion. Its efifective- 



