260 STANDARD LUBRICATING OIL SYSTEM FOR GEARED TURBINES. 



would use tanks, etc., approximately half the size of these specified. All proposed 

 designs must, however, be submitted to the Engineering Section for approval. 



2. Twin-screw installation. — The standard system will, in general, apply to 

 twin-screw installations, requiring approximately 175 gallons of oil per minute. The 

 only departure from the standard system will consist in branching the supply piping 

 from gravity tanks to each turbine. The return oil piping from turbine bear- 

 ings and gears may also be led to one drain tank common to both turbines. In 

 twin-screw installations requiring a greater capacity than the standard, each tur- 

 bine should be arranged with its own oiling system, and the two systems should 

 be cross-connected so that either system may be used on both turbines. De- 

 pending on the size of the installation, one spare gravity tank and one spare lubri- 

 cating pump for the complete system may be used instead of two ; but for high 

 power installations it is preferable that each system should be in duplicate. All pro- 

 posed designs, however, must be submitted to the Engineering Section for approval. 



M. Lubricating Oils. — i. Extended experience with various oils has shown the 

 necessity of using a heavy oil to protect the low speed train of double reduction 

 gears against pitting and other deterioration. Heavy oils, however, are not well 

 suited for high speed bearings, particularly where the clearance between bearings 

 and journals is small and will produce high bearing temperature and increase the 

 friction loss. As it is not practicable to use either oils of two different viscosities 

 in the same system, or to install separate systems for the gears and bearings, the 

 only practical compromise is to increase the viscosity as much as possible without 

 heating the pinion and turbine bearing. The viscosity of the .oil at the point of 

 entering the bearings can be controlled over a wide range by regulating the amount 

 of water supplied to the oil coolers. 



2. In the tropics, it may be necessary to use both coolers to keep the tempera- 

 ture down, and in northern waters, in the winter, it may be necessary to throttle 

 the water supply to the coolers or cut it out entirely. 



3. The general rule is to keep the oil as cool as possible without overheating 

 the high-speed pinion bearings, paying also special attention to the bearing and thrust 

 at the forward end of turbines. 



4. The temperature may arise to and operate at 160° F. without danger, with a 

 good supply of oil and careful watching. 



5. It cannot be too clearly emphasized how necessary it is to keep the oil pure 

 and clear of water, by using the test cocks provided to denote its presence, by con- 

 sistently heating and settling oil when the presence of water has been detected, and 

 by keeping the oil pressure at coolers at all times above water pressure. Every op- 

 portunity should be taken to remove all sediment from the oil both by heating and 

 settling,'and strainer baskets should always be kept clean and filter cloths regularly 

 renewed. If this is systematically carried out, the oil should last and remain per- 

 fectly lubricant indefinitely and make-up oil be reduced to minimum. 



6. By agreement with the Division of Operations, the following revised list 

 of approved oils has been adopted for use on all installations :— 



