STANDARD LUBRICATING OIL SvSTfiM FOR GfiARED TURBINES. 267 



aljout 200 gallons per minute. If the circulation of oil had been 100 gallons per minute 

 instead of 200 gallons, the temperature drop would have been 24 degrees, or just double. 



It was mentioned in connection with the size of the cooler that additional area should 

 be provided to take care of certain deposits, etc., in the tubes. I have not found any diffi- 

 culty from these deposits, and it would seem to me, in case there were deposits in the tubes, 

 the thing to do would be to clean them with kerosene or some other cleansing agent. 



The necessity for suction strainers is rather questionable, and they have since been 

 omitted from this order. The size of the mesh in the discharge is given as l/64th of an 

 inch, to remove the sediment. It is not believed that all sediment can be removed by the 

 use of strainers; certain fine particles will go through and can only be removed by settling 

 and filtering. It seems to me that openings anywhere from 1/32 to 1/64 of an inch are 

 satisfactory. 



On page 246 the subject of filters and separators is treated, and under that subject it is 

 noted that the gravity supply tanks are arranged for settling the oil. It is not considered 

 good practice to do this, and it is believed to be better practice to provide a separate tank 

 for settling the oil, so that all the dirt and sludge deposited will, as far as practicable, be 

 kept out of the circulating system. 



The alarm systems which were provided for in this order have not given very satisfac- 

 tory results, and it is believed that it would be better to eliminate the electrical features and 

 provide some purely mechanical method of giving an alarm in case the oil pressure fails. 



On page 247 mention is made of the oil pumps becoming vapor bound. This condition 

 in the pumps may be due to several things — ^of course, hot oil contributes to it — but the 

 condition is aggravated by high velocity and friction in the suction pipe and by high piston 

 speed in the pump. Lubricating oil pumps should be conservatively rated, and our practice 

 is to put in pumps about one-third the catalogue rated capacity. 



In regard to the viscosity of the oil, originally the >lubricating oil was specified to have 

 a viscosity of 700 seconds at 100 degrees — that is a very heavy oil, which gives rise to cer- 

 tain complications. In the first place, the oil requires very large coolers to extract the heat 

 on accoimt of its viscosity. In the second place, if the engineers allow the oil to^ get too 

 cool, it becomes very sticky and does not flow properly in the pipes, and in one case I know 

 of a serious accident occurred due to the oil not flowing through the gears and bearings. 

 It would seem that an oil of medium viscosity — one coming between 300 and 500 seconds — 

 is more suitable for geared turbine units. 



On page 248 it is mentioned that the first cost of installing this system is quite high. 

 We found it quite high, about double the cost of the pressure system which we put on pre- 

 vious vessels. 



There are a number of details and other points in the paper which may be questioned. 

 Most of them are minor details and really matters that the designer should be allowed lati- 

 tude in handling. In general, this system is considered unnecessarily complicated for cargo 

 steamers, and does not seem to comply closely enough with practical requirements. 



Mr. W. L. R. Emmet^ Member of Council: — I would ask Mr. Fernald to advise what 

 the approximate cost of such a system is. 



Mr. Fernald: — It may be put in for about $21,000. We had estimated running to 

 twice that amount. 



The President : — Is there any further comment ? 



