FOR AUXILIARY PURPOSES ON BOARD SHIP. 169 



DISCUSSION. 



The President : — This paper on "The Application of Small Steam Turbines for Aux- 

 iliary Purposes on Board Ship" is now open for discussion. 



Mr. Francis B. Smith, Member: — I would just like to make a few remarks about the 

 practical end of the turbine pumping machinery. We have a number of them installed for 

 handling water ballast, and we have found them very successful in regard to the capacity 

 for speeds which can be attained by the machinery, but we had several accidents through the 

 bursting of the turbine chest or cylinder. One of them was quite serious, as the engineer was 

 permanently injured, and there were a good many opinions passed in regard to the cause of 

 the wrecking of the machine. I went there and looked into the matter very carefully, and I 

 was satisfied it was caused almost entirely, if not entirely, by the manner of the installa- 

 tion. They had a very large exhaust pipe so as to have as little back pressure as possible, 

 and that was connected in the same exhaust line with all the other auxiliary machines on the 

 boat. The turbine was set down in the lower engine-room at the lowest point of the exhaust, 

 and the lines leading forward, taking in our windlasses and mooring machines, as well as 

 our dynamos and steering engines and everything of that kind, were all set at a higher 

 point, and naturally drained back that way. The accidents all happened within a short time 

 after the turbine had been put in operation. 



I was fully satisfied, after examining the wreck, that it was caused by the condensation 

 in the exhaust lines being rushed back, where there was so little back pressure, into the tur- 

 bine chamber, for I could see where the buckets had been driven over on the other side and 

 had cut right into the body of the casing, so that I was very well satisfied it was the fault 

 of the installation. Our service, outside of these wrecks, has been excellent with those instal- 

 lations. 



Mr. Martin L. Katzenstein, Member (Commimicated) : — Of the various purposes 

 for the application of steam turbines for auxiliary purposes on shipboard, I would discuss 

 briefly some of the points brought up under the topic of turbine-driven pumps as compared 

 with reciprocating types. 



On pages 158 and 159 the authors refer to certain tests conducted at the Naval Academy 

 to bring out the relative advantages of these types. On page 161 the statement appears that 

 "within reasonable limits the efficiency of the turbine matters little in the overall fuel cost as 

 the heat rejected can be turned to useful work, but in the driven member anything below 

 100 per cent must be considered as a dead loss." This same statement applies to any machine 

 that is wasteful of steam. These statements require a little further explanation. Since the 

 small turbines on shipboard must be used for driving something, their efficiency must nec- 

 essarily be considered in combination with generator, fan, or pump. The efficiency of such 

 turbines alone is not of prime importance, except as an engineering development. All rotary 

 or centrifugal types, by virtue of their design, are inefficient. A low water rate per brake 

 horse-power should not be considered alone. The overall duty in million foot-pounds of 

 work delivered per thousand pounds of dry steam supplied should be the basis of comparison 

 between the steam turbine-driven feed-pump and the direct-acting type. In this connection I 



