■170 THE APPLICATION OF SMALL STEAM TURBINES 



might say that figures which I have show interesting comparisons between the turbine-driven 

 centrifugal boiler feed-pump and the direct-acting types, these of equal capacity. They show 

 that, when correctly proportioned, the direct-acting pump is not only more economical but is 

 financially the better investment. When the capacity grows excessive, however, the advan- 

 tage of the centrifugal type becomes apparent. Two hundred and fifty thousand pounds of 

 feed water per hour is as large a capacity as has been required in one unit for shipboard use 

 at the present time, so far as I know, and this for reasons of fuel economy, due to the 

 necessity of dividing the total feed water capacity between two or three units. I make these 

 statements of these two types of pumps not in criticism of the steam turbine-driven set, as 

 it has its proper place, but protest against the indiscriminate use of turbine-driven boiler 

 feed-pumps where they have no place. Some steamship owners can testify to the poor 

 results obtained by putting turbine-driven boiler feed-pumps in places where they do not 

 belong. 



The statement concerning the tests at Annapolis, referred to in the sentence at top 

 of page 169, is not correct, in that the test of the simplex pump was conducted under 

 circumstances that were decidedly unfavorable. Therefore a comparison between the per- 

 formance of that pump and the turbine-driven pump is hardly correct. If comparisons are 

 made between these two types they should be based on the performance of the centrifugal 

 pump referred to, as compared with the tests at Annapolis on a 24-inch stroke Blake recip- 

 rocating pump. This Blake pump gave results in economy better than any of a similar type 

 before or since tested, and showed that, despite the claim for better water rate per brake 

 horse-power, the overall duty was in favor of the reciprocating machine. 



The water hammer in piping from direct-acting pumps can be eliminated if the piping 

 and pumps are properly proportioned. 



I notice the authors refer in the paper only to turbine-driven feed pumps on U. S. naval 

 vessels. I might add that the Oceanic Steamship Company vessels Sierra, Sonoma, Ven- 

 tura, etc., as well as the Matson Navigation Company steamers and vessels of the Union Oil 

 Company, are fitted with such pumps, those first mentioned above having been installed some 

 years prior to their adoption by the Navy Department. 



Mr. London and Mr. Herbert (Communicated) : — Mr. Francis B. Smith refers to 

 several accidents that have taken place due to bursting of turbine shell or cylinder, but we 

 are glad to note that the accidents mentioned were almost entirely, if not entirely, attributed to 

 the manner of installation and not in any way due to the design or type of machine employed. 

 It is fair to assume that had reciprocating engines been employed under similar circum- 

 stances the result would have been equally if not more serious. 



Mr. Martin L. Katzenstein raised some interesting points in connection with the compar- 

 ative performances of centrifugal versus reciprocating pumps. Mr. Katzenstein takes excep- 

 tion to our statement that "within reasonable limits the efficiency of the turbine matters little." 

 * * * But we think that he contradicts himself later on by stating that the efficiency of 

 such turbines alone is not of prime importance except as an engineering development. We 

 tried to show in our diagram. Plates 79 and 80, that a big variation in water rate was per- 

 missible without materially affecting the overall efficiency. Then assuming that in some 

 cases the reciprocating pump shows up a little better, the difference is hardly worth taking 

 into account, especially when considered in conjunction with the many advantages of the 

 centrifugal type as outlined in the paper. 



