192 NEW DEVELOPMENTS IN HIGH VACUUM APPARATUS. 



sometimes will go to 30 degrees, in which case a higher vacuum would be obtained. In 

 many cases the operating force on board ship will run the circulating pumps at high speed 

 with a cold sea-water temperature and maintain a vacuum well above 39 inches, when actu- 

 ally they are losing steam by doing so, because the turbines are not able to utilize efficiently 

 that high degree of vacuum. 



The table on page 183, giving a comparison between the twin-beam air pump and two 

 air ejectors and one condensate pump, is substantially what we found in an investigation for 

 our vessels of this subject, and, as will be noted, there is quite a difference in the weight, 

 and in the space also. The weight, the space and the arrangement, of course, are matters 

 of study for each particular installation. In the case of the vessels constructed by the Fed- 

 eral Shipbuilding Company, we found there was a material advantage, taking everything into 

 consideration, for air ejectors, and for that reason we installed air ejectors on all the thirty 

 vessels which we constructed for the Emergency Fleet Corporation, in addition to a num- 

 ber of other vessels which we now have under construction. 



On page 184, the author refers to the use of piston type pumps for the removal of con- 

 densate. I call attention to this because of the idea that a good many people have that only 

 a turbine-driven centrifugal pump can be used for the removal of condensate. We have pre- 

 pared designs for the use of both turbine-driven condensate pumps and piston-driven con- 

 densate pumps. We selected the turbine pump, since to us it appeared to have some advantage 

 — at least for turbine-driven ships, where the men are familiar with that type of machinery. 

 The piston condensate pump, of course, can be either of the vertical or horizontal type, de- 

 pending on the particular arrangement of the installation where it is used. 



The piston speed of the condensate pump as given by Mr. Kothny appears to be a little 

 low. Of course this is somewhat a matter of choice, and naturally it allows for a larger fac- 

 tor of safety in the capacity of the pump. 



On page 185, the author refers to a re-circulating pipe, with a strainer, thermostatically 

 operated, etc. It is not necessary to provide automatic circulation of the water for prevent- 

 ing high temperatures in a feed tank. This can easily be handled by hand, and, in the later 

 vessels which we have built, we have eliminated the thermostatic control because we found 

 that it worked quite well enough in this way. The thermostat, however, is a refinement 

 which, if kept in proper order, will undoubtedly add to the luxury of the installation. 



In regard to Mr. Katzenstein's comments on Plate 68, I hardly think these criticisms are 

 constructive. It is evidently very difficult to state what the air leakage into a condensing 

 plant is going to be, since it will vary so much with the design and construction of the in- 

 stallation. Yet the designer must have some leakage to use in the design of his plant. His 

 assumed leakage may not be exactly right, but he must have something that he can use for 

 determining the size of the air pump which is to be used. In fixing the capacity of most 

 pumps, certain standard conditions of construction and installation of the plant are assumed, 

 together with a standard air leakage for this design and type of plant. A pump is then pro- 

 vided which will take care of this air leakage and a great deal more ; that is to say, a factor 

 of safety will be provided for handling this quantity of air. The quantity of air to be han- 

 dled in any given installation is an arbitrary value. It depends on assumed standard condi- 

 tions, and I think that Mr. Kothny's effort to reduce it to some sort of a standard is of value. 

 It is certainly better than no standard at all. As far as I have been able to find out, this is 

 the way it is done in most cases. If the air pump is anywhere near large enough (that is, 

 if it is based on good practice) and if you do' not get the required vacuum, you go around 



