772 



TRUEBLOOD. 



tion of any ordinate lying between the locus of observed points and a 

 line through the origin having a slope equal to the true value of ju, 

 represents, for the pressure drop in question, the heat-leak per unit 

 mass of fluid, occurring during transit through the plug, divided by 

 the specific heat at constant pressure. 



It will be seen from Figs. 15 and 16 that a simple linear equation 

 can express the relation between AT and Ap with fair accuracy in 

 most cases. With the further aid of a relation connecting flow and 

 pressure drop, both of these quantities may be eliminated from equa- 

 tion (2), leaving an equation expressing 5Q as a function of AT" only, 

 provided f^ is known. Such relations are of some value in a compara- 

 tive study of heat leakage in different types of apparatus. 



The relation between flow and pressure drop which has just been 

 mentioned is expressed quite accurately by 



<4) / = K (ApY 



for the present experiments. Here r is approximately ^ for axial flow 

 plugs and approximately | for radial flow plugs. In Fig. 11, logarith- 

 mic plots of flow against pressure drop for several plugs are given. 

 Table II gives the constants of the equation (4). 



2. Discussion of the Experimental Results. 



a. General. 



In the plots of Figs. 11 to 16 inclusive, the designations attached to 

 the several curves have the following significances: 



* The relation (4) is only roughly true for these plugs, owing to choking of 

 the plug while in service. This is very noticeable with radial flow plugs, 

 especially where the steam has not been previously strained through an alun- 

 dum strainer. The same porous cup was used in all radial flow plugs, and the 

 variations in the constants are due to the gradual 'aging' of the cup. The 

 plugs are listed in chronological order. n 



