HYDRAULICS 

 COEFFICIENTS FOR VALVES 



363 



Sudden Change of Section. When the area of a cross-section 

 of a pipe is suddenly enlarged or contracted, in the latter case, 

 by inserting a smaller pipe or by an obstruction, the coefficient 

 of hydraulic resistance is 



(H 



in which A is the area of the larger cross-section, and a that of 

 the smaller one. 



HYDRAULIC TABLES FOR LONG PIPES 



The following table is compiled for pipes whose lengths 

 are more than 1,000 times their diameter. The data given are: 

 (1) the velocity of flow in feet per second; (2) the corresponding 



slope -, that is, the available head per unit length of pipe; and 



(3) the discharges, in cubic feet per second, both for a clean and 

 an extremely foul pipe, thus giving the extreme limits between 

 which the discharge may vary. 



