الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
A correct determination of the internal pressures in closed conduits is an important factor in their design. in ordinary pipes with a straight alinement the computation o-f internal pressures is rather simple. It is limited to determination of the height of the piezometric line above the center line of the pipe after which a multiplication of this piezorneter height by the unit weight of water gives the average value of the internal pressure within the pipe. This pressure is normally called “Positive” that is, in regard to the pressures exterted by air,it is greater than the latter and their difference is positive. However, there are cases in which pressure become “negative” or smaller than the pressure exterted by air. Such cases occur (a) in closed conduits when the vertical alinement is above the piezometric line, (b) in conduits behind valves or gates and (c) in siphons in which the effect of the curvature of the flow filaments is revealed by a distribution of internal pressures different from hydrostatic pressures. In siphons, the prcssures may become either positive or negative. Expressions for the pressure and velocity within a siphon are derived in the scope of this study. The accuracy of these forjpulae have been checked against the corresponding measured values, which produced satisfactor’y agreements.