Protective Air Vessels for Rising Pipe Lines

Abstract

A long rising pipe line should be protected against the damage due to shock (or “water hammer”) which might ensue if the pumps suddenly failed. The most satisfactory method is to fit an air vessel on the delivery side of the pumps. The connexion between the air vessel and the pipe line should be constricted so that the oscillations of the water-level in the air vessel are damped. An approximate method is described in the paper for calculating the maximum expansion and pressure of the air, and its predictions are shown to be in satisfactory accord with experiment. The onset of water hammer, observed when damping was carried too far, was found to occur at velocities somewhat greater than theory suggests.