This paper deals with transients following the rapid opening of a valve on the upstream sides of fluid lines containing air pocket or liquid column. Experiments using test pipelines were carried out for the parameter variations in various elements. A theoretical calculation was first performed by applying Runge-Kutta-Gill-methods for the basic equations of lumped-element representation, and then, the pressure surge due to collision of a liquid column was calculated. The principal points obtained are summarized as follows: (1) There is a possibility that the pressure surge for an open system with small orifice-pipe cross sectional area ratio AR is greater than that of a confined system. (2) Effects such as those of AR, mass of liquid column and gradient of a pipeline on pressure surge were clarified. (3) Methods for the approximate calculation of the pressure surge are effective for predicting the transients of fluid lines containing air pocket or liquid column.