TABLE OF CONTENTS Another situation that can lead to a large release of gas or vapour is rupture of a pipeline. Pipelines that may give rise to such a release are principally those carrying either high pressure gas or liquefied gas. In each case, while the determination of the initial emission rate is relatively straightforward, the situation then becomes rather more complex.
Accounts of emission from pipelines containing high pressure gas have been given by R.P. Bell (1978), D.J. Wilson (1979b), Picard and Bishnoi (1988, 1989) and J.R. Chen, Richardson and Saville (1992).
An empirical model for flow from a pipeline rupture has been given by R.P. Bell (1978). This model may be written as
with
where A is the cross-sectional area of the pipeline, d is the diameter of the pipeline, f is the friction factor, l is the length of the pipeline, m o is the initial mass flow from the pipeline, m r is a steady-state, or reference, flow from the pipeline defined by Equation 15.9.2, N is a correction factor, P is the absolute pressure, W o is the initial mass holdup in the pipeline, ? is the density and t 1 and t 2 are time constants. The friction factor f is evidently the Darcy friction factor f D (=8 
).
For the correction factor N, Bell gives the empirical formula
He also states that he used...
