The leak law: from local to global scale

Due to the experimental evidence, in the last decades the leak law, i.e. the relationship between the system functioning conditions and the leakage, has been seriously questioned. Some corrections have been introduced in the classical orifice equation to take into account all the relevant parameters it depends on (e.g. leak shape, pipe material and thickness, ...). Even if a perfect law is derived for a single leak in a pipe still an open issue remains, that is the use of the same leak law for a whole network or district. In terms of practical applications, the link from a single leak outflow to a system leakage is relevant since it allows the transfer of the results from laboratory experiments to real systems –from the local scale of a single leak to the global scale of a district with several different leaks. In this paper the effect of the spatial variation of the leak law parameters at the local scale on leak law determination at a global scale are considered. Conclusions on the possible comparison between the laws at the two scales are given.